Recently, interest in technology for eco-friendly energy harvesting has been increasing. Polyvinylidene fluoride (PVDF) is one of the most fascinating materials that has been used in energy harvesting technology as well as micro-filters by utilizing an electrostatic effect. To enhance the performance of the electrostatic effect-based nanogenerator, most studies have focused on enlarging the contact surface area of the pair of materials with different triboelectric series. For this reason, one-dimensional nanofibers have been widely used recently. In order to realize practical energy-harvesting applications, PVDF nanofibers are modified by enlarging their contact surface area, modulating the microstructure of the surface, and maximizing the fraction of the β-phase by incorporating additives or forming composites with inorganic nanoparticles. Among them, nanocomposite structures incorporating various nanoparticles have been widely investigated to increase the β-phase through strong hydrogen bonding or ion-dipole interactions with -CF2/CH2- of PVDF as well as to enhance the mechanical strength. In this study, we report the recent advances in the nanocomposite structure of PVDF nanofibers and inorganic nanopowders.

Layered-double hydroxide (LDH)-based nanostructures offer the two-fold advantage of being active catalysts with incredibly large specific surface areas. As such, they have been studied extensively over the last decade and applied in roles as diverse as light source, catalyst, energy storage mechanism, absorber, and anion exchanger. They exhibit a unique lamellar structure consisting of a wide variety of combinations of metal cations and various anions, which determine their physical and chemical performances, and make them a popular research topic. Many reviewed papers deal with these unique properties, synthetic methods, and applications. Most of them, however, are focused on the form-factor of nanopowder, as well as on the control of morphologies via one-step synthetic methods. LDH nanostructures need to be easy to control and fabricate on rigid substrates such as metals, semiconductors, oxides, and insulators, to facilitate more viable applications of these nanostructures to various solid-state devices. In this review, we explore ways to grow and control the various LDH nanostructures on rigid substrates.

Copper oxide thin films are deposited using an ultrasonic-assisted spray pyrolysis deposition (SPD) system. To investigate the effect of substrate temperature and incorporation of a chelating agent on the growth of copper oxide thin films, the structural and optical properites of the copper oxide thin films are analyzed by X-ray diffraction (XRD), field-emssion scanning electron microscopy (FE-SEM), and UV-Vis spectrophotometry. At a temperature of less than 350 ℃, threedimensional structures consisting of cube-shaped Cu2O are formed, while spherical small particles of the CuO phase are formed at a temperature higher than 400 ℃ due to a Volmer-Weber growth mode on the silicon substrate. As a chelating agent was added to the source solutions, two-dimensional Cu2O thin films are preferentially deposited at a temperature less than 300 ℃, and the CuO thin film is formed even at a temperature less than 350 ℃. Therefore the structure and crystalline phase of the copper oxide is shown to be controllable.

We report the feasibility of TaC production via self-propagating high temperature synthesis, and the influence of the initial green compact density on the final composite particle size. Experiments are carried out from a minimum pressure of 0.3 MPa, the pressure at which the initial green body becomes self-standing, up to 3 MPa, the point at which no further combustion occurs. The green density of the pellets varies from 29.99% to 42.97%, as compared with the theoretical density. The increase in green density decreases the powder size of TaC, and the smallest particle size is observed with 1.5 MPa, at 10.36 μm. Phase analysis results confirm the presence of the TaC phase only. In the range of 0.3-0.5 MPa, traces of unreacted Ta and C residues are detected. However, results also show the presence of only C residue in the matrix within the pressure range of 0.6-3.0 MPa.

Li-incorporated ZnO thin films were deposited by using ultrasonic-assisted spray pyrolysis deposition (SPD) system. To investigate the effect of Li-incorporation on the performance of ZnO thin films, the structural, electrical, and optical properites of the ZnO thin films were analyzed by means of X-ray diffraction (XRD), field-emssion scanning electron microscopy (FE-SEM), Hall effect measurement, and UV-Vis spectrophotometry with variation of the Li concentraion in the ZnO sources. Without incorporation of Li element, the ZnO surface showed large spiral domains. As the Li content increases, the size of spiral domains decreased gradually, and finally formed mixed small grain and one-dimensional nanorod-like structures on the surface. This morphological evolution was explained based on an anti-surfactant effect of Li atoms on the ZnO growth surface. In addition, the Li-incorporation changed the optical and electrical properties of the ZnO thin films by modifying the crystalline defect structures by doping effects.

