• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.5
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• pp.431-439
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• 2013

A cooling system is adopted to control the thermal load from the avionic equipments in an aircraft for stable operation. In this study, an avionic cooling system was designed and manufactured by adopting a vapor compression cycle with a closed-loop air-circulation system to investigate the operating characteristics of an alternative refrigerant. The performance characteristics of a cooling system adopting R236fa as an alternative refrigerant were experimentally determined by varying the refrigerant charging amount, expansion valve opening, and compressor rotation speed. The experimental results were analyzed and compared with those of a cooling system adopting R124 as a refrigerant. The possibility of the adoption of R236fa as an alternative refrigerant was verified, and design solutions were suggested to improve the system efficiency.

• Korean Security Journal
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• no.50
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• pp.61-87
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• 2017

National Assembly is a constitutional institution that is required to first consult the will of the people and it should do its effort continuously so that security of citizens using parking lot would be enhanced at the same time while improving parking service in order to increase customer satisfaction of the people. Under this recognition, in this study, Doonchi parking lot of National Assembly under consigned management was first reviewed in a perspective of criminal prevention through environmental design(CPTED) and particularly, fence installation and reinforcement work for securing 'territoriality' and operation of all round shooting camera and installation of No-trespassing warning board at entrance were suggested. Second, it was recommended to change independent control system in which CCTV security system of National Assembly Doonchi parking lot is operated separately from National Assembly safety situation room and integrate it with National Assembly safety situation room(revised to double safety system) and performance of CCTV camera was made to be increased to over 2m. In addition, video recording mode was converted to NVR mode for application to IP camera in the future and in order to avoid dead zone of security monitoring area and based on site inspection result, addition 3 places of newly installing CCTV were indicated. Third, it was recommended to introduce parking fare billing and management system through unmanned equipment in parking lot management and operation.(specialized management of professional parking service provider was reviewed). By doing so, risk of cash handling by charging personnel was removed by reducing current 7 working personnel to 3 and particularly, by converting parking lot management mode being operated temporarily from 9 A.M. to 9 P.M. at present to 24 hours operation mode and providing more specialized parking service, citizens visiting National Assembly were provided with convenience and image of National Assembly was also enhanced. This study was carried out in parallel with various literature and case studies, including data from the Office of the Defense Protection in the National Assembly.

• Journal of the Korean Institute of Gas
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• v.5 no.2 s.14
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• pp.30-35
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• 2001

Presently, working gas pipelines are being subjected to the influence of construction vibration. Especially on subway and road construction, gas pipelines are being influenced to construction vibration caused by use of construction equipment, passage of a large-sized vehicle and blasting. Buried gas pipelines are subjected to the influence of vibration caused by blast in the vicinity of pipeline, exposed gas pipelines are subjected to the influence of vehicle vibration. Therefore, in the study, it is developed to vibration prediction program of gas pipeline by analyzing measured construction vibration. This program is able to predict vibration of gas pipeline according to field conditions by using the results of structural finite element analysis and empirical equation by reliability analysis. And, this program contains the database of construction vibration. Additionally, this program is able to compute estimated blast vibration equation using measured blast vibration data in the field and to form graph of allowable charging gunpowder per delayed-action with the change of blast velocity. Therefore, field workers are able to predict construction vibration around gas pipeline and estimate safety of gas pipeline.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.325-333
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• 2020

This study compares the rapidity and subjective convenience of T-AED and SC-AED for health care providers and the general public. Subjects were randomly allocated to T-AED (n=77) and SC-AED (n=79) groups. Each group conducted defibrillation, with subsequent measurement of the rapidity of defibrillation in peri-shock pause, pre-shock pause, hesitation pause, and post-shock pause. Defibrillation and chest compression delay times for both equipment were analyzed by t-test. On conclusion of the experiment, subjects answered a questionnaire on the subjective convenience of defibrillation, as measured for confidence, convenience, and clear decision. Comparisons of subjective convenience analyzed by t-test revealed significantly shortened peri-shock pause (11.22s), pre-shock pause (11.04s), and hesitation pause (2.15s) in the SC-AED group, as compared to the T-AED group (p<0.001). However, no significant differences were observed for post-shock pause values. Comparing subjective convenience, confidence (T-AED: 7.62±1.25VAS vs. SC-AED: 7.80±0.98VAS, p=0.358) was not significant, whereas convenience (T-AED: 7.05±1.36VAS vs. SC-AED: 8.95±0.89VAS, p<0.001) and clear decision (T-AED: 6.58±1.73VAS vs. SC-AED: 9.08±0.98VAS, p=0.001) showed statistically significant differences. Our results indicate that compared to T-AED, SC-AED has significantly shortened pauses. Moreover, it is more convenient for the user, and significantly aids in clear decisions.

