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We report the microstructure and thermoelectric properties of composite nanofiber webs, which were fabricated by dual-electrospinning of polyacrylonitrile (PAN) and sodium cobalt oxide (NaCo2O4) precursor solutions with different input compositions and following heat-treatment at 600–900 °C for simultaneous carbonation and calcination. The SEM and EDS mapping images revealed that PAN-derived carbon nanofibers (CNFs) and NaCo2O4-based ceramic nanofibers coexisted in the composite nanofiber webs and that their relative contents could be controlled by the input compositions. The Seebeck coefficient increased from ~26.77 to ~73.28 μV/K and from ~14.83 to ~40.56 μV/K with increasing the relative content of NaCo2O4 nanofibers in the composite nanofiber webs fabricated at 700 and 800 °C, respectively. On the other hand, the electrical conductivity of the composite nanofiber webs increased with the decrement of the relative content of NaCo2O4 nanofibers as well as the increment of the heat-treatment temperature. Owing to the opposite contributions of NaCo2O4 nanofibers and CNFs to the Seebeck coefficient, electrical conductivity and thermal conductivity, a maximum power factor of ~5.79 μW/mK2 and a figure of merit of ~0.01 were attained for CNF/NaCo2O4-based composite nanofiber webs fabricated at 45 wt% input composition of NaCo2O4 and at heat-treatment of 700 °C.

Nurses with rotating shifts, including night shifts, have suffered from low physical activity during the COVID-19 pandemic and lower sleep quality due to the disruption of their circadian rhythm. This study aimed to develop and examine the effectiveness of a mobile wellness program on daily steps, sleep quality, exercise self-efficacy, intrinsic motivation for exercise, self-rated fatigue, and wellness. A cluster randomized controlled trial design was used to examine the effectiveness of the mobile wellness program for nurses with rotating shifts. Sixty nurses from one university hospital participated and were allocated to an intervention group and a control group. The intervention group received a 12-week mobile wellness program to improve their physical activity and sleep quality, and the control group was only given a Fitbit to self-monitor their health behaviors. There were significant differences between the two groups in daily steps (p = 0.000), three components (subjective sleep quality, sleep disturbance, daytime dysfunction) of the PSQI, exercise self-efficacy, intrinsic motivation for exercise, and wellness. In conclusion, this study provides meaningful information that the mobile wellness program using Fitbit, online exercise using Zoom, online health coaching on a Korean mobile platform, and motivational text messages effectively promoted physical activity and sleep quality for nurses with rotating shifts during the COVID-19 pandemic.

In this study, we prepared a thermoelectric device with p-type organic thermoelectric hybrid film and n-type buckypaper. Both the film and buckypaper are made of a hybrid filler of graphite nanoplatelets (GNPs) and single-walled carbon nanotubes (SWNTs). The p-type thermoelectric hybrid film has a free-standing form and enhanced thermoelectric performance owing to a polyvinylidene fluoride/carbon hybrid film purified with an acid solution, which successfully eliminates amorphous carbon, additives, and impurities. The n-type thermoelectric buckypaper was made with a filtration method with GNPs and SWNTs to the membrane filter. To convert this to an n-type thermoelectric property, a polyethyleneimine solution was also added by filtration process. In addition, adding sodium dodecyl benzene sulfonate during carbon dispersion enhanced thermoelectric performance, which was confirmed by measuring the electrical conductivity and Seebeck coefficient. A thermoelectric device using silver electrodes was produced with the thermoelectric composite film and buckypaper to verify its thermoelectric voltage and generating power.

This study investigates a post treatment method for improving the thermoelectric properties of carbon nanotube (CNT)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) nanocomposite films. Ethylene glycol (EG) treatment is performed by immersing the as-prepared CNT/PEDOT:PSS nanocomposite films in EG for 1 h followed by annealing at 140 °C for 10 min. Non-complexed PSS chains could be effectively removed using the EG treatment, resulting in a decrease in inter-bundle distances in the nanocomposite films. This drastically increases the electrical conductivity of the PEDOT:PSS matrix. EG-treated nanocomposite films with 20 wt% CNTs exhibited the highest power factor of 151 ± 34 μW m−1 K−2 among all the prepared samples. Our results indicate that the EG treatment is a promising method for fabricating cost-effective, high-performance thermoelectric CNT/PEDOT:PSS nanocomposite films. We fabricated an organic thermoelectric generator using EG-treated CNT/PEDOT:PSS nanocomposite patterns and evaluated its electric power generation capabilities.

