• 대한조선학회논문집
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• 제51권4호
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• pp.334-341
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• 2014

Due to the rise of international oil prices, with the continued increase of vessel operating costs, profitability has gradually deteriorated in the some case of South Korea ferry shipping. Therefore, it is necessary to improve the resistance performance of passenger ship. Goose neck bulb can be one of the methods to improve the resistance performance of passenger ship. Goose neck bulb has been applied to passenger ships operated in Europe and large cruise line. But there is no application example in the passenger ship to be operated on a regular basis in the sea near Korea. It is needed to provide reference data that can be applied efficiently goose neck bulb on the medium-sized passenger ships. This study, intended for the medium-sized passenger ship operated short international routes, presents the design of the hull form that goose neck bulb has been applied. And the resistance performance of the designed hull confirmed by numerical simulation. The numerical simulation is performed while changing the local shape of the goose neck depending on the bulb parameters. This study finds bulb parameters and their range that can affect the resistance performance. Thus, it is possible to provide a foundation to develop the optimal design technique and regression analysis on the resistance performance and goose neck bulb.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2018년도 추계학술대회
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• pp.24-24
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• 2018

Degraded plantation forests are increasing because of unfavorable forestry conditions prevailing in Japan, including falling timber prices, increasing operational costs, and aging and declining forestry workforce. To remedy this situation, appropriate management strategy is required. This study introduces the challenges of Odai Town, Mie Prefecture that employed a new management strategy by evaluating site suitability for conifer forests and that proposes a new forest management regime of planting deciduous trees in unsuitable sites. The site suitability for conifer forests was evaluated from two aspects: the natural site conditions and the relationship among site conditions, growth, and damage by Anaglyptus subfasciatus Pic. in Cryptomeria japonica D. Don and Chamaecyparis obtusa Sieb. Et Zucc. forests. By analyzing the relationship among site conditions, growth, and insect damage based on field data obtained in plantation forests, growth evaluation and insect damage evaluation maps were developed. Based on the natural forest investigation, natural site condition maps for C. japonica and C. obtusa were established. Furthermore, by integrating these evaluation maps with the forest road maps showing the accessibility to the forest, the forest management regime for the whole plantation area of Odai Town was established. The forest management regime map indicates the sites suitable for forestry: suitable for long-rotation, short-rotation, and potential sites for short-rotation. The sites unsuitable for forestry were considered to be more suitable for broadleaved forests. Clear-cutting was conducted in a small area and different seral stage saplings (approximately 20 deciduous tree species) suitable to the site conditions were planted in an area of $80-120m^2$ protected by deer-fences. This might establish a forest composed of many species with a multilayer vertical forest structure in a short period. The planted saplings were distributed neither randomly nor uniformly to reflect the natural distribution of trees in the forest. A challenge to develop new products using the deciduous trees has started, such as wood chips for preparing smoked food, essential oil, and deodorizer. As these challenges have just begun, their effects on enhancing sustainable resource management are still being monitored. Even with the challenges, this regime can be of high value as a management strategy to remedy the situation of expansion of degraded forests in Japan.

• 대한인간공학회지
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• 제33권3호
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• pp.203-214
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• 2014

Objective: This study aims to examine the psychological effects of pilots caused by the environmental differences between actual and simulated flights by measuring biochemical stress level and subjective stress level. Background: Currently, the flight system of the air force suffers from several problems including a limited training area, increase of complex and tangled missions and rise in oil prices. In order to overcome these problems an L-V-C (Live, Virtual, Constructive) training system has been proposed as a solution. However, to establish the effective L-V-C training system, it is required to figure out the characteristics of each system first. Also we have to solve the problems which could occur when these systems are connected together. Method: In order to measure the biochemical stress level of pilots, we investigated the differences in cortisol responses after actual and simulated flight training separately. Meanwhile, we conducted the questionnaire survey of about 40 pilots to identify the subjective stress level of pilots. Results: There was significant difference in cortisol level between actual and simulated flight tasks. However, we found that there was no significant difference in pilots' feelings about two flight tasks. Conclusion: The results from this study can be used as basis for the further research on not only how to decrease linkage errors of the L system and the V system but also how to make the L-V training system more practical. Application: The results of the analysis might help to develop the Live-Virtual-Constructive (LVC) pilot training system.

