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We present an electrical analysis method for a gamma-ray imaging system based on a resistive network readout. Currently, the array numbers of scintillators and detectors in imaging systems are being increased to enhance the spatial resolution, and resistive network-based readout circuits are used to reduce the number of channels. However, a positioning process is required to identify the channel in which the signal has been generated, which causes positional distortion. For position correction, the positioning characteristics must be measured according to the readout circuit conditions. However, due to the scintillator’s radiation, measurement in a single channel is difficult. In this work, a current pulse is modeled to analyze the positional characteristics of different channels. A current pulse generator and an automatic channel-selection circuit are designed to input signals selectively to each channel. When the input signal duration is 1 $\mu \text{s}$ , the maximum amount of charge generated by the current pulse generator is approximately 1000 pC. Position errors of up to 88.47% are generated, depending on the gain of the preamplifier. Our proposed method can be used for the linearity analysis of preamplifiers and image position correction algorithms.

Radio-over-fiber (RoF)-based front haul architecture has attracted considerable attention for fifth-generation (5G) cellular systems because of its cost effectiveness, however, it is susceptible to harmonic frequency distortion and intermodulation products (IMs) arising from the nonlinearity of the laser diode. To overcome this limitation, an asymmetric electrical predistortion method, using a single Schottky diode with nonlinear characteristics similar to those of a laser diode, was previously proposed. However, its asymmetric structure causes a phase mismatch, which limits the system bandwidth. In this study, we propose an enhanced electrical predistortion technique using dual-parallel Schottky diode blocks. The proposed technique was validated by experiments involving an IM3 drop of approximately 27 dB, and by using identical dual Schottky diode blocks, the phase mismatch in the previously proposed method is completely eliminated. Thus, the applicable bandwidth is extended to 1.8 GHz. This technique can be used to improve the linearity and increase the bandwidth of RoF systems. Additionally, the simple structure is attractive for low-power applications.

In this article, we proposed a resonance characteristic prediction algorithm (RCPA) for calculating resonance characteristics using intensities at discrete points of wavelength. Given fundamental information of the resonator, such as free spectral range (FSR) and full-width half maximum (FWHM), the RCPA can be easily applied to reduce the cost and size of the measurement system for an optical resonator sensor. For example, with intensities at two wavelength points, the whole wavelength characteristics of the resonator can be generated from the derived fitting equation. To verify the RCPA, we designed and fabricated a Fabry–Perot interferometer (FPI) using $300~\mu \text{m}$ of SU-8 2100 as a cavity medium and 100 nm of Cr thin film on a glass substrate. The fabricated FPI had an FSR of 2.35 nm and an FWHM of 1.59 nm. We observed that the wavelength characteristics of the FPI (1535–1537.5 nm) shifted by 0.33 nm/°C when the temperature changed from 25.3 °C to 27.1 °C in steps of 0.2 °C. With an optimized wavelength spacing of 0.31 nm adopted for this article, we confirmed that the resonance characteristic generated from the RCPA followed the same tendency with an average error of 6 pm and a maximum error of 14 pm, as compared with the full spectrum result from the optical spectrum analyzer. We also analyzed the errors due to the changing point number and point spacing. Based on the experimental results, we verified that the resonance characteristic can be measured successfully using at least two intensities at different wavelengths.

A homography method to correct position errors generated in the Compton imaging system using a resistive network is presented. The Compton imaging system is composed of a scatterer and an absorber ...

PurposeThis study explores the effects of interdisciplinary education on engineering students by observing students' competencies before and after the programme.Design/methodology/approachThe effects of interdisciplinary education were studied over three years through the use of a survey to test the social competencies of organisational life and the interdisciplinary competencies of college students. A total of 5,185 responses were collected from engineering students who took part in interdisciplinary education programmes. The survey was conducted during weeks 3 and 14 of each semester, and a comparison test was used to reveal any changes.FindingsAmong the 12 competencies developed or adapted, leadership significantly improved during all six semesters. Analytical thinking, interpersonal competency, professional attitude, global-mindedness, and creative attitudes also improved in some of the semesters.Research limitations/implicationsIt was not possible to control for the effect of classes that students were attending in addition to the targeted interdisciplinary class. However, this study was able to examine empirically the improvement of competencies for future engineers, and its findings provide a basis for future researchers to elaborate on other competencies as well.Originality/valueThe study recommends competencies needed by engineers working in the Fourth Industrial Revolution, examining the effects of interdisciplinary education on competency development. It contributes to strengthening the current trend in universities that seek to reform interdisciplinary education by empirically verifying its effectiveness.