The influence of film thickness and crystallinity of poly(3-hexylthiophene) (P3HT) on the thermoelectric properties of doped P3HT films was systematically investigated. To obtain excellent thermoelectric properties, highly crystalline P3HT films were prepared by simple wire-bar-coating. The P3HT films doped with a ferric chloride exhibited power factors of up to 35.0 μW m−1 K−2 at room temperature. This study suggests that it could be possible to optimize the thermoelectric properties of the conjugated polymer films by controlling the film thickness and polymer structure. Further, the processing method and conjugated polymers selected for thermoelectric applications should be considered carefully because they determine the final characteristics of the films produced.

We studied the thermoelectric properties of a diketopyrrolopyrrole-based semiconductor (PDPP3T) via a precisely tuned doping process using Iron (III) chloride. In particular, the doping states of PDPP3T film were linearly controlled depending on the dopant concentration. The outstanding Seebeck coefficient of PDPP3T assisted the excellent power factors (PFs) over 200 μW m−1K−2 at the broad range of doping concentration (3–8 mM) and the maximum PF reached up to 276 μW m−1K−2, which is much higher than that of poly(3-hexylthiophene), 56 μW m−1K−2. The high-mobility of PDPP3T was beneficial to enhance the electrical conductivity and the low level of total dopant volume was important to maintain high Seebeck coefficients. In addition, the low bandgap PDPP3T polymer effiectively shifted its absorption into near infra-red area and became more colorless after doping, which is great advantage to realize transparent electronic devices. Our results give importance guidance to develop thermoelectric semiconducting polymers and we suggest that the use of low bandgap and high-mobility polymers, and the accurate control of the doping levels are key factors for obtaining the high thermoelectric PF.

The fabrication of an active-matrix liquid-crystal display by using printing processes offers the potential to reduce the number of photolithography steps and the manufacturing costs. In this study, we prepare the indium-zinc-oxide (IZO) thin-film transistors (TFTs) by using non-vacuum processes such as inkjet printing. The self-assembled monolayers of hexadecanethiol (HDT) on the surface of the oxide semiconductor prior to the inkjet printing of Ag were employed to modify the electric barrier between the IZO and the printed Ag. The field-effect mobility of the IZO TFTs with 0.5-mM HDT treatments and with the inkjet-printed Ag electrodes that were investigated by using their current-voltage characteristics was approximately 0.36 cm2/Vs.

We prepared a poly(imide-benzoxazole) gate insulator for solution-processed flexible metal oxide thin-film transistors (TFTs). The electrical insulating property of the poly(imide-benzoxazole) gate insulator is maintained up to at least 350 °C. The 350 °C-annealed indium-zinc oxide (IZO) TFT with the poly(imide-bezoxazole) gate insulator showed excellent TFT performance with the field-effect mobility of 9.2 cm2 V−1 s−1 and the on/off current ratio of 1.5 × 106. A flexible IZO TFT with the poly(imide-bezoxazole) gate insulator was also fabricated directly on a flexible Kapton substrate. The flexible IZO TFT with the poly(imide-bezoxazole) gate insulator could be operated during bending. Before bending, the mobility and on/off current ratio were 4.1 cm2 V−1 s−1 and 4.7 × 105, respectively. During bending with a radius of 10 mm, the mobility was maintained and the on/off current ratio was slightly decreased to 3.2 × 105.

