항공기는 대표적인 인간-기계시스템이다. 인간의 조작과 기계의 작동 완료 시점 사이에는 기계가 작동되기 시작하 는 시간과 기계에 힘이 전달되기 시작하여 완료되는 시간 등의 지연이 발생하며 항공기 조종은 시스템의 지연을 예 측한 타이밍 작업을 통해 이루어진다. 시간지각은 타이밍 작업의 중요한 요소이며, 높은 각성작용과 관련된 불안에 영향을 받는 것으로 알려져 있다. 본 연구는 가상현실 환경에서 현직 조종사를 대상으로 기상, 비행 및 시간 조건이 조종사에게 발생하는 불안과 시간지각에 미치는 영향을 검증하였다. 기상조건은 시계비행 기상 상황과 악기상 상황 으로 구분하였고 비행 및 시간 조건을 달리하여 실험 1, 2를 실시하였다. 실험 1은 비교적 운동량의 변화가 적고 지연이 적은 제자리비행과 수평비행 상황에서 조종간에 추가된 버튼을 사용하여 시간지각을 측정하였다. 실험 2는 운동량의 변화가 많고 지연이 많이 발생하는 이륙상황에서 조종간만을 사용하게 하여 자연스럽게 헬리콥터를 이륙 시키는 과정에서 시간지각을 측정하였다. 실험결과 악기상 상황에서 불안과 심박수가 증가하는 것으로 나타났으며, 특히 실험 1, 2의 모든 비행조건 중 불안이 증가한 상황에서 시간을 과대 추정하는 것으로 나타났다. 이 결과는 불안 의 영향으로 시간을 과대 추정하여 타이밍 작업을 실패할 수 있으며, 이로 인해 조종에 어려움을 겪고 사고로 연결될 가능성이 있음을 시사한다.

목적 : 온열 안구 마사지기 사용 시 실시간으로 눈꺼풀 온도 및 눈물막 파괴 시간을 측정하여 차이를 평가하고 자 하였다. 방법 : 연구 대상은 성인 30명 (23.7±2.60세)을 대상으로 하였고 OSDI설문지 점수에 따라 건성안 그룹과 정 상안 그룹으로 나누었다(건성안 15명, 정상안 15명). 온열 안구 마사지기는 OA-MA011(OA, Seoul, Korea), OA-MA 030(OA, Seoul, Korea), DP-EM50(Caremedi, Hanam, Korea)를 사용하였고, A400 열화상카메라 (FLIR, Wilsonville, Clackamas County USA) 사용하여 착용 전과 후 1, 3, 5, 10, 15분 측정하고, 탈거 후 5, 10, 15분 시간별로 측정 후 평균값을 기록하였다. 그리고 Kekatography 5 m(OCULUS, Wetzlar, Germany)를 사용하여 마사지기 착용하기 전과 착용 15분 뒤에 눈물막 파괴 시간을 측정해서 비교 분석하였다. 결과 : 15분 착용 시 눈꺼풀 온도는 건성안 그룹은 39.77±0.69℃, 정상안 그룹은 39.57±0.77℃ 측정되었 으며, 눈꺼풀 온도 측정 시 건성안, 정상안 그룹 모두 5분 이상 착용 시 통계적으로 유의성이 있었다(p=0.033). 눈물막 파괴시간은 착용하기 전보다는 향상이 있었지만 정상범위에 못 미치는 것으로 확인하였고 건성안에서는 통 계적으로 유의성이 있었지만(p=0.041) 정상안 그룹에서는 통계적으로 유의성이 없었다(p=0.084). 결론 : 안구건조증으로 인한 개선 방법으로 안구마사지기를 사용했을 때 10분 이상 착용 시 눈꺼풀 높은 온도 에서 유지가 되었고 눈물막 파괴 시간은 15분 이상 착용 및 온도 40℃ 유지 시 눈물막 파괴 시간에 영향을 줄 수 있었다. 따라서 온열 기능의 마사지기를 사용 시 정확한 사용 방법과 눈꺼풀 온도가 유지되며 착용 시간은 충분한 상태에서 진행해야 할 것으로 사료 된다.