The inherent tradeoff between the optical mode confinement and the propagation loss due to the high dissipation level of metals has proved to be a significant setback in the design of plasmonic waveguide-based devices. In this Letter, we demonstrate a ring-less nanogap resonator consisting of two straight waveguides with metallic layers and a nanogap between. A finite-difference time-domain simulation of the proposed structure reveals that it exhibits a band-stop and lasing characteristics. The obtained full-width at half-maximum, free spectral range, and Q-factor values are found to be improved as compared to those obtained without a nanogap. Thus, to the best of our knowledge, the new resonator and laser structure can be obtained through the waveguide structure without the ring-shaped resonator.

Non-contact printing methods have recently attracted attention in the field of optoelectronics manufacturing including solar cells, light-emitting diodes, photodetectors, and transparent electrodes. Non-contact printing is a powerful and cost-effective technique for high-precision processing through the direct printing of optoelectronic devices. Multimode optical waveguides which are generally fabricated by lithography or reactive ion etching reported exhibiting minimum losses of 0.02 dB/cm and 0.2 dB/cm, respectively. Although these techniques are well established in the fabrication process, it is complicated and possible only with large-scale equipment. Non-contact printing technique can be used to solve these problems. In this paper, we design and demonstrate the printing of optical waveguides with a flexible substrate. The waveguide width was advanced through the nozzle design within 500 μm and applied to the high voltage and nozzle structure so that the capillary force does not damage the pattern.

Detectors such as photomultiplier tubes (PMT) and Si photomultipliers (SiPM) in array are used in the gamma-ray detection system. They convert the light to electrical signal in the form of a current pulse by photoelectric effect. Because size and power consumption of the detection system is determined by the number of output channels in the detector, a resistive network such as a discretized positioning circuit (DPC) has been used for reducing the number of output channels. The current pulse generated in the detector is distributed to four output ports according to a ratio by resistance of the DPC. Then, the distributed current pulses convert voltage pulses by a charge sensitive amplifier (CSA). The detected positions are estimated by the peak value of the four CSA outputs. However, the position errors occur due to the impedance difference between output of the DPC and input of the CSA. In this paper, we calculated input impedance of the CSA according to variation of CSA's feedback component. Also, we analyzed the cause of position error generated by the impedance difference.

Anodic aluminum oxide (AAO) layers with nano-sized pores have been used as shadow masks for the fabrication of two-dimensional (2D) metal nanodot arrays (NDAs). However, the localized surface plasmon resonance (LSPR) of size-controlled NDAs fabricated using AAO masks has not been much studied. In this study, we report on the improved preparation method and utilization of an ultrathin AAO mask for the fabrication of 2D plasmonic metal NDAs. The greatest challenge in preparing an AAO mask is to control the pore diameter and to make it reproducible. AAO masks with size-controlled pores were reproducibly prepared using a two-step chemical wet etching method. Ag NDAs with different dot diameters (42, 60, and 80 nm) and Ag, Cu, and Au NDAs with dot a diameter of 80 ± 5 nm were fabricated on indium tin oxide glass substrates using AAO masks. The wavelengths corresponding to LSPR of 2D metal NDAs were investigated using ultraviolet–visible spectroscopy. Our results show that AAO masks with tunable pores can be used as shadow masks for the fabrication of 2D plasmonic NDAs.

Unlike for noble metals, localized surface plasmon resonance (LSPR) of metallic nanodot array (NDA), which forms a surface oxide layer, has not been fully explored. We have investigated the surface oxide layers, LSPR, and surface-enhanced Raman scattering (SERS) of Au and Ti/TiO2 NDAs with similar shapes. Au NDA and Ti/TiO2 NDA with 80 ± 5 nm diameters were fabricated on indium tin oxide glass substrates using anodic aluminum oxide masks. The native oxide surface layer of Au NDA was very thin, whereas the Ti/TiO2 NDA’s surface was identified as TiO2 due to its inherent oxide layer. XPS depth profiling confirmed that the Ti metal’s surface transformed into a native oxide layer of TiO2 on Ti metal. The SERS signal of the Au NDA was approximately 104 times higher than that of the Ti/TiO2 NDA. The Au NDA’s LSPR had a strong peak centered at 659 nm, while the Ti/TiO2 NDA’s LSPR had a broad peak centered at ~420 nm. The Ti/TiO2 NDA’s LSPR was weak because the native surface layer dampened the LSPR but was clearly observed in the visible light region. These results suggested that Ti/TiO2 NDA has the potential for use as a visible light-responsive photocatalyst in solar energy systems.