• 수산경영론집
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• 제43권3호
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• pp.75-87
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• 2012

Today, the Korean fisheries is undergoing significant hardships, both domestically and internationally. While declining amount of catch, ascending international oil prices and others pose a compelling challenge to the fishing sector, the ever strengthening influence of international institutions related to fisheries and international trade organizations also compel to bring about myriad of changes in the realm of fishery products. Against the backdrop, this study attempted to examine the fisheries catch, aquaculture, service, processing fields in terms of its rippling effect and of how the industry has been changed by analyzing the past and present through an input-output analysis. As for research methods, 168 items of the input-output tables in 2000, 2005, 2009, and 2010 were integrated to form and classify 32 sectors (28 basic sectors + catch, aquaculture, fishery service, processed fishery products) so as to generate production inducement coefficient, sensitivity coefficient, and impact coefficient. The analysis results revealed that : though the linkage effect of fishery industry was not very sizable, the impact coefficient of the processed fishery products was high; the consumption and investment coefficient sector among production inducement coefficient was on an upturn trend ; the export coefficient was tended to decline. In the future research, it is necessary to carry out a study based on the integration of detailed classification (404 sector) and a study and analysis of fishery industry by different regions through the inter-regional input-output tables. The fishery industry is one of the crucial industries in Korea. The fishery industry is not only important in its own right but also significant as it exerts influence over other industries. Therefore, it is required that there should be more investment and supports for the development of the fishery industry, and pay efforts to ensure that the investment and development could lead to mutual growth for both the fishery and other various industries.

• 융합보안논문지
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• 제16권6_2호
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• pp.43-51
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• 2016

1980년대의 민간경비는 1976년 용역경비업법이 제정되면서 마련된 제도적인 틀 속에서 성장하는 시기였다. 1980년 민간경비의 발전을 가져온 동인은 우선 저 달러가치, 저 국제금리, 저 원유가격이라는 국제경제환경에 힘입어 국내 경제가 고도성장을 하고 무역수지 흑자를 가져오면서 호황을 누리게 된 것이다. 아울러 전자산업 고도화계획에 따라 추진하던 반도체, 컴퓨터 및 통신기기분야가 육성되었다는 점이다. 이러한 경제발전에 따라 다양한 서울국제무역박람회, '86 아시안게임, '88 서울올림픽 등의 국제행사와 국내행사가 개최됨에 따라 민간경비가 참여하여 성공적인 경비업무를 수행함으로서 민간경비에 대한 인식제고와 확산의 계기가 되었다. 또 1980년대에는 일본 세콤을 비롯하여 외국기업의 한국투자 또는 한국의 기술도입이 민간경비산업에도 많은 변화를 가져온 것이다. 그동안 인적 경비를 중심으로 해오던 민간경비가 기계경비 또는 시스템경비가 보완되는 기계경비시대를 가져왔다는 점이다. 본 연구의 목적은 1980년대의 민간경비를 둘러싼 사회적 환경을 분석하고 민간경비에 발전적인 계기가 되는 중요한 요소들을 체계적으로 분석하는 것이다.

• 한국ITS학회 논문지
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• 제8권2호
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• pp.108-117
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• 2009

현재 우리나라에서는 자전거 이용 활성화를 통해 교통문제를 해소하며, 고유가 시대의 에너지 절약 효과를 얻고자 하고 있다. 그러나, 자전거 인프라 시설의 부족 및 기존 자전거 도로 및 관련시설의 안전성과 연계성이 보장되지 않는 등의 이유로 자전거 이용이 불편한 실정이다. 따라서 본 연구에서는 안전성, 편의성, 연계성 등의 다양한 영향요소들을 고려하여 이용자 중심의 자전거 서비스 수준(BLOS: Bicyclist Level of Service) 모형을 개발함으로써 기존 자전거 도로 및 시설의 서비스 수준을 정의하고 개선하는데 기여하고자 하였다. 또한, 순차적 의미를 주는 선택, 선호, 강도 등에 관련된 연구에 적합한 순서형 프로빗 모형(Ordered Probit Model)을 적용함으로써, 자전거 이용자의 만족도를 고려한 자전거 서비스 수준 평가 기준을 제시하고자 한다. 본 연구에서 개발한 모형을 통해 자전거 서비스 수준 평가를 수행함으로써 기존의 자전거 도로 및 시설을 이용자 관점에 맞도록 개선할 수 있으며, 이러한 과정을 통해 자전거 시설 이용 증진을 도모할 수 있겠다. 또한, 자전거 도로망 계획, 자전거 도로 설계, 개선 효과에 따른 자전거 도로 및 시설의 투자 우선순위 결정 등에 활용될 것으로 기대된다.

• 산업경영시스템학회지
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• 제39권1호
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• pp.31-36
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• 2016

Recently, Live-Virtual-Constructive (L-V-C) integrate training system has proposed as a solution for the problems such as limitation of training areas, increase of mission complexity, rise in oil prices. In order to integrate each training system into the one effectively, we should solve the issue about stress of pilots by the environmental differences between Live and Virtual simulation which could be occurred when each system is connected together. Although it was already examined in previous study that the psychological effects on pilots was occurred by the environmental differences between actual and simulated flights, the study did not include what the causal factors affecting psychological effects are. The aim of this study is to examine which environmental factors that cause pilots' psychological effects. This study analyzed the biochemical stress hormone, cortisol to measure the pilots' psychological effects and cortisol was measured using Enzyme-linked immunoassay (EIA). A total of 40 pilots participated in the experiment to compare the differences in pilots' cortisol response among live simulation, virtual simulation, and the virtual simulation applying three environmental factors (gravity force, noise, and equipment) respectively. As a result, there were significant differences in cortisol level when applied the gravity force and equipment factors to the virtual simulation, while there was no significant difference in the case of the noise factor. The results from this study can be used as a basis for the future research on how to make L-V system by providing minimum linkage errors and design the virtual simulator that can reduce the differences in the pilots' psychological effects.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.248-257
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• 2020