We investigated a Leidenfrost effect in the growth of ZnO nanostructures on silicon substrates by ultrasonic-assisted spray pyrolysis deposition(SPD). Structural and optical properties of the ZnO nanostructures grown by varying the growth parameters, such as substrate temperature, source concentration, and suction rate of the mist in the chambers, were investigated using field-emission scanning electron microscopy, X-ray diffraction, and photoluminescence spectrum analysis. Structural investigations of the ZnO nanostructures showed abnormal evolution of the morphologies with variation of the substrate temperatures. The shape of the ZnO nanostructures transformed from nanoplate, nanorod, nanopencil, and nanoprism shapes with increasing of the substrate temperature from 250 to 450 °C; these shapes were significantly different from those seen for the conventional growth mechanisms in SPD. The observed growth behavior showed that a Leidenfrost effect dominantly affected the growth mechanism of the ZnO nanostructures.

We investigated the effect of ZnO buffer layer on the formation of ZnO thin film by ultrasonic assisted spray pyrolysis deposition. ZnO buffer layer was formed by wet solution method, which was repeated several times. Structural and optical properties of the ZnO thin films deposited on the ZnO buffer layers with various cycles and at various temperatures were investigated by field-emission scanning electron microscopy, X-ray diffraction, and photoluminescence spectrum analysis. The structural investigations showed that three-dimensional island shaped ZnO was formed on the bare Si substrate without buffer layers, while two-dimensional ZnO thin film was deposited on the ZnO buffer layers. In addition, structural and optical investigations showed that the crystalline quality of ZnO thin film was improved by introducing the buffer layers. This improvement was attributed to the modulation of the surface energy of the Si surface by the ZnO buffer layer, which finally resulted in a modification of the growth mode from three to two-dimensional.

Porous polytetrafluoroethylene (PTFE) thin films are fabricated by spin-coating using a dispersion solution containing PTFE powders, and their crystalline properties are investigated after thermal annealing at various temperatures ranging from 300 to 500°C. Before thermal annealing, the film is densely packed and consists of many granular particles 200-300 nm in diameter. However, after thermal annealing, the film contains many voids and fibrous grains on the surface. In addition, the film thickness decreases after thermal annealing owing to evaporation of the surfactant, binder, and solvent composing the PTFE dispersion solution. The film thickness is systematically controlled from 2 to 6.5 μm by decreasing the spin speed from 1,500 to 500 rpm. A triboelectric nanogenerator is fabricated by spin-coating PTFE thin films onto polished Cu foils, where they act as an active layer to convert mechanical energy to electrical energy. A triboelectric nanogenerator consisting of a PTFE layer and Al metal foil pair shows typical output characteristics, exhibiting positive and negative peaks during applied strain and relief cycles due to charging and discharging of electrical charge carriers. Further, the voltage and current outputs increase with increasing strain cycle owing to accumulation of electrical charge carriers during charge-discharge.

We report on an all-solution-processed hydrothermal method to control the morphology of ZnO nanostructures on Si substrates from three-dimensional hemispherical structures to two-dimensional thin film layers, by controlling the seed layer and the molar contents of surfactants during their primary growth. The size and the density of the seed layer, which is composed of ZnO nanodots, change with variation in the solute concentration. The ZnO nanodots act as heterogeneous nucleation sites for the main ZnO nanostructures. When the seed layer concentration is increased, the ZnO nanostructures change from a hemispherical shape to a thin film structure, formed by densely packed ZnO hemispheres. In addition, the morphology of the ZnO layer is systematically controlled by using trisodium citrate, which acts as a surfactant to enhance the lateral growth of ZnO crystals rather than a preferential one-dimensional growth along the c-direction. X-ray diffraction and energy dispersive X-ray spectroscopy results reveal that the ZnO structure is wurtzite and did not incorporate any impurities from the surfactants used in this study.

