• Journal of Korean Society of Steel Construction
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• v.16 no.1 s.68
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• pp.73-79
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• 2004

Tuned Mass Damper (TMD) was applied to control the vibration of an offshore structure due to ocean waves. The errors caused by the linearization of the fluid-structure interaction effect and the phenomena when using the linearized equation of motion in TMD design were analyzed. To determine the performance of TMD in controlling vibration, both regular waves with varying periods and irregular waves with different significant wave heights were used. When the offshore structure received regular waves with a period similar to the first natural period of structure. TMD performed well in terms of response reduction. Such was not the case for the other periods. however, In the case of irregular waves, TMD triggered the reduction of structural response for waves with relatively small significant wave height. For irregular waves with relatively big significant wave height, however, TMD did not show any control effect. Therefore, TMD is useful in reducing offshore structural vibration due to ambient waves, thereby helping secure fatigue life.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.314-327
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• 1997

A 2-dimensional soil water flow model was developed to describe the migration of soil moisture in drip-irrigated root zone employing cylindrical coordinate system. Several natural phenomena were incorporated into the model such as transpiration, various types of evaporation, and ponding due to the increase in irrigation rate. Model was solved numerically by finite difference method. The model was verified in several ways leading to the conclusion that it can describe the soil moisture migration in drip-irrigated root zone fairly well. From sensitivity analysis, vertical migration of soil moisture was found to move faster than the horizontal one, which indicates the vertical location just under the dripping point are adequate for measuring points of soil moisture. The pot shape of soil moisture in irrigated zone was proved to be caused by evaporation at the soil surface. Also, it was found that the hydraulic conductivity has greatly influential to the soil moisture migration, and that the soil moisture continues to migrate vertically after irrigation stops.

• Journal of Conservation Science
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• v.8 no.1 s.11
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• pp.1-9
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• 1999

The present aspect of the Seoggulam is the result of natural weathering of the rocks and influences by mankind. The rocks constituting the Seoggulam is granodiorite of medium and coarse grains which show brown to dark brown weathered surface resulted mainly from chemical weathering of feldspars. It also shows partly milky white or black colors due to influences by weathering products of cement used in the concrete dome and cracks. There are cracks and crack zones with very small cracks which may be formed by strong weathering and influences of shocks during operations of reconstitution and repair. However, for the better conservation, it must be considered to maintain the balances of temperature and moisture, especially relative moisture in places within the room, structural stability, and the influences of vibration made up by some reasons.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.4
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• pp.125-132
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• 2012

Urea-SCR system, which converts nitrogen oxides to nitrogen and water in the presence of a reducing agent, usually AdBlue urea solution, is known as one of the powerful NOx reduction systems for mobile as well as stationary applications. For its consistent and reliable operation in mobile applications, such various problems as transient injection, ammonia slip, and freezing in cold weather have to be resolved. In this work, therefore, numerical study on three-dimensional unsteady heating problems were analyzed to understand the melting and heat transfer characteristics such as urea liquid volume fraction, temperature profiles and generated natural convection behavior in urea solution by using the commercial software Fluent 6.3. After validating by comparing numerical and experimental data with pure gallium melting phenomena, numerical experiment for urea melting is conducted with three different coolant heating models named CH1, 2, and 3, respectively. Finally, it can be found that the CH3 model, in which more coolant is concentrated on the lower part of the urea tank, has relatively better melting capability than others in terms of urea quantity of $1{\ell}$ for start-up schedule.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.1
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• pp.63-72
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• 2015

The low and intermediate-level radioactive waste generated in Korea is disposed of at Wolsong Disposal Facility. For the safety of a disposal facility, it must be assessed by considering some abnormal scenarios including human intrusion as well as those by natural phenomena. The human intrusion scenario is a scenario that an incognizant man of the disposal facility will be occurred by the drilling. In this paper, the well usage scenario was classified into the human intrusion event as the probability of the well drilling is very low during the man's lifecycle and then was assessed by using conservative assumptions. This scenario was assessed using the dilution factor of contaminants released from a disposal facility and then it was introduced the applied methodology in this study. The assessed scenario using this methodology is satisfied the regulatory limits.

