• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.3
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• pp.191-200
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• 2016

The ventilation effect of a ventilation system, which is classified as the forced ventilation and natural ventilation, is predominantly dependent on the combination of air supply and discharge. Perhaps the simplest ventilation is merely supplying the air as it is. However, to improve the indoor working environment during the summer, an air supply that is cooled to some extent has been widely adopted. Recently, a cooling method utilizing the vaporization of water was introduced. In this study, the performance of an evaporation-type air supply unit that was produced by Japan K-company and was installed in a shoe-manufacturing plant in Busan was investigated. The purpose of the experiment was to measure how much the supplied air could be cooled. From this experimental study, we confirmed that the evaporation-type air supply system is efficient, capable of improving the working environment during the summer while minimizing the energy cost.

• Applied Chemistry for Engineering
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• v.18 no.2
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• pp.126-129
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• 2007

In order to ruduce traffic-jam, it is requested to extend road. As a result, the construction of tunnels is inevitable considering our mountatinous topography. In tunnel construction work, major contamination materials occur from rock drilling, blasting rock, rock transporting, and short-creat. After rock blasting, a very high concentration of particles over $5000{\mu}g/m^3$ is maintained for 4 h when air is supplied by pans, by which the construction work has to be delayed at least 30 min. Although dry dust collectors are used, the effective operation time span is limited to 3 h. In this work, the behavior of particles in air and use of particle removal instruments are investigated. As a result, it was important to compare efficiencies of dry and hydro dust collectors.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.515-517
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• 2008

현재 가동 중인 원자적발전소 계측제어설비의 전원공급기를 살펴보면 인버터 또는 별도의 교류를 입력전원으로 사용한다. 직류 전원공급기들은 설비의 중요도예 따라 이중화로 구성된 설비도 있고 그렇지 않은 기기나 설비도 있다. 이중화로 구성된 전원공급기라 해도 교류 입력전원이 동일하다면 교류 입력이 상실될 때 이중화로 구성된 직류전원도 상실되어 관련계통의 가동이 정지된다. 이러한 문제점을 해결하기 위해서는 각기 다른 교류입력전원으로 동작되는 이중화전원공급기로 구성되는 것이 가장 바람직하다. 본 연구개발의 목적은 두 종의 설비에 소요되는 3종의 직류전원 공급기를 원자력 안정성등급으로 국산화하는 연구이다. 기존 제품들은 3종 모두 리니어 방식의 제품이지만, 방사선감시 계통 현장제어기의 5V로직 전원공급기와 공정제어계통 전원공급자는 전력변환효율이 높고 소형, 정량화가 가능한 SMPS(Switched Mode Power Supply) 방식으로 개발하였다. 방사선감시계통 현장제어기의 PCA(Printed Circuit Assembly) 저전압공급기는 다양한 종류의 출력전압과 저 전류형이므로 안정성 면에서 동일한 형식의 리니어 방식으로 개발하였으며 3종류 모두 출력용량을 20% 이상 향상시켰다. 또한, 논문을 통해 SMPS 방식의 전원공급기의 핵심 부품인 Control Module을 Hybrid IC형으로 자체 설계하여 성능이 우수한 제품을 지속적으로 생산할 수 있는 기틀을 마련하고자 한다.

• Journal of Engineering Education Research
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• v.6 no.1
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• pp.56-64
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• 2003

In this paper, we designed and implemented a client/server distributed environment and developed a web-based virtual laboratory system for electronic circuits. Since our virtual laboratory system is implemented to describe the on-campus laboratory, the learners can obtain similar experimental data through it. The proposed virtual laboratory system is composed of four important components : Principle Classroom, Virtual Experiment Classroom, Evaluation Classroom and Overall Management System. Through our virtual laboratory, the learners will be capable of learning the concepts and theories related to electronic circuit experiments and how to operate the experimental equipments such as multimeters, function generators, digital oscilloscopes and DC power supplies. Also, every experimental activity occurred in our virtual laboratory is recorded on database and printed out on the preliminary report form. All of these can be achieved by the aid of the Management System. The database connectivity on the web is made by PHP and the virtual labol'atory environment is set up slightly differently for each learner. Finally, we have obtained several affirmative effects such as reducing the total experimental hours and the damage rate for experimental equipments and increasing learning efficiencies as well as faculty productivity.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.6
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• pp.626-632
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• 2015

The International Maritime Organization (IMO) has adopted several regulations for the prevention of air pollution from ships. In addition, there is a requirement for shipping liners to reduce greenhouse gas emissions. Accordingly, we need to take measurements to ensure that the steps taken are both efficient and environmentally friendly. It has been determined that the application of the Miller cycle in diesel engines has the effect of both reducing the amount of NOx and improving thermal efficiency. However, this method requires a considerably larger charge air pressure. Therefore, we consider a two-stage turbo-charging system, which not only results in a high charging pressure, but also improves the part load performance with an exhaust-gas bypass system or the application of the Miller cycle. Because of complications associated with the two-stage turbo-charging system, it is complex and difficult to realize a design that optimizes matching between diesel engine and turbo-chargers. Accordingly, it is necessary to perform a quantitative analysis to determine the effects and optimal conditions of these different systems in the early stage of system design. In this paper, we develop a simulation program to model these systems, and we verify that the results of this program are reliable. Further, we discuss methods that can be employed to improve its efficiency.