목적 : 본 연구는 실제 골프장과 여러 색상의 골프공 이미지로 만들어진 파워포인트와 안구 추적기를 이용하여 물체의 색상에 따른 시인성과 안구 주시 시간을 확인해보고자 하였다. 방법 : 본 연구는 총 20명(평균연령: 24.9±1.99세, 남자: 11명, 여자: 9명)을 대상으로 진행하였다. 골프장 이미지와 동영상, 여러 색상의 골프공을 이용하여 파워포인트를 만든 후 실험실에 빔 프로젝터를 투사한 뒤 Eye tracker glasses 2(Tobii, Danderyds, Stockholms, Sweden)를 착용시키고 이미지 내의 공을 찾도록 지시하였 다. 인지한 공의 개수, 시간, 순서 등을 측정하였다. 결과: 제한시간 동안 찾은 공의 개수는 하얀색 공 4.70±0.68, 주황색 공 4.52±0.84, 파란색 공 4.12±0.75, 형광색 공 4.90±0.37개였다(p<0.010). 모든 공을 인지하기까지 걸린 시간은 하얀색 6.77±2.37, 주황색 7.61± 2.18, 파란색 9.50±0.96, 형광색 5.18±2.05초였다(p<0.010). 서로 다른 색상의 공이 배치된 이미지와 동영상에서 인지한 순서를 측정한 결과 이미지에서는 형광색(40.00%)을 가장 먼저 인지하였고, 파란색(48.75%)을 가장 늦게 인지하였다(p<0.050). 동영상에서는 형광색(40.00%)을 가장 먼저 인지하였고, 파란색(50.00%)을 가장 늦게 인지하였 다(p<0.050). 공이 날아가도록 연출된 이미지에서 인지한 공의 개수는 하얀색 공 1.90±0.85, 주황색 공 2.25±1.06, 파란색 공 1.50±0.68, 형광색 공 3.10±0.71개였다(p<0.010). 결론 : 본 연구 결과, 푸른 잔디 배경에서 모든 색상의 공은 다른 시인성을 보였고 형광색의 공이 시인성이 가 장 높게 나타났으며, 파란색의 공이 가장 시인성이 낮다는 결과를 보였다. 색 인지를 위한 주시 시간은 형광색이 가장 짧고, 파란색이 가장 길게 측정되었다. 시인성이 낮을수록 색을 인지하기 위한 주시 시간은 높아지는 음의 상관관계를 보였다.

목적 : 대학생을 대상으로 디지털기기의 사용시간을 조사하고, 비침습적 눈물막파괴시간(NITBUT)을 측정하여 디지털기기가 눈물막에 미치는 영향을 알아보고자 하였다. 방법 : 2022년 8월부터 2개월간 충남 소개 대학에 재학 중인 대학생 55명을 대상으로 분석하였다. 눈물막 평 가는 Cornea 550을 이용하여 NITBUT를 측정하여 안구건조증과 정상안으로 구분하였다. 설문은 대상자의 일반 적 특성, 디지털기기의 사용 환경, 그리고 안구건조증 관련 자각 증상에 관해 총 14문항을 조사하였다. 결과 : 대상자들이 디지털기기를 사용하는 시간은 하루 평균 9.93±4.90시간이었다. 하루에 디지털기기를 8 시간 이상 사용하는 그룹에서 NITBUT가 안구건조증에 속한 경우는 58.5%였고, 8시간 미만의 21.4% 보다 유의 하게 높았다(p=0.029). 또한, 하루에 8시간 이상 디지털기기를 사용한 대상자들은 눈의 건조감과 안정피로를 더 크게 호소하였고, 연령, 성별, 콘택트렌즈, 굴절수술, 흡연, 수면시간을 보정한 후에 8시간 이상의 디지털기기의 사용은 안구건조증에 걸릴 확률을 5.18배 높였다(p=0.023). 디지털기기가 스마트폰인 경우는 NITBUT가 정상인 그룹에서 53.8%였고, 안구건조증 그룹에서는 69.0%였다(p>0.050). 결론 : 디지털기기의 사용시간이 8시간 이상 일 경우에는 비침습적 눈물막파괴시간이 짧아졌고, 안구건조증에 걸릴 확률이 높아짐을 확인할 수 있었다.

