• 한국도로학회논문집
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• 제9권4호
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• pp.11-20
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• 2007

본 논문에서는 포장가속시험기를 이용하여 아스팔트 안정처리층의 피로모형을 개발하여 기존의 실내실험결과와의 상관관계를 분석하였다. 아스팔트 안정처리층의 피로모형은 Miner(1945)의 누적파손(Cumulative Damage)가설을 적용하였다. 포장가속시험에 사용된 아스팔트 안정처리층은 골재최대입경 25mm(BB-3)의 재료를 사용하였다. 포장가속시험결과 피로모형의 변수인 포장하부의 최대인장응력은 하중재하회수가 증가할수록 증가하는 것을 알 수 있었으며 포장층의 탄성계수는 점차 작아지는 것을 알 수 있었다. 아스팔트 피로모형의 기본식 $N_f=k_1(\frac{1}{\epsilon})^{k_2}$에서 변형률계를 통하여 얻은 인장변형률을 통하여 $k_1=1.29{\times}10^{-6}$, $k_2=3.02$의 값을 도출하였으며, 같은 인장변형률에서의 피로수명은 실내실험을 통한 모형보다 크게 나타났다. 또한, 비파괴실험인 FWD를 이용하여 포장의 잔존수명을 추정하는 논리를 개발하였다.

• Journal of Yeungnam Medical Science
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• 제12권2호
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• pp.331-338
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• 1995

18마리 가토의 양측 대뇌반구에 laserthemia후 발생하는 조직학적 변화와 온도변화에 따른 변성의 측정결과는 아래와 같다. 주된 조직학적 변화는 chromatin 응축, myelin 응축, 적혈구 탈색, nuclear waving, nuclear palisading과 세포괴사 등이었다. 온도 변화에 따른 변성의 정도는 $44.5^{\circ}C$이상에서 현저하였으며, 비교치 설명후 그 범위도 약 5배(1.25 mm)정도의 변화를 보였다. Laserthermia에 의한 세포괴사는 $47.5^{\circ}C$이상에서부터 현저하게 보였다. 뇌의 심부병소의 정위적 수술시 온도설정 및 병소치료 범위의 예상이 가능하다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.115-121
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• 2008

A core engine for pre-cooled turbojet engines is designed and its component performances are examined both by CFD analyses and experiments. The engine is designed for a flight demonstration of precooled turbojet engine cycle. The engine uses gas hydrogen as fuel. The external boundary including measurement devices is set within $23cm{\times}23cm$ of rectangular cross section, in order to install the engine downstream of the air intake. The rotation speed is 80000 rpm at design point. Mixed flow compressor is selected to attain high pressure ratio and small diameter by single stage. Reverse type main combustor is selected to reduce the engine diameter and the rotating shaft length. The temperature at main combustor is determined by the temperature limit of non-cooled turbine. High loading turbine is designed to attain high pressure ratio by single stage. The firing test of the core engine is conducted using components of small pre-cooled turbojet engine. Gas hydrogen is injected into the main burner and hot gas is generated to drive the turbine. Air flow rate of the compressor can be modulated by a variable geometry exhaust nozzle, which is connected downstream of the core engine. As a result, 75% rotation speed is attained without hazardous vibration and heat damage. Aerodynamic performances of both compressor and turbine are obtained and evaluated independently.

• 아태비즈니스연구
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• 제12권1호
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• pp.209-223
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• 2021

Purpose - The purpose of this study was to investigate the relationship between Korea agricultural productions and Greenhouse Gas (GHG) emissions based on Environmental Kuznets Curve (EKC) hypothesis. Design/methodology/approach - This study utilized time series data of economic growth, greenhouse gas, agricultural productions, trade dependency, and energy usages. In order to econometric procedure of EKC hypothesis, this study utilized unit root test and cointegration test to check staionarity of each variable and also adopted Vector Error Correction Model (VECM) and Ordinary Least Square (OLS) to analyze the short and long run relationships. Findings - In the short run, greenhouse gas emissions resulting from economic growth show an inverse U-shape relationship, and an increase in agricultural production and energy consumption led to increase in greenhouse gas emission. In the long run, total GHG emissions and CO2 emissions show an N-shaped relationship with economic growth, and an increase in agricultural production has resulted in a decrease in total GHG and CO2 emissions. However, methane (CH4) and nitrous oxide (N2O) emissions showed an inverse U-shape relationship with economic growth, which indicated the environment and production process of agricultural production. Research implications or Originality - Korea agricultural production has different effects on the GHG emission sources, and in particular, methane (CH4) and nitrous oxide (N2O) emissions show to increase as the agricultural production expansions, so policy or technological development in related sector is required. Especially, in the context of the 2030 GHG reduction road-map, if GHG-related reduction technologies or policies are spread, national GHG emission reduction targets can be achieved and this is possible to predict the decline in production in the sector and damage to the related industries.