• KDI Journal of Economic Policy
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• v.18 no.2
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• pp.185-209
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• 1996

북한(北韓)의 경제개발전략(經濟開發戰略)의 제특징(諸特徵)은 저렴한 농산물가격(農産物價格)에 의한 농업부분(農業部分)에서의 잉여(剩餘), 저임금(低賃金)에 의한 도시노동자(都市勞動者)들로부터의 잉여(剩餘)를 가지고 경제발전(經濟發展)을 이룩하는 것이라 요약할 수 있다. 농민(農民), 도시노동자(都市勞動者) 양측(兩測)을 희생시키면서 유지되어 온 이러한 성장구조(成長構造)는 원래 같으면 저농산물가격(低農産物價格)${\rightarrow}$저임금(低賃金)${\rightarrow}$축적자금확대(蓄積資金擴大)${\rightarrow}$재투자(再投資)${\rightarrow}$생산량증가(生産量增加)${\rightarrow}$소비수준 (消費水準) 증가(增加)로 점진적으로 발전해야만 하는 것이다. 하지만 이러한 성장전략(成長戰略)은 처음부터 철저히 부정되어 왔다. 먼저 농촌부분(農村部分)부터 보면 농촌협동조합(農村協同組合)에서의 소유제도(所有制度), 분배제도(分配制度)의 문제(問題)로 인해 농민(農民)의 근로의욕(勤勞意欲)이 크게 상실되었고 그 결과(結果) 농업생산(農業生産)은 저하되었다. 한편 도시부분(都市部分)에서는 인민(人民)들의 저소비(低消費)의 결과(結果)로 축적된 자금(資金)이 군사부분(軍事部分)에 집중적으로 투자됨으로 인해 그 투자효과(投資效果)가 제 구실을 못하게 되었다. 뿐만 아니라 자급자족지향형(自給自足指向型)의 중공업화(重工業化)는 중공업(重工業)과 관련산업(關聯産業) 상호간(相互間)의 수요(需要)만을 충족시켜 왔다. 그 외에 기업(企業)이 국가(國家)의 지령(指令)에 의해서만 움직이는 국영기업관리체제(國營企業管理體制)의 비효율성(非效率性)도 지금의 북한경제(北韓經濟)를 침체(沈滯)의 늪에서 헤어나지 못하게 하는 주요(主要)한 요인(要因)으로 작용했다. 농업생산(農業生産)의 정체(停滯), 중공업(重工業)을 위한 중공업정책(重工業政策)이라고 하는 왜곡된 투자구조(投資構造), 기업관리체제(企業管理體制)의 비효율성(非效率性)은 북한(北韓)의 계획경제순환구조(計劃經濟循環構造)를 기본(基本)부터 뒤흔들기 시작하면서, 급기야 1980년대 후반부터는 순환구조(循環構造) 그 자체(自體)를 마비시키는 사태(事態)로까지 발전했다. 순환구조(循環構造)의 마비(痲痺)라고 하는 심각한 경제난(經濟難)을 타개하기 위해 북한(北韓)은 나진(羅津) 선봉(先鋒) 자유경제무역지대(自由經濟貿易地帶)를 설치(設置)하고 새로운 자금축적원(資金蓄積源)으로서 외국인직접투자(外國人直接投資)를 유치하는 개방정책(開放政策)을 추진하여 왔다. 하지만 북한(北韓)의 경제(經濟) 순환구조(循環構造)의 마비(痲痺)를 풀 수 있는 근본적(根本的)인 해법(解法)은 어디까지나 그 발단(發端)인 농촌(農村)의 경제체제개혁(經濟體制改革), 농(農) 경공업(輕工業)을 위한 중공업(重工業), 국영기업(國營企業)의 개혁(改革) 등을 과감히 실시하는 것이다. 왜냐하면 해외직접투자(海外直接投資)라는 새로운 자금축적원(資金蓄積源)은 어디까지나 지금의 악순환구조(惡循環構造)를 임시적(臨時的)으로 정지시켜 주는 보완적(補完的)인 조치(措置)에 불과하기 때문이다.

• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.11-18
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• 2024

If flammable liquid leaks, vapor evaporated from the pool can cause poisoning or suffocation to workers, leading to secondary accidents such as fires and explosions. To prevent such damage, ventilation facilities shall be installed when designing indoor workplaces. At this time, the behavior varies depending on the characteristics of the leaked chemical, so it is necessary to select a suitable vent location according to the material. Therefore, 3D CFD simulations were introduced to derive optimal vent position and ventilation efficiency was quantitatively evaluated by vent position. At this time, assuming a situation in which flammable liquids leak at indoor workplaces to form pools, the concentration of vapor evaporated from pools was compared to derive the optimal vent position. As a result of research on toluene with high vapor density, ventilation efficiency was confirmed to be the highest at the upper supply-lower exhaust, and it is judged that introducing it can achieve about 3.7 times ventilation effect at the same maintenance cost. Through this study, it is expected that the workplace will be able to secure workers' safety by applying simulation results and installing ventilation ports.

• Korean Security Journal
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• no.17
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• pp.301-316
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• 2008

The occurrence of complicating, multilateral social condition demands the strategy for facing many social state and consolidating public security against criminal loss. The lacking ability of local police for preventing crime can't satisfy the demand of security and can't get rid of fear of crime. At last, it brings a distrust of public confidence and became a factor of serious social crisis. We have problems - not only making an alternative plan for preventing crime, but also introducing CPTED(Crime Prevention Through Environmental Design) by environmental design, to expect crime prevention and to select systemic crime prevention system and the most suitable model. And we have a goal - to recognize the importance of guard activity for local crime, analyse public safety activity in community & focusing guard activity as a strategy for them, apply CPTED in police and private security company as a local crime prevention & setting effective model, and, make it as an index for preventing & dealing with intellectual, brutal crime. The rapid growth in the guarding-activity field lighten the burden of police for crime-prevention. But the misjudgement of some people blocks it to be settled institutionally. It needs to reconsider what is the effective crime-prevention method, at this point of time when the all parts of a nation changing into unlimited competitive, private self-control system.

• The Journal of the Korea Contents Association
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• v.12 no.6
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• pp.518-529
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• 2012

Integration of Europe was started when European Union Treaty was concluded at Maastricht for the first time on December, 1991. Europe which may be called as a cradle of modern national state has realized a single Europe not only in the socio-economic integration field but also in the political field. Under this background, it is considered that life-long education policy for developing a new integrated growth engine of EU requires educational response that may get ready for socio-economic environmental transformation more than anything else. In particular, this policy is faced with an important task of having to achieve harmony of efficiency through diversity and mutual coordination in pursuing cooperation and integrated development of life-long education field. However, notwithstanding their efforts, since 2008, some countries of EU were faced with economic crisis due to economic recession and this situation starts to drive the whole Europe even to the point of their financial crisis at last. This crisis is currently shaking socio-economic integration of EU. This study intends to observe a status of establishing life-long education system and promoting a policy for socio-economic integration of EU and to analyze as to what kind of relevance adult participation rate of life-long learning among the countries belonged to EU has with per capita income and to explore as whether socio-economic integration among member countries could be sustained based on problems of integrative life-long education system under the economic crisis of EU. In addition, through this study, an implication required for presenting a new paradigm conversion, policy establishment and development direction for the life-long education of our country is intended to be deduced.

• Journal of Navigation and Port Research
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• v.44 no.3
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• pp.244-252
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• 2020

The 2008 global financial crisis was triggered by the Lehman Brothers crisis caused by the sub-prime mortgage crisis in the United States This crisis has had an impact on the globe's dry bulk shipping market by reducing dry bulk cargo volume. An oversupply of dry bulk carriers caused a serious recession in the globe's dry-bulk shipping industry and shipbuilding industry. In this situation, the Korean dry-bulk shipping companies were victims of the quagmire of a long recession since the global financial crisis and could not overcome this crisis. This condition forced them into severe financial risk Thus, it caused many shipping companies to file for bankruptcy. In this study, we classified Korean ocean-going dry-bulk shipping companies into two groups, that is, the solvent group and the insolvent group. We also separated the research period before and after the 2008 global financial crisis. Then we investigated the differences in the major financial ratios of the two groups by t-test and found that some financial ratios such as profitability ratios and growth ratios showed the difference between the two groups with statistical significance. The significance of this study is as follow. First, the shipping company management is also crucial for the systematic management of financial strength and business strategy, it is crucial to manage cargo which a high profitable freight. Second, the shipping company should be managed as a company with continued growth through efficient operation and management of ships.