Considering the non-linear behavior of structure and soil when evaluating a nuclear power plant's seismic safety under a beyond-design basis earthquake is essential. In order to obtain the nonlinear response of a nuclear power plant structure, a time-domain SSI analysis method that considers the nonlinearity of soil and structure and the nonlinear Soil-Structure Interaction (SSI) effect is necessary. The Boundary Reaction Method (BRM) is a time-domain SSI analysis method. The BRM can be applied effectively with a Perfectly Matched Layer (PML), which is an effective energy absorbing boundary condition. The BRM has a characteristic that the magnitude of the response in far-field soil increases as the boundary interface of the effective seismic load moves outward. In addition, the PML has poor absorption performance of low-frequency waves. For this reason, the accuracy of the low-frequency response may be degraded when analyzing the combination of the BRM and the PML. In this study, the accuracy of the analysis response was improved by adjusting the PML input parameters to improve this problem. The accuracy of the response was evaluated by using the analysis response using KIESSI-3D, a frequency domain SSI analysis program, as a reference solution. As a result of the analysis applying the optimal PML parameter, the average error rate of the acceleration response spectrum for 9 degrees of freedom of the structure was 3.40%, which was highly similar to the reference result. In addition, time-domain nonlinear SSI analysis was performed with the soil's nonlinearity to show this study's applicability. As a result of nonlinear SSI analysis, plastic deformation was concentrated in the soil around the foundation. The analysis results found that the analysis method combining BRM and PML can be effectively applied to the seismic response analysis of nuclear power plant structures.

The Cheonggukjang used in this study was made with four soybean cultivars grown and harvested at the National Agrobiodiversity Center of the National Academy of Agricultural Sciences: C1 (KLS87248), C2 (Nongrim 51), C3 (GNU- 2007-14613), and C4 (Daewon). The soybeans were inoculated with Bacillus subtilis AFY-2 and fermented for 0, 12, 21, 36, 45, and 60 h in a culture room at 35°C. ABTS and DPPH radical scavenging activities were significantly increased upon fermentation for 12 hours in all samples and maintained or decreased after 21 hour The inhibition of NO production was significantly increased compared to the LPS-treated group, and the C2 sample showed inhibition of NO production at 12 hours of fermentation, and the C3 sample showed inhibition at 21 hours of fermentation. PCA analysis revealed that the ABTS and DPPH radical scavenging activity and NO production inhibitory activity reached peak levels around 12 h fermentation time for all samples. Our results indicate that the optimal fermentation time of the Cheonggukjang sample is 12 hours, confirming the high correlation of all experiments.

In recent years, macroalgal bloom occurs frequently in coastal oceans worldwide. It might be attributed to accelerating climate change. “Green tide” events caused by proliferation of green macroalgae (Ulva spp.) not only damage the local economy, but also harm coastal environments. These nuisance events have become common across several coastal regions of continents. In Korea, green tide incidences are readily seen throughout the year along the coastlines of Jeju Island, particularly the northeastern coast, since the 2000s. Ulva species are notorious to be difficult for morphology-based species identification due to their high degrees of phenotypic plasticity. In this study, to investigate temporal variation in Ulva community structure on Jeju Island between 2015 and 2020, chloroplast barcode tuf A gene was sequenced and phylogenetically analyzed for 152 specimens from 24 sites. We found that Ulva ohnoi and Ulva pertusa known to be originated from subtropical regions were the most predominant all year round, suggesting that these two species contributed the most to local green tides in this region. While U. pertusa was relatively stable in frequency during 2015 to 2020, U. ohnoi increased 16% in frequency in 2020 (36.84%), which might be associated with rising sea surface temperature from which U. ohnoi could benefit. Two species (Ulva flexuosa, Ulva procera) of origins of Europe should be continuously monitored. The findings of this study provide valuable information and molecular genetic data of genus Ulva occurring in southern coasts of Korea, which will help mitigate negative influences of green tide events on Korea coast.