A two-dimensional (2D) Ni nanodot array (NDA), made of transition metals with partially filled d-bands, was fabricated on an indium tin oxide (ITO) substrate with good transparency using a porous anodic aluminum oxide mask. A Ni film with the thickness of 50 nm exhibits a broad dip at 437 nm in the extinction spectrum, while a Ni NDA with the diameter of 45 nm shows a broad localized surface plasmon resonance (LSPR) peak at 400 nm. Both the broad-shaped dip and peak are due to the surface plasmon resonance and the d-band related absorption. We confirmed that the size dependence of transition metals is weak in the LSPR spectra of Ni NDAs, with diameters of 45 nm and 90 nm.

A discretized positioning circuit (DPC) based on a resistive network has been developed to reduce the size of a gamma-ray detection system using multi-anode photomultiplier tubes (MA-PMT) in an array, because it can drastically decrease the number of output channels. The output signal from the gamma-ray detection system is a current pulse generated in each tube that contains information about the gamma-ray energy and detecting position in the array. The output current pulse is distributed to four outputs according to the resistance ratio of the resistive network in the DPC, and the detected position is estimated using the height values of the four distributed current pulses. However, owing to parasitic capacitors of MA-PMT connected in parallel to resistors in the resistive network, the four output pulses are affected by the RC time constants. In particular, when the duration of the input signal is not long enough, the height values of the distributed pulses are reduced, and thereby the position error increases significantly. In this paper, we present a new distortion correction method that considers the pulse duration and the RC time constant. In order to correct the position error, we employed homography, which is a coordinate transformation method. The ideal grid was mapped to a new grid for the distorted position. Using this method, error correction was completely achieved, even for short current pulses.

In this paper, a multi-mode waveguide-based optical resonator is proposed for an integrated optical refractive index sensor. Conventional optical resonators have been studied for single-mode waveguide-based resonators to enhance the performance, but mass production is limited owing to the high fabrication costs of nano-scale structures. To overcome this problem, we designed an S-bend resonator based on a micro-scale multi-mode waveguide. In general, multi-mode waveguides cannot be utilized as optical resonators, because of a performance degradation resulting from modal dispersion and an output transmission with multi-peaks. Therefore, we exploited the mode discrimination phenomenon using the bending loss, and the resulting S-bend resonator yielded an output transmission without multi-peaks. This phenomenon is utilized to remove higher-order modes efficiently using the difference in the effective refractive index between the higher-order and fundamental modes. As a result, the resonator achieved a Q-factor and sensitivity of 2.3 &times, 103 and 52 nm/RIU, respectively, using the variational finite-difference time-domain method. These results show that the multi-mode waveguide-based S-bend resonator with a wide line width can be utilized as a refractive index sensor.

We analyzed regular polygonal ring resonators based on multi-mode waveguide using finite-difference time-domain simulation. It consists of the regular polygonal ring waveguide, total internal reflection mirror, and MMI coupler. In general, multi-mode waveguide-based resonator is difficult to use as sensors because of poor output characteristics. By using the low reflectance of the higher-order mode compared to the fundamental mode in the TIR mirror, we designed a regular polygonal ring resonator that can be used as sensors even when a multi-mode waveguide is used instead of a single-mode waveguide. In fabrication, the multi-mode waveguide has a wider line width than the single-mode waveguide, which reduces the process cost and enables mass production. The width and height of the multi-mode waveguide are designed to be 2.5 μm and 2 μm, respectively using SU-8 polymer. The regular hexagon ring resonator shows the highest Q-factor of 1.03×104 among the various regular polygonal ring resonators.

