• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.1
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• pp.1-14
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• 2021

Onions are a representative produce that requires supply-demand control measures due to large fluctuations in production and price by growing season. Accurate forecasts of crop production can improve the effectiveness of such measures. However, it is challenging to obtain accurate estimates of crop productivity for onions because they are mainly grown on the open fields. The objective of this study was to perform the empirical analysis of the relationship between factors for crop growth and meteorological conditions, which can support the development of models to predict crop growth and production. The growth survey data were collected from open fields. The survey data included the weight of above ground organs as well as that of the bulbs. The estimates of meteorological data were also compiled for the given fields. Correlation analysis between these factors was performed. The random forest was also used to compare the importance of the meteorological factors by the growth stage. Our results indicated that insolation in early March had a positive effect on the growth of the above-ground. There was a negative correlation between precipitation and the growth of the above-ground at the end of March although it has been suggested that drought can deter the growth of onion. The negative effects of precipitation and daylight hours on the growth of the above-ground and under-ground were significant during the harvest period. These meteorological factors identified by growth stage can be used to develop models for onion growth and production forecast.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.361-370
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• 2021

The purpose of this study was to identify the factors influencing college life stress and life satisfaction of nursing students. The subjects included nursing students from some select areas. The research was conducted in November and December 2020. The data of a total of 227 nursing students were analyzed using descriptive statistics, t-test, ANOVA, Pearson correlations, and stepwise multiple regression analysis. The findings show that college life stress, economic conditions, and interpersonal relationships had significant effects on life satisfaction of the nursing students with an explanatory power of 27.1%. The study examined life satisfaction based on general characteristics and found variations according to college life satisfaction (F=5.88, p=.003), grades (F=7.07, p=.001), interpersonal relationships (F=8.80, p=.000), and economic conditions (F=10.53, p=.000). There was a statistically significant negative correlation between their college life stress and life satisfaction (r=-.436, p<.001). To summarize, these findings raise a need to provide nursing students with a strategy to address economic issues by reducing their academic stress through an improved educational environment, help them keep positive interpersonal relationships through effective communication, and offer them active information such as counseling so that they can achieve life satisfaction.

• Journal of Korea Entertainment Industry Association
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• v.14 no.2
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• pp.195-203
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• 2020

Purpose: This study was a descriptive study to investigate on the effect of calling, self-efficacy, workplace bullying on retention intention among nurses in small and medium-sized hospitals. Methods: The research subjects were 224 nurses selected through convenient sampling from among those who have worked six months or longer in seven small and medium-sized hospitals located in G City. The data were collected using a structured questionnaire from July 17 to 30, 2018. The data was analyzed by descriptive statics, a t-test, ANOVA, Scheffé test, Pearson's correlation coefficient, and a stepwise multiple regression using SPSS/WIN 22.0 program. As a measuring tool, Calling was the Calling & Vocational Questionnaire (CVQ) developed by Dik, Eldrige and Steger (2008). Self-efficacy was developed by Sherer et al. (1982) and modified by Jeong Ae-soon (2007). Workplace bullying was developed by Einarsen, Raknes and Matthiesen (1994) in the Norwegian Negative Behavioral Experience Questionnaire (NAQ), and by Nam Woong et al. (2010). The retention intention was to use NRI (Nurses' Retention Index) developed by Cowin (2002) as a tool for Kim Min-jung (2006). Results: Factors affecting nurses' retention were analyzed. The analysis showed that retention intention was positively affected by self-efficacy (β=.24, p<.001), sense of calling (β=.23, p<.001) and annual wage (β=.21, p=.001) and negatively affected by workplace bullying (β=-.16, p=.008) on a statistically significant level, with an explanatory power of 28.6%.

• Journal of the Korean Regional Science Association
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• v.38 no.4
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• pp.3-17
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• 2022

This study aims to empirically analyze the impacts of the topographic characteristics of residential areas and the characteristics of land use and transportation on average trip distance of the senior citizens in Busan Metropolitan city. Multiple regression is conducted to accomplish the purpose of this study, and the conclusions and policy implications of the analysis are as follows. First, the average and standard deviation of the residential areas are significantly related to average trip distance of the senior citizens. Thus, urban transportation policies need to take account of the topographic characteristics of the residential areas. Second, average distance from the nearest subway station and density of bus stops have positive and negative association respectively. Mobility improvement polices for senior citizens should consider urban spatial structure and different approach processes to transportation facilities by modes. Third, mobility and residential environment improvement policies for senior citizens should take into account different sociodemographic characteristics by locations. This shows that the mobility convenience policy for senior citizens is more necessary than any other policy for administrative dong, where traffic access is relatively low and the single senior citizen population is concentrated.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.5
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• pp.189-196
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• 2022