목적 : 본 연구에서는 2019년 생활시간조사 자료를 분석 대상으로 작업치료 분야에서 최초로 작업연결망 (occupational network)을 구성하여 전기고령자와 후기고령자의 24시간 작업(occupation)들 간의 관계 를 분석하여 특성을 분석하고 파악하는데 목적이 있다. 연구방법 : 분석 대상은 통계청의 2019년 생활시간조사 자료의 전기고령자 331명과 후기고령자 331명의 24시 간 행동 항목들을 키워드 네트워크 분석 방법으로 분석하여 작업연결망(occupational network)을 구성하고 네트워크 분포의 지표로서 고립 정도, 밀도, 포괄성과 연결 중심성, 근접 중심성을 NetMiner 4.0으로 분석하였 다. 일반적 특성은 SPSS ver.25.0으로 독립표본 t 검정(two-sample t-test), 기술통계를 실시하였다. 결과 : 네트워크 분포 분석결과 전기고령자와 후기고령자의 밀도는 0.793, 0.649, 포괄성은 100%로 나타 났으며, 평균 거리는 1.207, 1.351이며, 고립된 노드는 나타나지 않았다. 중심성 지표 분석 결과 연결 중심성과 근접 중심성이 높은 작업으로는 전기고령자는 교제활동, 스포츠 및 레포츠, 미디어를 이용한 여가활동, 음식준비, 개인위생 및 외모 관리, 후기고령자 미디어를 이용한 여가활동, 개인위생 및 외모관 리, 식사 및 간식 섭취, 수면, 청소 및 정리 순으로 나타났다. 결론 : 본 연구는 2019년 생활시간 조사 자료를 키워드 네트워크 분석 방법을 적용하여 최초로 작업연결 망을 구성하여 전기고령자와 후기고령자 집단 간의 작업 수행의 차이를 분석하고 시각적으로 파악하여 제시 및 분석하였다는 점에 학문적인 의의를 가지며, 이를 통해 작업치료 분야에서 사회연결망 분석 방 법을 사용할 수 있도록 기초자료로 활용할 수 있을 것이다.

PURPOSES : The objective of this study is to analyze the significance of binder aging in a hot-mix asphalt (HMA) mixture in an insulated camber for a long duration for repair works, where the absolute viscosity level and service life reduction (SLR) are assessed based on the haul time, as well as to suggest a methodology for reducing the aging level. METHODS : Because the HMA mixture is stored in an insulated box carriage at high temperature for repair works, if the binder in the mix is severely oxidized, then the repaired pavement will not exhibit a long service life. Therefore, the 13-mm dense-graded HMA mix with PG64-22 was aged in an oven at 160 °C for 1, 2, 4 and 8 h to evaluate its aging level. Gel-permeation chromatography was performed on the mixture particle without binder recovery to measure the large-molecular size ratio, from which the estimated absolute viscosity (EAV) was computed using a best-fit regression model. The SLR values of aged and repaired mixes were estimated to determine the amount of deterioration in the mixes caused by severe aging. Hydrated lime (HL) was introduced into the mix at a ratio of 1.5 wt% of the total mix. The aging level and SLR were compared with those of the repaired mix without HL. RESULTS : The binder EAV of the HMA mix increases significantly with the mixture aging duration. In particular, the binder EAV level of a 4-h aged mix is similar to the asphalt viscosity level of a pavement with approximately 7 years of service life. The service life expressed based on the aging level is interpreted as the reduced service life of the aged mix, which is already oxidized before it is used. Meanwhile, the binder of an 8-h aged mix without HL aged significantly and its SLR is approximately 11 years. However, its aging level and SLR reduced significantly when HL. is incorporated. CONCLUSIONS : The binder aging level of the repaired mix increases significantly with its storage duration in a hot chamber for carriage. However, since the aging level decreases significantly by the incorporation of HL, the use of HL is highly recommended when preparing new mix for repair works to be performed in a hot-chamber for a long duration.