In this paper, we designed hexagonal ring resonator using localized surface plasmon resonance (LSPR) phenomenon to enhance the sensitivity which is a significant factor in bio-chemical sensors. We used a hexagonal ring resonator structure to eliminate the bending loss which is one of the prime factors affects sensitivity. The sensing area of the hexagonal ring resonator with LSPR is deposited metal nanoparticle on cladding which makes difference with general sensing region of the hexagonal ring resonator. In this sensing region, the wavelength of light should be longer than the size of the nanoparticle because the metal nanoparticle reacts the light in specific condition. The sensitivity of the resonator can be improved with using this phenomenon. We used finite difference time domain (FDTD) methods for theoretical analysis. Also, we optimized the structure to reduce LSPR loss and enhance the sensitivity by adjusting type, size, thickness of the metal nanoparticle. As a simulation result, we verified that sensitivity of hexagonal ring resonator with LSPR can be 2.5 times higher than without LSPR.

Localized surface plasmon resonance (LSPR) of Ti nanodot arrays (NDA) has not been studied much due to the surface oxide layer. In this study, we report the LSPR of titania on titanium (TOT) NDA fabricated on an indium tin oxide (ITO) glass using an anodic aluminum oxide layer with through-holes as a shadow mask. After depositing a 50 nm thick Ti layer, the TOT NDA was revealed on the ITO glass by dissolving the mask. The surface of TOT NDA was identified as TiO2 due to surface oxidation. Using XPS depth profiling, a chemical shift from the surface to interior showed a change of 4.6 eV, which corresponded to the difference in the binding energy between the TiO2 and Ti metal at the Ti 2p core level. Thus, the TOT NDA indicated that the Ti metal core was covered with a TiO2 layer. The LSPR of the TOT NDA with an 80 nm diameter was clearly observed at ~420 nm in the visible range, demonstrating the potential application of TOT NDA as a visible light-responsive photocatalyst.

This study is intended to prepare an revitalization plan of region where rural development project is completed through an analysis of the actual condition of facility operation and maintenance in the region where the project is completed. The results of survey of actual condition of facility operation in the region where rural development project was completed showed that the facilities were not self-sufficient in terms of operation and maintenance cost. Therefore, a prerequisite to the revitalization of region where the project is completed is to prepare an alternative plan for increasing the efficiency and applicability of currently already prepared facilities. Second, a project operation organization system should be streamlined and the competency of operation personnel should continue to be strengthened. Third, it is necessary to prepare a support system and establish cooperation networks for increasing the extensibility of project and continuing to induce community revitalization in the region where the project is completed in the future.

The Fourth Industrial Revolution become a major global topic around, and as a result, universities in Korea have been carrying out structural reforms in preparation of a highly technological future. Engineering colleges, particularly, are participating in the reform by supporting interdisciplinary education programs that combine knowledge and experience across a variety of areas. This study attempts to examine the effects of interdisciplinary education for engineering students by observing students’ competencies before and after the program. We studied the effects of education over three years, finding improvements in competencies due to interdisciplinary education every year. Among the 12 competencies we developed, leadership significantly improved during all five semesters. Analytical thinking, interpersonal competency: professional attitude, global mindedness, and creative attitudes also improved across numerous semesters. Future studies can elaborate on competencies based on our findings. Further research is needed on the development of interdisciplinary courses and teaching methods aiming to improve competencies.

Localized plasmonic structures with the periodic ZnO nano-patterns are demonstrated to increase the sensing characteristics of plasmonic sensor. The ZnO nano-patterns with 30 and 50 nm thicknesses are formed on the Au thin film of 50 nm, which have the periodic nano-patterns of 300 nm. Localized plasmonic structures are optimized using the three-dimensional finite-difference time-domain method as a function of incident angle for the width and thickness of the ZnO nano-structures. Localized plasmonic structures with the periodic ZnO nano-holes are fabricated using the double exposure technique by laser interference lithography. The measured resonance angles of 47.5° and 54° are obtained in the localized plasmonic structures with the periodic ZnO nano-patterns of 30 and 50 nm thicknesses, respectively.

We propose a rectangular resonator sensor structure with butterfly MMI coupler using SOI. It consists of the rectangular resonator, total internal reflection (TIR) mirror, and the butterfly MMI coupler. The rectangular resonator is expected to be used as bio and chemical sensors because of the advantages of using MMI coupler and the absence of bending loss unlike ring resonators. The butterfly MMI coupler can miniaturize the device compared to conventional MMI by using a linear butterfly shape instead of a square in the MMI part. The width, height, and slab height of the rib type waveguide are designed to be 1.5 μm, 1.5 μm, and 0.9 μm, respectively. This structure is designed as a single mode. When designing a TIR mirror, we considered the Goos-Hanchen shift and critical angle. We designed 3:1 MMI coupler because rectangular resonator has no bending loss. The width of MMI is designed to be 4.5 μm and we optimize the length of the butterfly MMI coupler using finite-difference time-domain (FDTD) method for higher Q-factor. It has the equal performance with conventional MMI even though the length is reduced by 1/3. As a result of the simulation, Qfactor of rectangular resonator can be obtained as 7381.