Skyline query is a scheme for exploring objects that are suitable for user preferences based on multiple attributes of objects. Existing skyline queries return search results as batch processing, but the need for real-time search results has increased with the advent of interactive apps or mobile environments. Online algorithm for Skyline improves the return speed of objects to explore preferred objects in real time. However, the object navigation process requires unnecessary navigation time due to repeated comparative operations. This paper proposes a Pre-processing Online Algorithm for Skyline Query (POA) to eliminate unnecessary search time in Online Algorithm exploration techniques and provide the results of skyline queries in real time. Proposed techniques use the concept of range-limiting to existing Online Algorithm to perform pretreatment and then eliminate repetitive rediscovering regions first. POAs showed improvement in standard distributions, bias distributions, positive correlations, and negative correlations of discrete data sets compared to Online Algorithm. The POAs used in this paper improve navigation performance by minimizing comparison targets for Online Algorithm, which will be a new criterion for rapid service to users in the face of increasing use of mobile devices.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.1-7
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• 2021

The purpose of this study was to analyze the effect of household loan share on bank management soundness. The results of the empirical analysis are summarized as follows. First, as a result of estimating coefficient of the mortgage loan ratio shows a significant negative relationship with the BIS equity capital ratio of banks. In addition, it was found that the mortgage loan ratio had a significant positive (+) effect on Eunhae's BIS and equity capital ratio after the financial crisis. Second, as a result of the estimation coefficient of the mortgage ratio showed a significant positive (+) relationship with the NPL of the bank and below. In addition, it is estimated that the bank's secured loan ratio changed significantly before and after the financial crisis in the effect of banks' NPL and substandard-and-below loans. It is expected to make implication to financial policy and banking regulation and supervision. We believe that more efforts should be made to increase the soundness of household loans in preparation for risk factors that may arise from exogenous factors such as changes in the international financial environment and falling property prices.

• The Journal of the Acoustical Society of Korea
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• v.41 no.3
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• pp.302-311
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• 2022

Sound barrier walls are one of the most effective alternatives for reducing environmental noise on roads and railways in the city center. The insertion loss of the sound barrier against road traffic noise is the sum of the sound transmission loss, sound absorption loss, and sound energy reduction due to the diffraction attenuation of the sound barrier. The sound transmission loss of the sound barrier is one of the important factors that determine the insertion loss of the sound barrier and is a basic indicator that determines the performance of the sound barrier. Nevertheless, there is not a separate standard in Korea for measuring the acoustic transmission loss of sound barrier panels. There are only a few conditions in KS F 4770 series that stipulates on the general material of sound barrier panels. This thesis examines the necessity of the acoustic transmission loss measurement and evaluation standards of sound barrier walls, and seeks a measurement method in a free sound field (anechoic chamber) sound receiving room considering the characteristics of sound barrier walls installed in external spaces, unlike indoor building materials. In addition, a single number evaluation method using a reference spectrum was proposed so that the sound insulation effect according to various installation places such as roadside or railroad side can be easily displayed.

• Journal of Korea Port Economic Association
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• v.38 no.4
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• pp.107-118
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• 2022

In this study, daily data from January 2002 to June 2022 were used to investigate the relationship between risk-return relationship and market fear, uncertainty, stock market, and maritime freight index for the crude oil market. For this study, the time varying EGARCH-M model was applied to the risk-return relationship, and the wavelet consistency model was used to analyze the relationship between market fear, uncertainty, stock market, and maritime freight index. The analysis results of this study are as follows. First, according to the results of the time-varying risk-return relationship, the crude oil market was found to be related to high returns and high risks. Second, the results of correlation and Granger causality test, it was found that there was a weak correlation between the risk-return relationship and VIX, EPU, S&P500, and BDI. In addition, it was found that there was no two-way causal relationship in the risk-return relationship with EPU and S&P500, but VIX and BDI were found to affect the risk-return relationship. Third, looking at the results of wavelet coherence, it was found that the degree of the risk-return relationship and the relationship between VIX, EPU, S&P500, and BDI was time-varying. In particular, it was found that the relationship between each other was high before and after the crisis period (financial crisis, COVID-19). And it was found to be highly associated with organs. In addition, the risk-return relationship was found to have a positive relationship with VIX and EPU, and a negative relationship with S&P500 and BDI. Therefore, market participants should be well aware of economic environmental changes when making decisions.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.41-41
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• 2022