*, **Department of Architecture & Ocean Space, Korea Maritime University, Busan 606-791, Korea †Department of Oceanic Architectural Eng., Graduate School, Korea Maritime University, Busan 606-791, Korea요 약 :최근 해상을 비롯한 수상공간에 다양한 플로팅 건축물이 계획되거나 설치되고 있다. 그러나 관련 법제도의 미비로 인하여 플로팅 건축물의 설계 및 건설 혹은 관리운영에서 많은 문제점이 발생되고 있으며 이는 플로팅 건축물의 활성화를 저해하는 중요한 요인이 되고 있다. 따라서 본 연구에서는 플로팅 건축물에 대한 국내 법제도 적용 사례 및 해외 관련 법제도 사례 조사를 실시하여 우리나라에서 플로팅 건축물의 법제도 개선을 위한 기초자료와 개선방향을 제시하였다. 연구결과 플로팅 건축물은 선박이 아닌 건물로서 법적 지위를 확보하며 플로팅 건축물 설치 특별구역을 설정하여 건물의 대지를 조성하고 별도 기술기준을 적용하며 건축인허가 및 등기 절차를 활용할 수 있도록 법제도 개선이 필요하다.핵심용어 : 플로팅 건축물, 건축법, 법제도개선, 사례연구, 국내외사례 Abstract : Recently many different floating buildings are planed and constructed in the sea, river, etc. for active use of water spaces. But many problems are occurred in the process of floating building design, construction and management due to the inadequate legal system. This incomplete legal system has become one of the critical factors which are hampering the invigoration of floating buildings. Therefore this study is to suggest preliminary data and improvement directions through a case study with domestic and foreign examples of appropriate laws and law applications concerning floating buildings. As the results of this study the laws related to floating building have to be revised in the directions of qualifying legally floating building as 'building' but not 'ship', designating 'special zone' for floating building site, and applying the established 'building licensing procedure' to floating building also. Key words :floating building, building law, legal system improvement, case study, domestic and foreign examples * 대표저자: 종신회원, hansk@hhu.ac.kr 051)410-4581 ** 연회원, mklee@hhu.ac.kr 051)410-4584 †교신저자: 연회원, hun0707@hhu.ac.kr 051)410-4995 (주) 이 논문은 2011년 한국항해항만학회 추계학술대회에서 “플로팅 건축물 법제도 사례 연구”로 발표된 것을 발전시켜 정리한 것임.

The systematic criteria and rational standard for site selection of marine recreational floating architecture are in urgently need in respect of structural safety, use of facilities, economics of construction and management, relationship with surrounding areas or cities and impact on marine environment. Nevertheless, at present, there is not any study nor guideline for site selection of marine recreational floating architecture which is now being planned and elected at many places of a body of water such as river or coastal area all over the country. Therefore this study is to propose a systematic process and a rational criteria and guideline for site selection of marine recreational floating architecture. Especially the results are suggested in forms of diagrams and tables in order to be utilized so easily by related local governments and individual enterprises.

Transparent conductive 5 at.% Ga -doped ZnO (GZO) thin films are deposited on a glass substrate by an asymmetrical bipolar-pulsed DC magnetron sputtering at various substrate temperatures. All the GZO films have nanocrystalline structure and compact surface morphology. A highly c-axis oriented GZO film was grown perpendicular to the substrate at the 200C. The measured work function of GZO film deposited at 200°C shows slightly lower value of 4.37 eV than a commercial ITO film of 4.6 eV. The GZO film showed the lowest sheet resistance of 35 Ω/□, a carrier concentration of 1.2 ×1021 cm -3, a mobility of 9.9 cm2/Vs, and high optical transmittance of over 85% in the visible range. It indicates that the GZO films at 200°C can be promising as an alternative to ITO thin film for transparent electrode applications.

The thermoelectric properties of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and tellurium-PEDOT:PSS (Te-PEDOT:PSS) hybrid composites were enhanced via simple chemical treatment. The performance of thermoelectric materials is determined by their electrical conductivity, thermal conductivity and Seebeck coefficient. Significant enhancement of the electrical conductivity of PEDOT:PSS and Te-PEDOT:PSS hybrid composites from 787.99 and 11.01 to 4839.92 and 334.68 S cm−1, respectively was achieved by simple chemical treatment with H2SO4. The power factor of the developed materials could be effectively tuned over a very wide range depending on the concentration of the H2SO4 solution used in the chemical treatment. The power factors of the developed thermoelectric materials were optimized to 51.85 and 284 μW m−1 K−2, respectively, which represent an increase of four orders of magnitude relative to the corresponding parameters of the untreated thermoelectric materials. Using the Te-PEDOT:PSS hybrid composites, a flexible thermoelectric generator that could be embedded in textiles was fabricated by a printing process. This thermoelectric array generates a thermoelectric voltage of 2 mV using human body heat.

Resist-free antireflective (AR) nanostructured films are directly fabricated on polycarbonate (PC) film using thermal-nanoimprint lithography (T-NIL) and the moth-eye shape of AR nanostructure is elaborately optimized with different oxygen reactive ion etching conditions. Anodic aluminum oxide (AAO) templates are directly used as master molds of T-NIL for preparation of AR nanostructures on PC film without an additional T-NIL resist. AR nanostructures are well arranged with a period of about 200 nm and diameter of about 150 nm, which corresponds to those of the AAO template mold. The moth-eye AR nanostructures exhibit the average reflectance of 2% in wavelength range from 400 to 800 nm. From the results, highly enhanced AR properties with simple direct imprinting on PC film demonstrate the potential for panel application in the field of flat display, touch screen, and solar cells.