This study presents an initial design for a novel system consisting in a coupled nuclear reactor and a phase change material-based thermal energy storage (TES) component, which acts as a buffer and regulator of heat transfer between the primary and secondary loops. The goal of this concept is to enhance the capacity factor of nuclear power plants (NPPs) in the case of high integration of renewable energy sources into the electric grid. Hence, this system could support in elevating the economics of NPPs in current competitive markets, especially with subsidized solar and wind energy sources, and relatively low oil and gas prices. Furthermore, utilizing a prismatic-core advanced high temperature reactor (PAHTR) cooled by a molten salt with a high melting point, have the potential in increasing the system efficiency due to its high operating temperature, and providing the baseline requirements for coupling other process heat applications. The present research studies the neutronics and thermal hydraulics (TH) of the PAHTR as well as TH calculations for the TES which consists of 300 blocks with a total heat storage capacity of 150 MWd. SERPENT Monte Carlo and MCNP5 codes carried out the neutronics analysis of the PAHTR which is sized to have a 5-year refueling cycle and rated power of 300 MW_th. The PAHTR has 10 metric tons of heavy metal with 19.75 wt% enriched UO₂ TRISO fuel, a hot clean excess reactivity and shutdown margin of $33.70 and -$115.68; respectively, negative temperature feedback coefficients, and an axial flux peaking factor of 1.68. Star-CCM + code predicted the correct convective heat transfer coefficient variations for both the reactor and the storage. TH analysis results show that the flow in the primary loop (in the reactor and TES) remains in the developing mixed convection regime while it reaches a fully developed flow in the secondary loop.

• 수산해양기술연구
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• 제50권1호
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• pp.12-20
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• 2014

The objective of this paper is to aid in basic directions for the countermeasure against marine accidents by using the statistical data of Jeju Coast Guard from 1983 to 2012. Marine accidents of about 600~1,000 vessels was reported in all the waters around South Korea from 2000 to 2008. From 2009, these accidents increased rapidly and reached 1,600~2,000 vessels. Although marine accidents of longline fishing vessels did not show a big change prior to 1993, the number have increased steadily until 2007. This is considered a tendency that appears when longline vessels, using the Port of Sungsanpo as a base and operating in fishing grounds in the East China Sea, are converted to long-term fishing from short-term fishing for reasons such as cost reduction due to the sudden rise of oil prices and the performance improvement of the fishing vessels. The number of vessels in marine accidents decreased gradually from 1999 to 2002 and for nearly 7 years from 2002 to 2008, the annual average of marine accidents stayed at 97 vessels. This is seemed to be the result of a change in the policy of either the central or local government and largely associated with changes in the way of statistical processing. This tendency is resulted in lower number of the accidents due to careless navigation which can be viewed as a human error than the number of marine accidents due to poor maintenance as a cause of mechanical failure in the same period. The increase rate in the marine accidents of Jeju Island-based fishing vessels is greater than that of other area-based fishing vessels among the fishing vessels operating in coastal and near sea around Jeju Island each year.

• 한국ITS학회 논문지
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• 제7권2호
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• pp.1-12
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• 2008

최근 극심함 교통혼잡 및 유류비 상승으로 인해 대중교통(특히 버스)의 역할이 더욱 크게 부각되고 있으나, 일부 황금노선을 제외한 대부분의 버스노선이 지속적인 이용수요감소, 수입감소, 경영수지악화, 서비스질 저하, 이용자감소의 악순환을 끊기 위해 버스의 공공성 강화의 한 방편인 준공영제(관리는 공공, 운영은 민영)를 도입하였으나, 당초 민간의 효율성을 제고하고자 했던 의도와는 다르게 운수회사의 자발적인 운행관리가 이루어지지 않는 등 부작용을 해결하기 위한 공공부분의 운행관리가 매우 중요한 요소가 되었다. 본 연구에서는 준공영제 하에서, APTS 자료를 활용하여 민간 운수회사의 평가관리가 가능하고, 시민이 피부로 느낄 수 있는 버스신뢰성 제고를 위해 서울시에서 관리중인 운행관리항목의 종류와 분석방법론, 운행관리결과, 문제점 및 향후 대책에 대하여 고찰하였으며, 이러한 연구내용이 이미 준공영제를 도입하였거나, 도입을 준비하고 있는 타 시도의 운행관리정책에 기여할 수 있을 것이다.