• Explosives and Blasting
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• v.22 no.3
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• pp.57-64
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• 2004

There are two major types of underwater blasting at Korea, bridges and harbor construction work. Pier blasting for lay the foundation bridges construction is used dry excavation working (drilling and charging) after pump out water and then fire pump in water that is same as bench blasting. In contrast, underwater blasting for harbor construction and increase of harbor load depth is used to barge with digging equipment that is in oder to drilling on the surface and blasting work(charge, hook-up) under water. Thus, there are need to special concern such as charge method and hook-up method different from tunnel blasting work and bench blasting work. If do not use special concern breaks out dead pressure and mis fire because of there are so many difficult condition such as water pressure, obstruct field of vision. In this study underwater blasting at Busan Harbor Construction have consider with special concern that is plastic pipe charge method used to MegaMITE I and specialized buoy hook- up method make far initial system detonate on the surface used to TLD. The results is designed blast pattern charge per delay effect an inspection of verify between predict velocity and measure velocity. minimized break out mis fire consideration charge method, hook up method. According to result best underwater blasting design is 105mm drilling dia, MeGAMITE II, HiNLL Plus(non electric detonator).

• Journal of Energy Engineering
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• v.16 no.4
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• pp.202-214
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• 2007

The concept of HSA (Home Service Aggregator) is derived from performing the energy IT business efficiently as well as successfully launcing a new service based on BPL (Broadband over Power Line). The HSA business using a BPL can extend the field of energy industry and an give a chance to create a new demand by consumer-oriented services. This study focuses on the exact evaluation of HSA business using BPL, and reasonable trusty evaluation should be the first step to launch the HSA business. In this study, the categories of cost are comprised of equipment (mainly RSM and MGW) cost, instalation cost, and maintenance cost. AMR (Automatic Meter Reading), internet integration billing service, integration charging service, internet service, sorority service, and electricity safety are listed for benefit. In this study, the ROI of HSA business is 0.9594, which is less than 1. However, that value does not consider the electricity safety benefit which is classified as a social benefit. Therefore, the value can be above 1 if it includes social and private benefits.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.7
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• pp.523-529
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• 2011

This study has been performed to examine the influence of the size of particles on the stabilization in the aerobic stabilization equipment connected with MBT system. The biodegradable waste inside the reactor (60% of food waste, 25% of paper waste, 2% of wood waste and 5% of compost) has been charged in same composition. The degree of stabilization was compared and analyzed after charging with adjustment of particle size in 5 mm, 10 mm, 20 mm, 50 mm, 100 mm and state of no separation. The experiment revealed that highest temperature beyond $65^{\circ}C$ was shown in the particle size of less than 50 mm in change of temperature and the highest temperature was about $50^{\circ}C$ in reactor of 100 mm and no separation. The proportionality between generated quantity of $CO_2$ and particle size was not observed, even the highest in generated quantity was shown in over 100 mm. The weight changes based on wet and dry conditions in the reaction process showed the 30% and 46% of reduction in the smallest particle size of 5 mm and it showed the trend of the lower reduction rate at the bigger particle size. The water soluble $COD_{Cr}$ and TOC showed the reduction rate of 60% in reactor of particle size in 100 mm and no separation while the reduction rate comparing to the initial stage of reaction in the reactor of less than 50 mm was 80%. Such result derived the conclusion of acceleration in the decomposing stabilization of biodegradable material due to the decomposing rate of organic substance as the particle size of biodegradable waste gets smaller. It is concluded as necessary to react in adjustment under 50 mm of particle size as much as possible.

• Korean Security Journal
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• no.27
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• pp.129-159
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• 2011

Physical security has always been an extremely important facet within the security arena. A comprehensive security plan consists of three components of physical security, personal security and information security. These elements are interrelated and may exist in varying degrees defending on the type of enterprise or facility being protected. The physical security component of a comprehensive security program is usually composed of policies and procedures, personal, barriers, equipment and records. Human beings kept restless struggle to preserve their and tribal lives. However, humans in prehistoric ages did not learn how to build strong house and how to fortify their residence, so they relied on their protection to the nature and use caves as protection and refuge in cold days. Through the history of man, human has been establishing various protection methods to protect himself and his tribe's life and assets. Physical security methods are set in the base of these security methods. Those caves that primitive men resided was rounded with rock wall except entrance, so safety was guaranteed especially by protection for tribes in all directions. The Great Wall of China that is considered as the longest building in the history was built over one hundred years from about B.C. 400 to prevent the invasion of northern tribes, but this wall enhanced its protection function to small invasions only, and Mongolian army captured the most part of China across this wall by about 1200 A.D. European lords in the Middle Ages built a moat by digging around of castle or reinforced around of the castle by making bascule bridge, and provided these protections to the resident and received agricultural products cultivated. Edwin Holmes of USA in 20 centuries started to provide innovative electric alarm service to the development of the security industry in USA. This is the first of today's electrical security system, and with developments, the security system that combined various electrical security system to the relevant facilities takes charging most parts of today's security market. Like above, humankind established various protection methods to keep life in the beginning and its development continues. Today, modern people installed CCTV to the most facilities all over the country to cope with various social pathological phenomenon and to protect life and assets, so daily life of people are protected and observed. Most of these physical security systems are installed to guarantee our safety but we pay all expenses for these also. Therefore, establishing effective physical security system is very important and urgent problem. On this study, it is suggested methods of establishing effective physical security system by using system integration on the principle of security design about effective security system's effective establishing method of physical security system that is increasing rapidly by needs of modern society.