A double layered plasmonic device based on transferring technique with polystyrene nano-beads is analyzed and demonstrated to increase the sensing characteristics of plasmonic sensor system. The double layered plasmonic devices are calculated using the three-dimensional finite-difference time-domain method for the width and thickness of the nano-hole structures. The double layered plasmonic devices with different diameters of the Au nano-hole are fabricated by transferring method with commercially available chloromethyl latex with a diameter of 0.42 μm. The optimum sensing characteristic of the proposed plasmonic device is obtained with the film and the hole thickness of 15 and 15 nm in the 246 nm wide nano-hole size. The best sensitivity of the proposed plasmonic sensor is 67.7 degree/RIU when the sensitivity of the conventional plasmonic sensor is 42.2 degree/RIU.

In this paper, we propose temperature sensing method by using optical beating. When temperature changes, a peak wavelength of the sensing laser varies slightly. However, with limitation of the optical spectrum analyzer’s (OSA) spectral resolution (sub-nm), it is hard to measure the exact quantity of the wavelength variation. Therefore, we used electrical spectrum analyzer (ESA) and two lasers to obtain the wavelength shift. We used DFB-LD (distributed feedback laser diode) and TLS (tunable laser source) to get beating signal. Each of laser has 1550 nm of wavelength, -20 dBm of intensity and 108 of Q factor. We varied temperature by 0.1 °C from 17.4 °C to 18.4 °C using TEC (temperature controller). We observed 0.01 nm/°C of wavelength change through OSA and 9.5 GHz/°C of beating frequency change through ESA. With this result, we verified that we can measure relative temperature change with having ultra-fine resolution of 9.5×10-7 °C theoretically for the ESA resolution bandwidth of 1 kHz. This detecting ability can be applied to highly sensitive temperature sensor.

A simple low-current consumption analog predistortion circuit is designed to enhance linearity. The circuit is experimentally verified in a radio-over-fiber (RoF) systems. A Schottky diode is used to compensate for the nonlinearity of RoF systems. An $L$ – $I$ curve for a laser diode is compared with the $I$ – $V$ curve of the Schottky diode and the nonlinear characteristics are analyzed. The predistortion circuit is composed of two paths: 1) the nonlinear circuit with a Schottky diode to compensate for the laser diode nonlinearity and 2) the electrical delay line for a time delay. These two paths are recombined to suppress the IMD3 (third order intermodulation distortion) of the laser diode. Experimental results show that enhancements of $\sim 26$ dBc in the IMD3 and $\sim 7.5$ dB in the spurious-free dynamic range are achieved at 2.4 GHz. The proposed predistortion system has a significant reduction in current consumption compared with previous linearization techniques. In addition, error vector magnitude is satisfied under 4% with 64-quadratic-amplitude modulation.

Satrec Initiative and ATSB have been developing a medium-sized aperture camera (MAC) for an earth observation payload on a small satellite. Developed as a push-broom type high-resolution camera, the camera has one panchromatic and four multispectral channels. The panchromatic channel has 2.5m, and multispectral channels have 5m of ground sampling distances at a nominal altitude of 685km. The 300mm-aperture Cassegrain telescope contains two aspheric mirrors and two spherical correction lenses. With a philosophy of building a simple and cost-effective camera, the mirrors incorporate no light-weighting, and the linear CCDs are mounted on a single PCB with no beam splitters. MAC is the main payload of RazakSAT to be launched in 2005. RazakSAT is a 180kg satellite including MAC, designed to provide high-resolution imagery of 20km swath width on a near equatorial orbit (NEqO). The mission objective is to demonstrate the capability of a high-resolution remote sensing satellite system on a near equatorial orbit. This paper describes the overview of the MAC and RarakSAT programmes, and presents the current development status of MAC focusing on key optical aspects of Qualification Model.