We report on the successful fabrication of ZnO nanorod (NR)/polystyrene (PS) nanosphere hybrid nanostructure by combining drop coating and hydrothermal methods. Especially, by adopting an atomic layer deposition method for seed layer formation, very uniform ZnO NR structure is grown on the complicated PS surfaces. By using zinc nitrate hexahydrate [Zn(NO3)2 ·6H2O] and hexamine [(CH2)6N4] as sources for Zn and O in hydrothermal process, hexagonal shaped single crystal ZnO NRs are synthesized without dissolution of PS in hydrothermal solution. X-ray diffraction results show that the ZnO NRs are grown along c-axis with single crystalline structure and there is no trace of impurities or unintentionally formed intermetallic compounds. Photoluminescence spectrum measured at room temperature for the ZnO NRs on flat Si and PS show typical two emission bands, which are corresponding to the band-edge and deep level emissions in ZnO crystal. Based on these structural and optical investigations, we confirm that the ZnO NRs can be grown well even on the complicated PS surface morphology to form the chestnut-shaped hybrid nanostructures for the energy generation and storage applications

We report on the succesful fabrication of ZnO nanorod (NR)-based robust piezoelectric nanogenerators(PNGs) by using Cu foil substrate. The ZnO NRs are successfully grown on the Cu foil substrate by using all solutionbased method, a two step hydrothermal synthesis. The ZnO NRs are grown along c-axis well with an average diameterof 75~80 nm and length of 1~1.5 µm. The ZnO NRs showed abnormal photoluminescence specrta which is attributedfrom surface plasmon resonance assistant enhancement at specific wavelength. The PNGs on the SUS substrates showtypical piezoelectric output performance which showing a frequency dependent voltage enhancement and polarity depen-dent charging and discharging characteristics. The output voltage range is 0.79~2.28 V with variation of input strain fre-quency of 1.8~3.9 Hz. The PNG on Cu foil shows reliable output performance even at the operation over 200 timeswithout showing degradation of output voltage. The current output from the PNG is 0.7 µA/cm2 which is a typical out-put range from the ZnO NR-based PNGs. These performance enhancement is attributed from the high flexibility, highelectrical conductivity and excellent heat dissipation properties of the Cu foil as a substrate.

본 연구는 제외국의식중독균별저감화사례를조사, 비교하여 정보를 획득하고 식중독균 저감화 매뉴얼을 작성하며 저감화 정책방안을 제시하기 위한 기반 자료 확보를 목적 으로 수행하였다. 선진 외국(미국, 덴마크, 일본)의 식중독 저감화 정책의 현황 및 사례조사에는 인터넷 자료, 관련 기관 전문가 인터뷰를 통하여 조사하였다. 미국의 신선농산물에서 미생 물학적 위험요소 저감화(FDA), 미국 분쇄쇠고기에서 E. coli O157:H7의 저감화(USDA), 덴마크의 닭고기, 돼지고기, 계란에서 살모넬라 저감화, 일본의 어패류에서 장염비 브리오 저감화 프로그램을 사례 연구로 제시하였으며 이들 국가의 저감 프로그램의 배경, 전략, 효과를 조사하고 장단점 분석을 실시하고 시사점을 도출하였다. 이들 제외 국 정책 사례 연구와 국제기구 CODEX의 위해관리 체계 를 결합하고 국내 현실을 반영하여 식중독 저감화 관리 매뉴얼로 저감 프로그램에 관한 일반 모델을 다음 순서로 제시하였다: 1) 위해관리 초기판단, 2) 식중독 저감화 프 로그램 계획, 3) 대안 확인 및 선택, 4) 대안 실행(이해당 사자별 역할 설정 및 대안 방법 적용), 5) 감시 활동, 6) 중간 재검토, 7) 목적 달성 때까지 대안 실행 지속적 실시 (만일 대안이 효과가 없으면 대안을 대체하거나 수정하여 식중독 저감화 목표 달성 시까지 실시), 8) 최종 평가에 보건에 미치는 영향을 확인하고 필요시 비용 편익 분석 실시. 본 연구를 통해서 제시된 식중독 저감화 정책에 관한 시사점 및 식품안전의 이해당사자별 역할별로 도출된 식 중독 저감화 정책 모델 및 매뉴얼은 미생물학적 위해관리를 수행하는데 향후 활용될 수 있다.