The Cu2ZnSn(SxSe1-x)4 (CZTSSe) absorbers are promising thin film solar cells (TFSCs) materials, to replace existing Cu(In,Ga)Se2 (CIGS) and CdTe photovoltaic technology. However, the best reported efficiency for a CZTSSe device, of 13.6 %, is still too low for commercial use. Recently, partially replacing the Zn2+ element with a Cd2+element has attracting attention as one of the promising strategies for improving the photovoltaic characteristics of the CZTSSe TFSCs. Cd2+ elements are known to improve the grain size of the CZTSSe absorber thin films and improve optoelectronic properties by suppressing potential defects, causing short-circuit current (Jsc) loss. In this study, the structural, compositional, and morphological characteristics of CZTSSe and CZCTSSe thin films were investigated using X-ray diffraction (XRD), X-ray fluorescence spectrometer (XRF), and Field-emission scanning electron microscopy (FE-SEM), respectively. The FE-SEM images revealed that the grain size improved with increasing Cd2+ alloying in the CZTSSe thin films. Moreover, there was a slight decrease in small grain distribution as well as voids near the CZTSSe/Mo interface after Cd2+ alloying. The solar cells prepared using the most promising CZTSSe absorber thin films with Cd2+ alloying (8 min. 30 sec.) exhibited a power conversion efficiency (PCE) of 9.33 %, Jsc of 34.0 mA/cm2, and fill factor (FF) of 62.7 %, respectively.

Korean tuna purse seine fishery in the Western and Central Pacific Ocean (WCPO) began to operate in earnest in the early 1980s. Since then, the total catch has shown an increasing trend and the target species are skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacare) and bigeye tuna (Thunnus obesus). Based on the operational data of Korean tuna purse seine fishery from 2016 to 2020, the catch rates of target species (skipjack and yellowfin tunas) were analyzed by operation time for set types (free school and FAD sets). In the case of the free school sets, they were usually made from sunrise to sunset, and the catch rate was high before and after sunrise for skipjack tuna and before sunset for yellowfin tuna. On the other hand, for the FAD sets, more than 90% of them were made just before sunrise, and there were few operations during the daytime. The purpose of this study is to examine whether there are differences in the catch rate of skipjack and yellowfin tunas by operation time and by school type for Korean tuna purse seine fishery in the WCPO, which could be helpful in understanding its fishing characteristics and providing useful information for developing the stock indices of the target species.

This study aimed to evaluate the germination characteristics, -glucan and antioxidant contents, and antioxidant activity of naked oat according to germination temperature (20, 25, and 30oC) and time (24, 48, and 72 h). Sprout length was highest at 25oC, and the rotten degree was increased as the germination temperature and time increased. The -glucan content of naked oat increased after 24 h of germination at all temperatures and then decreased by 72 h of germination. Total polyphenol content, flavonoid content, and antioxidant activity increased as the germination temperature and time increased.

The purpose of this study was to investigate the Maillard reaction–related physicochemical properties of three maize varieties (Kwangpyeongok, Sinhwangok2ho and Gangdaok) after roasting them for different times (0, 15, 25, 40, and 55 minutes). The Maillard reaction is a non-enzymatic browning reaction involving reducing sugars and amino compounds. The content of reducing sugar, the causative agent of the Maillard reaction, decreased as roasting time increased. Gangdaok showed the lowest reducing sugar content of 1.04 mg/g after 55 minutes of roasting. In the elapsed roasting time, chromaticity ‘L’ and ‘b’ values decreased. At 55 minutes of roasting, wherein the Maillard reaction occurred most actively, Gangdaok showed the lowest ‘L’ value of 56.37 and the highest ‘a’ value of 7.60. Gangdaok had superior conditions for inducing the Maillard reaction compared to other varieties, and it is consider that 'flint–type', an endosperm characteristic, may have been the influencing agent. This study detected a total of 52 types of volatile aroma compounds (VACs), of which 28 were produced after roasting. Of the total VACs detected, 2-Formyl-5-methylfuran and 2-Furancarboxaldehyde accounted for 43.8~45.5% and have been confirmed to be the major VACs present in roasted maize. Most of the correlations between the Maillard reaction–related characteristics showed high correlation coefficients.