Funded by the Ministry of Commerce, Industry, and Energy of Korea, SI initiated the development of the prototype model of TMA-based electro-optical system as part of the national space research and development program. Its optical aperture diameter is 120 mm, the effective focal length is 462 mm, and its full field-of-view is 5.08 degrees. The dimension is of about 600 mm × 400 mm × 400 mm and the weight is less than 15 kg. To demonstrate its performance, hyper-spectral imaging based on linear spectral filter is selected for the application of the prototype. The spectral resolution will be less than 10 nm and the number of channels will be more than 40 in visible and nearinfrared region. In this paper, the progress made so far on the prototype development will be presented

In this study, a half-circled cavity based microdisk laser diode is proposed and demonstrated experimentally for an integrated photonic biochemical sensor. Conventional microdisk sensors have limitations in optical coupling and reproducibility. In order to overcome these drawbacks, we design a novel half-circled micro disk laser (HC-MDL) which is easy to manufacture and has optical output directionality. The Q-factor of the fabricated HC-MDL was measured as 7.72 × 106 using the self-heterodyne method and the side mode suppression ratio was measured as 23 dB. Moreover, gas sensing experiments were performed using the HC-MDL sensor. A wavelength shift response of 14.21 pm was obtained for 100 ppb dimethyl methylphosphonate (DMMP) gas and that of 14.70 pm was obtained for 1 ppm ethanol gas. These results indicate the possibility of highly sensitive gas detection at ppb levels using HC-MDL. This attractive feature of the HC-MDL sensor is believed to be very useful for a wide variety of optical biochemical sensor applications.

We demonstrated the ion-sensitive field-effect transistors (IS-FETs) based on nanowires (NWs) with different diameters and doping concentrations to obtain the high sensitivity and various applications. The growth of the catalyst-free InAs NWs was carried out using a horizontal reactor MOCVD system (AIXTRON Inc.). A p-type Si (111) wafer (ρ = 1 -10 Ω-cm) was prepared for the NW growth. Here, NWs with diameters of around 50 ~ 150 nm were grown and the doping concentration also was changed around x±1016~18 /cm2. IS-FETs with the grown InAs NWs were fabricated using the photolithography and the lift-off process. The gas sensing characteristics have been investigated through studying the gate response of the NW conductance in different ambient conditions.

In this paper, total internal reflection (TIR) mirror is carefully simulated for silicon nitride polygonal ring resonator sensor structure. Polygonal resonator has recently attracted much attention for applications in bio and chemical sensors because it does not have a bending loss, and it has an advantage of using MMI coupler. In polygonal resonator sensor design, high Q-factor and low TIR mirror loss are extremely significant factors. Therefore, critical angle and Goos-Hanchen shift should be considered in the design of TIR mirror. When cladding material is SiO2, the critical angle of SiNx waveguide is about 44.99 degrees and the Goos-Hanchen shift is about 400 nm at 1.55 μm wavelength. For the rib type waveguide, we designed it to have 3 μm width, 1 μm height, and 0.5 μm etching depth for decreasing TIR mirror loss. As simulation results of FDTD, reflectivitities of polygonal TIR mirrors are 79% for pentagon, 95% for hexagon and 98% for octagon, respectively. According to the simulations, Q-factors for hexagonal and octagonal resonators can be obtained as high as 1.55 x 104 and 1.72 x 104, respectively.

We demonstrated group velocity delay using a metal–insulator–metal structure for slow light that would be very simple to fabricate. A negative Goos–Hanchen shift of the surface plasmon resonance can be caused by incident radiation while reflecting, resulting in a general group delay. Using this phenomenon, we induced a group delay of 70 fs using a very simple 20-μm-long waveguide.

In this letter, a triangular resonator-based surface plasmon resonance (SPR) sensor that uses total internal reflection (TIR) mirrors to provide SPR excitation for the detection of refractive index (RI) change is proposed and first demonstrated using SoI substrate without any gain medium. The fabricated triangular resonator sensor with a 35-nm-thick Au film on a TIR mirror shows an output power increment of 1.2 dB and a sensitivity of 102 nm/RIU, while that nonmetallic layer on a TIR mirror shows 30 nm/RIU. The sensitivity enhancement is attributed to a phase change in the SPR resulting in a large shift of the resonance peak. This configuration provides significant advantages by increasing the sensitivity of the RI sensor even with the extremely small sensing area of the SPR mirror.