This study was performed to acquire the information on the foodborne pathogen risk management programs in a couple of developed countries by the expert meeting and searching the information on the web. The backgrounds, strategies and effects related to microbial hazards of the foodborne pathogen reduction programs in fresh produce (US), Escherichia coli O157:H7 in ground beef (US), Salmonella in chicken, pork and eggs (Denmark), and Vibrio parahaemolyticus in seafood (Japan) were investigated for case study. A comparison among the pathogen reduction programs was conducted to find advantages and disadvantages and implications of the policies to bring out implications of the programs. A model for foodborne pathogen reduction program was developed based on both the CODEX risk management scheme and the case studies as follows; 1) preliminary risk management activities, 2) planing a foodborne pathogen reduction program, 3) option identification and selection, 4) implementation (conducting the each stake-holders role and applying the intervention methods), 5) monitoring activities, 6) interim review, 7) continuation or amendment of implementation method by the interim review before achieving the goal, and 8) final review and additional cost-benefit analysis if necessary. This proposed model according to the role of the stake-holders can be used to conduct microbial risk management programs in Korea in the near future.

The purpose of this study was to verify the change in temperature·humidity·perspiration of fire suit when applying phased intensive exercises to fire fighter wearing fire suit. For this study, three male fire fighters took basic physical test and performed 10 minute phased intensive exercises -exercise intensity I (30%VO2max), exercise intensity II (45%VO2max), exercise intensity III (60%VO2max) based on maximum oxygen consumption (VO2max)- wearing fire suit (helmet, boots, air respirator) in treadmill and took a rest. The result of study shows that the temperature in the suit elevated during stabilization period after each exercise intensity, humidity elevated as exercise intensity increased, perspiration elevated as exercise intensity increased.

The purpose of this study was to verify the relationship between fire fighter's musculoskeletal disorder related observable symptom and their absence from disease and accident. Online questionnaire was distributed with a total of 7,673 fire fighters, and statistical analysis was conducted to the collected data. The result shows that on a one year basis, patients with musculoskeletal disorder related observable symptom felt symptom in sequence of back, shoulder, neck, knee. The result verified that 12.9% of absence of disease and 5.9% of absence of accident experienced these symptoms. Both absence from disease and absence from accident showed body part symptoms related to neck and shoulder. This study ascertained the relationship between fire fighters' absence and their musculoskeletal disorder related observable symptom. The author hopes this study to be used as a basis of precautionary program for absence management.

Al-doped ZnO(AZO) thin films were synthesized using atomid layer deposition(ALD), which acurately controlledthe uniform film thickness of the AZO thin films. To investigate the electrical and optical properites of the AZO thin films,AZO films using ALD was controlled to be three different thicknesses (50nm, 100nm, and 150nm). The structural, chemical,electrical, and optical properties of the AZO thin films were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy,field-emssion scanning electron microscopy, atomic force microscopy, Hall measurement system, and UV-Visspectrophotometry. As the thickness of the AZO thin films increased, the crystallinity of the AZO thin films gradually increased,and the surface morphology of the AZO thin films were transformed from a porous structure to a dense structure. The averagesurface roughnesses of the samples using atomic force microscopy were ~3.01nm, ~2.89nm, and ~2.44nm, respectively. Asthe thickness of the AZO filmsincreased, the surface roughness decreased gradually. These results affect the electrical and opticalproperties of AZO thin films. Therefore, the thickest AZO thin films with 150nm exhibited excellent resistivity (~7.00×10−4Ω·cm), high transmittance (~83.2%), and the best FOM (5.71×10−3Ω−1). AZO thin films fabricated using ALD may be usedas a promising cadidate of TCO materials for optoelectronic applications.