• The Journal of Information Systems
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• v.10 no.1
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• pp.27-50
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• 2001

The purpose of this study was to examine some of the most important factors for the development of information systems with today's fast-paced, ever-changing, and exciting information system environment. Especially, it was focused to investigate current information technology related to develop information systems, to find some important problems during the development process, and to suggest solutions for the problems. Case research methodology was used because a natural setting was needed and a focus was on contemporary events for this study. Similarly, research phenomena was not supported by a strong theoretical base. The case was the development of an integrated information systems in a specific university. Multiple-case designs were desirable, but single-case study was used because of limitations of site selection. Multiple data collection methods were employed in this study such as documentation, interviews, and direct observation. Some major problems were found during the system development. First, the schedule to complete a project was delayed over six months. Second, the system did not ensure to align organizational goals and information systems goals based on BPR (Business Process Reengineering). Third, there was a difficulty in evaluating request for proposal (RPR) returns and choosing a vendor. Finally, information technology is changing too fast. So, it was very difficult to get the transparency of new technology The study has suggested a few solutions: top management support, matching If planning with business planning, complete project plan and control, user participation, and training Finally, joint application development (JAD) is strongly recommended, which is a workshop that unites management, IT specialists, and knowledge workers to define and specify the logical requirements and technical alternatives for a proposed system.

• Child Health Nursing Research
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• v.8 no.1
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• pp.77-85
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• 2002

Recently in Korea, the adolescents' sexual problems including sexual violence have increased, and those phenomena have escalated to be one of the major social issues. This study was conducted to identify the variables related to the sexual harassments of the Korean adolescents. The variables to which the subjects belong were gender, school grade, religion, extracurricular activity, amount of pocket money, school performance traffic mean to school, ownership of PC, internet contact frequency and place, contact to pornography, heterosexual friend, drinking, and smoking. The period of survey was from July 2000 to Dec. 2000. The subjects were 475 middle and high-schoolers in Busan and Kyung-Nam. The instrument to measure sexual harassments of the subjects was questionnaire. That was gained by modifying the three patterns(physical, verbal and visual) in the manual provide by the Ministry of Labor(1999). The degree of sexual harassments was measured by 4-point Likert scale. The collected data was analyzed with t-test and ANOVA by SPSS win(10.0). The findings were as follows ;1. The variables related to the physical harassment were gender, age, pocket money, perceived school performance, traffic means, contact to pornography, having heterosexual friend, experience of drinking and smoking.2. The variables related to the visual harassments were gender, age, perceived school performance, traffic mean, internet contact, contact to pornography, having heterosexual friend, experience of drinking & smoking.3. The variables related to the verbal harassments were gender, age, pocket money, perceived school performance, traffic mean, internet contact, contact to pornography, having heterosexual friend, and experience of drinking & smoking.

• Transactions of the Korean hydrogen and new energy society
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• v.7 no.2
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• pp.121-128
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• 1996

A direct cooling equipment for hydrogen liquefaction has been developed and tested. A direct cooling equipment consists of a liquefaction vessel, a radiation shield, a cryostat and a GM refrigerator. The cool-down and warm-up characteristics of the liquefaction apparatus have been investigated in detail. It is found that the hydrogen starts to be liquefied in the liquefaction vessel after 45 minutes of cool-down. The cool-down and warm-up tests of helium gas are also performed. The cool-down and warm-up characteristics of helium gas are found to be very different from those of hydrogen gas, since helium is not liquefied under the present operating conditions. When the liquefaction vessel is evacuated, natural convection phenomena of charged gas in liquefaction vessel can be removed. It is seen that the cool-down time of liquefaction vessel is substantially increased in vacuum environment.

• Journal of The Korean Association For Science Education
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• v.19 no.2
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• pp.204-216
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• 1999

A value can be placed on the integrated science curriculum in terms of producing an insight into solving the routine problem. From such a point of view, the comprehensive concepts which explain the extensive natural phenomena were defined as the integrated themes in this study, and the contents of the integrated science curriculum were developed, as the understanding of the contents focused on the integrated theme enables us to be productive and have an insight. Through analyzing teaching materials, programs and curriculums in relation to the integrated science, five concepts of system, interaction, harmony and balance, structure and function, and circulation were established as the integrated themes, and the nature of each integrated theme was examined. Next, in accordance with the integrated theme, the content of the integrated science curriculum,which are deeper in aspect of the integration level than that of the current science of middle school, were developed. The content of the integrated science curriculum which was proposed in this study is of great significance. in that they provide new perspectives related to our current science curriculum.

• Journal of Radiation Protection and Research
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• v.27 no.1
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• pp.59-66
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• 2002

The role of experiments in science education is essential for understanding the natural phenomena and principle related to a subject. Therefore, the remote control experiment via Internet is one of key solution for distance learners in science education. The remote experiments ate also necessary for the time-consuming experiment which takes several days, collaborative experiment between distance learners, expensive laboratory equipment which is not usually available to students, experimental procedure which is dangerous, etc. In this study, we have developed a general method for a remote control laboratory system using internet and interlace techniques. It is possible for students to learn the nuclear physics to control the real instruments and conduct physics experimentation with internet techniques. We proposed the remote control radiation measurement system as a sample application. This system could be useful for the monitoring near a nuclear power plants in order to improve the environment data credibility to the public.