• 한국화재소방학회논문지
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• 제33권1호
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• pp.99-104
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• 2019

신속한 화재 진압을 목표로 가스계 소화 시스템에서 소화약제는 일반적으로 섭씨 $21^{\circ}C$에서 약 28 MPa의 고압으로 저장되며, 방출시 감압밸브와 오리피스를 지나면서 약 8 MPa의 압력으로 방출한다. 때문에 방출시 약 140 dB 이상의 소음이 발생하게 되는데, 이로 인하여 hard disk drive (HDD)와 같은 전자 부품들이 손상되기도 한다. 따라서 소음문제는 가스계 소화 시스템에 있어서 중요한 문제점으로 대두되고 있다. 소음문제 해결방안으로는 일반적으로 흡음재를 부착하여 소음을 저감시키는 방안이 있으며, 본 연구에서는 흡음재의 두께를 설계 변수로 선정하여 유동소음을 저감하는 방안을 고찰하였다. 관측점에서의 소음도와 노즐내부 유로에 나타나는 유동특성은 상용 코드인 ANSYS CFX ver. 18.1을 이용하여 수치적으로 계산하여 분석하였다.

• 산경연구논집
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• 제12권7호
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• pp.27-39
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• 2021

Purpose: The researchers reviewed the previous studies on the psychological anxiety and economic damage during the recent COVID-19 pandemic to understand the satisfaction, awareness and attitude of the residents in Jeju, Korea. Research design, data and methodology: 215 samples based on self-reported survey were collected for path analysis focused on controlling variables in demographic characteristics in PLS-SEM using Smart PLS 3.0. Results: The researchers found the Satisfaction with COVID-19 Prevention Measures and the Awareness of Tourism Crisis affect Attitude toward Tourism of the residents with the explanatory power (R² = 0.209). Age was found to be the only significant controlling variable in this model for the Awareness of Tourism Crisis to Attitude toward Tourism. Conclusions: The attitude toward tourism is influenced by the level of satisfaction of the prevention service for COVID-19 as well as the awareness of the crisis. Residents have different level of the tourism crisis awareness by the status of their economic activities while there is no differences in all age groups for satisfaction in the quarantine service. The study suggests that the importance of the public health service should be preferentially concerned for residents to have stable economic activities where the tourism is the major industry.

• 융합경영연구
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• 제8권2호
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• pp.13-17
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• 2020

Purpose: In modern corporate management, the establishment of a crisis management system that minimizes damage through measures used to respond to corporate crises is no longer an option. The importance of corporate reputation and brand asset management in modern enterprise management cannot be overemphasized and negative events that might arise from a number of different causes can cause brand crises. Research design, data and methodology: More than half of the questionnaire respondents were female (252 or 53%). More than a fourth of the respondents were aged 20 (122 or 26%) and the number of married participants was 196 (41%). Of the participants, 32% (153) had graduated from college. Only 18% (87) were employees and the monthly household income was 121. In this study, we conducted factor analysis in order to extract the variables that may enhance the explanation capability of each variable. For the method of factor extraction, an Eigen value of at least 1 was used as was factor loading. An analysis was performed using the Cronbach's alpha coefficient to verify the reliability of the measurement scale. Results: First, the analysis of the impact of the social responsibility activities on brand image revealed that the social, economic, philanthropic, ethical, and environmental responsibility activities significantly affected brand image, but legal responsibility activities were not statistically significant. Second, the analysis of the impact of brand image on loyalty showed that brand image had a significant impact on loyalty. Third, the analysis of the impact of social responsibility activities on loyalty showed that they had a significant impact on loyalty. Conclusions: The pro-social enterprise image is not only a brand asset that can be shared, but also a heavy proposition followed by a corresponding social responsibility, it will have to practice transparent corporate management based on clear principles through the establishment of various systems and the implementation of a strict code of conduct within the enterprise.