홍수는 단기간의 사상이다. 평상시 유량은 일단위로 연속유량이라 한다. 홍수해석은 사상 모형을 이용하고, 물 이용의 용수계획에서는 연속 모형에 의한다. 평상시 유량을 홍수처럼 10분, 30분, 60분 단위로 해석할 수 있으면 여러 가지로 편리하다. 홍수기에는 홍수와 이수를 동시에 분석할 수 있는 이점이 있다. 평상시에는 수문자료가 생성되는 기본단위가 10분, 60분이기 때문에 이와 일치하여 유량을 해석할 수 있는 이점이 있다. 특히 저수지에서는 운영자료가 저수율 자료만 관리되고 있는 현실을 감안하면, 연속 홍수모의의 필요성은 매우 높다. 다목적댐도 그 편의성은 말로 형용할 수 없는 수준이다. 홍수모의는 첨두유량도 중요하고, 전체 누적유량도 중요하다. 여기서는 당초 일 단위로 개발된 ONE 모형으로 연속 홍수모의의 가능성을 타진했다. 모형의 검증은 홍수사상 마다 훨씬 긴 장기간의 댐의 유입량, 저수량 오차로 실시했다. 유입량이 누적되면 저수량이 되기 때문에 저수량을 비교하면 확실한 검증 방법이 된다. 유역면적 930.0km², 총저수량 8억1,500만m³인 용담댐과 유역면적 218.80km², 유효저수량 3,498만m³인 탑정지를 대상으로 60단위의 장기간 연속 홍수모의 결과를 제시한다. 첫째, 용담댐에 대해 2020년 3월1일부터 6월30일까지 연속유입량을 모의한 결과(ONE모형 매개변수 α=3.18), 면적우량은 최대 12.5mm, 총 371.2mm(3억4,522만m³)였고, 유입량은 최대 1,363.0m³/s, 총 1억8,326만m³로 유출률 53.1%였다, 관측 유입량은 최대 766.1m³/s, 총 2억9,152만m³로 유출률 84.4%로 나타났다. 관측 유입량이 높은 것으로 평가했는데 그 이유는 산정된 유입량이 넓은 수면적에서 오는 음유입량이 발생하는데 이를 0으로 처리하고, 음의 누적 값이 전체유량에 더해지는 계산의 한계에서 비롯한다. 이는 현실적 제한이며, 개선이 필요하다. 댐 수위로 검증한 결과는 관측수위는 EL.257.97~262.92m, 평균 EL.260.40m, 모의수위는 EL.257.22~262.88m, 평균 EL.260.02m로 나타났고, RMSE는 0.174, NSE는 0.959, R²는 0.968로 만족한 결과를 얻었다. 둘째, 탑정지에 대해 2020년 3월1일부터 6월30일까지 연속유입량을 모의한 결과(ONE모형 매개변수 α=3.18), 면적우량은 최대 18.5mm, 총 311.4mm(6,813만m³)였고, 유입량은 최대 187.8m³/s, 총 3,691만m³로 유출률 54.2%였다. 저수지 수위로 검증한 결과 관측수위는 EL.26.55~29.79m, 평균 EL.29.01m, 모의수위는 EL.26.16~29.92m, 평균 EL.29.07m로 나타났고, RMSE는 0.563, NSE는 0.877, R²는 0.943로 만족한 결과를 얻었다. 정리하면 2020년 4개월의 장기간 용담댐과 탑정지에 대한 1시간 간격의 연속 홍수모의의 결과는 그 활용 가능성이 충분하다고 말하고 있다. 이 결과로부터 평상시 댐과 저수지의 실시간 운영자료 검증 및 생산체제의 수문관측업무에 활용 가능한 것으로 평가했다.

• Journal of Internet Computing and Services
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• v.24 no.6
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• pp.171-180
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• 2023

Hydrogen energy technology is gaining importance in the era of the Fourth Industrial Revolution, offering military advantages when applied to military vehicles due to its characteristics such as reduced greenhouse gas emissions, noise, and low vibration. Korea's military has initiated the Army Tiger 4.0 plan, focusing on hydrogen application, downsizing, and AI-based smart features. The Ministry of National Defense plans to collaborate with the Ministry of Environment to expand hydrogen charging stations nationwide, anticipating increased deployment of military hydrogen vehicles. However, considering the Jet Fire and VCE(Vapor Cloud Explosion) nature of hydrogen, ensuring safety during installation is crucial. Current military guidelines specify a minimum safety distance of 2m from adjacent buildings for charging stations. Scientific methods have been employed to quantitatively assess the accident damage range of hydrogen, proposing a minimum safety distance beyond the affected area.