We have investigated the electric-field intensity distributions and characteristics of the whispering-gallery mode (WGM) from a planar microdisk using a three-dimensional finite-difference time-domain method. Silicon nitride (Si 3 N 4 ) planar microdisks on silica (SiO 2 ) substrates have been systematically analyzed considering the effects of the sidewall angle, etching depth, and height. Superpositioning of the TE and TM modes which is caused by the skew effect according to the sidewall angle has been demonstrated. Furthermore, the mode splitting caused by the change from single mode to multi-mode regimes due to an increase in the height has been analyzed. Several planar microdisks of Si 3 N 4 on SiO 2 were fabricated, and their resonance characteristics were probed by using micro-photoluminescence spectroscopy. A quality factor of 5×10 3 for microdisks with a diameter of 3.5 μm and sidewall angle of 35° was observed in the visible range. The WGMs of fabricated microdisk were analyzed according to the details of the model and found to be in good agreement

Dept. of Food and Resource Economics(Insti. of Agri. & Life Sci.), Gyeongsang National UniversityABSTRACT : The purposes of this research are to review the current economic measures to be used to assess the economic effects of agricultural infrastructure projects, to find some effects not included into the current measures, and to suggest new additional economic measures. So thus, economic assessment for agricultural infrastructure projects has been criticized to be overestimated. For example, some research reported that the projects enhanced rice productivity by 20% or 30%. We suggest four new measures to evaluate economic effects of agricultural infrastructure projects: (1) enhancement in productivity, (2) switchover from low-income crops to high-income crops, (3) rises in land price, and (4) lower fluctuation in production.Key words : Economic Evaluation, Economic Measures, Agricultural Infrastructure Projects

Rural villages have many problems such as the collapse of rural village communities with continued over-depopulation and aging, reduced functions of towns and villages, deteriorated services with changes in the structure of settlement class and decreased use of the facilities. they also have difficulties in maintenance in spite of the increase of the roles of rural village community facilities. Various plans for the utilization of community facilities to promote the vitality of rural villages and the revitalization of communities have been needed. Thus, this study aimed to offer basic data to seek for future plans to utilize community facilities and reconstruct communities through an analysis of the current uses of energy and community facilities in rural villages. The results indicated that the consumption of petroleum was highest in mountain villages at an average of 187,475 won/month(), followed by fishing villages at an average of 144,142 won/month() and rural villages at an average of 126,070 won/month(). The rate of utilization of community facilities was reversely highest in rural villages at 84.3%, followed by fishing villages at 61.1% and mountain villages at 40.7%. This research also found that households saved energy when they used community facilities and areas with a high rate of utilization of community facilities at a lower average temperature in winter. It saved approximately 33% energy compared to other areas. Finally, efficient and economical methods for community facilities in villages to be newly developed and the remodeling of existing facilities should been needed in the future to contribute to reconstructing rural village communities that face a crisis of maintenance or abolition.

Laboratory for Electromagnetic Field and Microwave Electronics, ETH Zurich, Zurich 8092, Switzerland(Received January 23, 2014; Revised February 3, 2014; Accepted February 19, 2014)Abstract: We have investigated the optical properties of plamonic waveguide with tapered structure based on InP material for photonic integrated circuit(PIC). The proposed plasmonic waveguide is covered with the Ag thin film to generate the plasmonic wave on metallic interface. The optical characteristics of plasmonic waveguide were calculated using the three-dimensional finite-difference time-domain method. The plasmonic waveguide was fabricated with the lengths of 2 to 10 μm and the widths of 400 to 700 nm, respectively. The plasmonic mode and optical loss were measured. The optimum plasmonic length is 10 μm and widths are 600 and 700 nm in the fabricated waveguide. This plasmonic waveguide can be directly integrated with other conventional optical devices and can be essential building blocks of PIC. Keywords: FDTDSurface plasmon resonance, Plamonic waveguide, Tapered structure, PIC

We demonstrate significant enhancement of an effective Q-factor in a silica planar waveguide-based asymmetric Mach–Zehnder interferometer (AMZI) coupled with a microdisk. To enhance the Q-factor, which is required to more effectively measure the signal changes occurring during biochemical events, the structure utilizes resonance mode splitting. This phenomenon is observed through power cancellation at the same amplitude and a 180° phase difference of each path in the AMZI. In this study, we experimentally showed the effective Q-factor enhancement by comparing resonance characteristics of a fabricated microdisk, AMZI, and the proposed structure at equal fabrication conditions. We measured an effective Q-factor of 9.15 × 104 with a 22 dB extinction ratio.