시간영역반사계(TDR)는 케이블의 물리적 결함을 검사하는 기법이며 누수 탐지 분야로의 응용영역을 확대하고 있다. 본 연구는 시간영역반사계 기법을 활용하여 선박 기관실 해수 배관의 누설 감지용 케이블형 센서를 개발하였다. 케이블 센서의 형상은 꼬임형상과 흡습부재를 이용하여 제작하였으며 개발된 센서의 누수 감지 여부와 위치 탐지 가능성을 확인하였다. 개발된 센서는 실제 배관 시험 장치 에 부착하여 평가하였으며 해수 누설에 따른 다양한 TDR 신호를 취득하였다. 센서는 꼬임횟수, 피복 두께를 변수로 하여 제작하였으며 TDR 신호에 미치는 효과를 분석하였다. 실험 결과, 꼬임형 센서는 평행한 띠 형상의 센서에 비해 평활한 신호 취득이 가능하였으며 최적 꼬임 횟수는 단위길이 당 10회 이상인 것으로 나타났다. 절연 피복두께의 경우 적정 민감도 확보가 가능한 절연 피복부재의 두께는 도선 직경의 80%~120%로 확인되었다. 누수 위치 추정을 위해 회귀분석 실시 결과, 결정계수는 0.9998로 실제 누설 위치와 높은 상관관계를 나타 내었다. 결과적으로 제안된 TDR 기반의 누수 감지용 꼬임형 센서는 해수 배관 시스템의 누수 감시 센서로의 충분한 적용성을 확인하였다.

This study is a plan on the way to strengthen the survival ability by increasing the use time of air respirator by applying emergency breathing method in the situation where firefighter has to wait for RIT (Rapid Intervention Teams) because it is impossible to escape by himself or emergency escape during isolation during field activities. The research procedure first drew problems by conducting a survey on fire fighters under the Seoul Fire and Disaster Headquarters, and conducted an experiment to compare normal breathing and emergency breathing with 20 members of the Seoul 119 Special Rescue Team, and suggested emergency breathing method and training process modeling that can be applied to each field situation based on the data obtained. The experiment was conducted over 9 weeks, and it was divided into three categories: field activity situation, movement (emergency escape assumption) situation, and place (assume waiting for RIT). In the field activity situation experiment, it was confirmed that the application of skip breathing method was appropriate and the use time of air respirator increased about 1.6 ~ 1.9 times. In the moving situation or the in-situ situation, wheel breathing method was appropriate and the use time of air respirator increased about 1.6 ~ 2.4 times. However, when conducting intense activities in the field activity situation, it is recommended to use it limitedly because it is difficult to apply the emergency breathing method. If emergency breathing is not clearly learned in the body, it is difficult to use in the field, so I think systematic and continuous training is necessary. This study suggests that the application of emergency breathing method is effective enough to strengthen the survival ability of firefighters in the field.

Markov envelope as a theoretical solution of the parabolic wave equation with Markov approximation for the von Kármán type random medium is studied and approximated with the convolution of two probability density functions (pdf) of normal and gamma distributions considering the previous studies on the applications of Radiative Transfer Theory (RTT) and the analysis results of earthquake records. Through the approximation with gamma pdf, the constant shape parameter of 2 was determined regardless of the source distance ro. This finding means that the scattering process has the property of an inhomogeneous single-scattering Poisson process, unlike the previous studies, which resulted in a homogeneous multiple-scattering Poisson process. Approximated Markov envelope can be treated as the normalized mean square (MS) envelope for ground acceleration because of the flat source Fourier spectrum. Based on such characteristics, the path duration is estimated from the approximated MS envelope and compared to the empirical formula derived by Boore and Thompson. The results clearly show that the path duration increases proportionately to ro 1/2-ro 2, and the peak value of the RMS envelope is attenuated by exp (-0.0033ro), excluding the geometrical attenuation. The attenuation slope for ro≤100 km is quite similar to that of effective attenuation for shallow crustal earthquakes, and it may be difficult to distinguish the contribution of intrinsic attenuation from effective attenuation. Slowly varying dispersive delay, also called the medium effect, represented by regular pdf, governs the path duration for the source distance shorter than 100 km. Moreover, the diffraction term, also called the distance effect because of scattering, fully controls the path duration beyond the source distance of 300 km and has a steep gradient compared to the medium effect. Source distance 100-300 km is a transition range of the path duration governing effect from random medium to distance. This means that the scattering may not be the prime cause of peak attenuation and envelope broadening for the source distance of less than 200 km. Furthermore, it is also shown that normal distribution is appropriate for the probability distribution of phase difference, as asserted in the previous studies.