• 한국환경보건학회지
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• 제47권4호
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• pp.310-319
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• 2021

Background: Humidifier disinfectant exposure is an ongoing issue, and there is still considerable related controversy. Various approaches are needed to secure scientific evidence on the extent of the victims' damages and for the determination of appropriate compensation. Objectives: The purpose of this study was to assess the association between humidifier disinfectant (HD) use and academic achievement in Korean children. Methods: This study used data from the 8th Panel Study on Korean Children in 2015. For the final study, 1,598 cases were used. T-tests and multiple linear regression analyses were conducted to determine whether the use of humidifier disinfectant is a factor that affects academic ability. Results: Children in groups using humidifier disinfectant showed statistically significantly lower scores in all areas of language, including reading, speaking and writing, and statistically lower scores in all areas of mathematics, including counting, addition and subtraction. In the multiple regression analysis results, which control for the effects of various demographic/social variables, the use of humidifier disinfectants showed statistically significant beta coefficients (β: -0.357, p<0.001), negatively affecting children's language ability. As for the 'math' variable, which was created by combining counting, addition, and subtraction scores, the use of humidifier disinfectants as independent variables also showed statistically significant beta coefficients (β: -0.200, p<0.001), negatively affecting children's math ability. Conclusions: The results of the study showed that depending on whether or not humidifier disinfectants were used, there are differences in children's language abilities, such as reading, speaking, and writing, as well as in their mathematical abilities, such as counting, adding, and subtracting numbers. These findings are thought to serve as a scientific basis for extending the perspective from health effects to more diverse areas of demographic and social impact related to humidifier disinfectant damage and compensation.

• 한국구조물진단유지관리공학회 논문집
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• 제26권5호
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• pp.151-160
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• 2022

최근 폭발사고의 빈도수가 증가함에 따라 주요 구조부재의 손상을 저감시킬 수 있는 방호 구조물 설계에 대한 관심이 높아지고 있다. 그러나, 방호 구조물의 방호성능에 대한 국내 연구는 아직 미진한 실정이며, 아직 설계 가이드라인도 충분히 갖추어지지 못한 실정이다. 따라서, 본 연구에서는 FRP 시트 보강유무를 변수로 하여 RC 방호벽에 대한 해석적 연구를 수행하였다. 해석은 LS-DYNA 프로그램을 활용하여 수행되었으며, 해석을 통해 RC 방호벽과 FRP 시트로 보강된 RC 방호벽의 변위-시간이력곡선, 압력-충격량 도표, 취약도 곡선을 도출하였다. FRP 시트 보강방법은 RC 방호벽의 방호성능을 향상시키는데 매우 효율적인 것으로 나타났다. 또한, 폭발하중의 크기가 클수록 RC 방호벽에 대한 FRP 시트의 보강효과는 높아지는 것으로 나타났다.

• Composites Research
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• 제34권2호
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• pp.101-107
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• 2021

복합재료를 활용하여 설계되는 구조물은 각 부품들의 조립, 체결부를 갖게 된다. 이러한 연결 또는 조인트는 구조에서 잠재적으로 취약 부분이 될 수 있다. 복합재료 볼트 조인트의 파손모드는 구조 안전성을 위해 베어링 파손모드로 설계된다. 베어링 파손모드로 파괴되는 복합재료 볼트 조인트의 하중-변위 관계는 초기 파손 발생 후 비선형 거동을 보이며, 점진적인 파손을 보인다. 이러한 비선형적이고 점진적인 복합재료 볼트 조인트의 파손거동을 정확히 예측하기 위해 본 연구에서는 기존의 파손해석 모델에서 전단 손상변수 계산 과정에 수정을 수행하였다. 수정된 파손해석 모델을 이용하여 복합재료 볼트 조인트의 베어링 응력-베어링 변형률 결과를 예측하였으며, 기존 수정되지 않은 해석모델과 비교를 통해 수정된 모델의 유효성을 입증하였다.