• Journal of the Korean Solar Energy Society
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• v.26 no.3
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• pp.17-24
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• 2006

최근에 에너지절약 차원에서 종래의 공조방식을 대신할 새로운 냉난방시스템 개발이 요구되고 있는데, 본 논문에서는 태양열 집열기를 이용하는 데시컨트 시스템 중 제습역할을 실질적으로 담당하는 제습기의 충진층 부분에서의 열 및 물질전달에 관한 일련의 해석 결과를 발표하고 있다. 제습과정에서 액체흡수제는 충진층에서 열 뿐만 아니라 물질전달을 수반하게 되는데, 이 결과 건물에 냉방 및 난방효과를 가져다 준다. 따라서 이 충진층의 최적 설계가시스템의 효율을 극대화하기 위해서는 무엇보다도 중요한데, 이를 위해서는 충진층에서의 열 및 물질전달 양상을 규명하여야 한다. 따라서 금번 실험에서는 공기와 액체흡수제와의 접촉면적을 넓히기 위해서 충진재로써 3cm(직경) ${\times}$ 3cm(높이)인 시판중인 플라스틱 재질을 사용하고, 실질적으로 40cm(너비)${\sim}$40cm(깊이)${\times}$40cm(높이)의 충진층을 직접 제작하여 실험을 행하였다. 그 결과, 공기측 열 및 물질전달 계수는 공기 온도와 밀접한 관계를 갖고 있으며, 또한 물질전달계수는 열전달계수와 같은 경향을 보이고 있음을 알 수 있었다.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.584-589
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• 2008

The in put system using the touch screen directly makes the input signals by the contact on the screen without the assistance of peripherals such as a pen or hands. These kinds of input systems using the flexible hands is maximizing suppleness and intuition of the input rather than those systems using a keyboard or a mouse which are moving a cursor or typing a word. However, using hands for an input may give rise to a mistake in control. And there are few interfaces utilizing the touch screen. Incorrectness and insufficiency of the interface are the weak point of the touch screen systems. In this paper, we propose the dial menu user interface for the mobile devices using touch screen for an efficient input. In this method, it consists of 2 states(Inactive states, Active states) and 4 actions(Rotation, Zoom in, and Zoom out, and Click). The intuitive control utilizing the suggested method overcomes the incorrect pointing, weak point of the touch screen system, and boosts the searching menu by utilizing the drag function of the touch screen.

• Journal of Radiation Protection and Research
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• v.37 no.4
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• pp.213-218
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• 2012

Alpha spectrometry has been typically used for determination of the uranium isotopes in soil. For a number of uranium analysis in soil samples, rapid sample digestion with limited quantities of mixed acid containing HF will give a contribution for effective management of uranium analysis. Microwave digestion system is evaluated for rapid sample digestion using reference uranium soil (IAEA-375 soil). For completion of 0.5 g of soil digestion by microwave, 3 ml of HF in a 10 ml of mixed acid is minimum requirement volume for completed soil digestion for 80 minutes. Microwave digestion is timely effective techniques for uranium measurement using alpha spectrometry compared to the other methods (open vessel digestion, closed vessel digestion) due to rapid sample digestion. In addition, it can be reduced the occurrence of hazardous substances by minimizing the amount of HF.

• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.122-128
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• 2008

We evaluated the relationship between the multiplication of heterotrophic microorganisms and physicochemical factors in the final discharged sewage water from J municipal waste water treatment plants. Dissolved organic carbon (DOC) was the most crucial factor influencing multiplication of heterotrophic plate counts (HPC) among the water quality variables selected. Degrading bacteria, such as proteolytic bacteria, lipholytic bacteria, starch degrading bacteria, cellulolytic bacteria, and pectinolytic bacteria, were monitored to understand the condition of nutrients in finished sewage effluent. The percentages of lipid and protein combined occupied 81% in finished sewage water. The multiplication of HPC showed the highest value in August. The formation of trihalomethane (THM) was low in the finished discharge water during chlorine disinfection, which was $71{\mu}/L$ (which was less than $100{\mu}/L$- the standard of drinking water quality) with 10 mg/L of chlorine during 15 min.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.2
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• pp.144-149
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• 2011

The lock-in thermography was employed to evaluate the integrity of railway bogies. Prior to the actual application on railway bogies, in order to assess the detectability of known flaws, the calibration reference panel was prepared with various dimensions of artificial flaws. The panel was composed of structural steel, which was the same material with actual bogies. Through lock-in thermography evaluation, the optimal frequency of heat source was determined for the best flaw detection. Based on the defects information, the actual defect assessments on railway bogie were conducted with different types of railway bogies, which were used for the current operation. In summary, the defect assessment results with thermography method showed a good agreement as compared with the conventional inspection techniques. Moreover, it was found that the novel infrared thermography technique could be an effective way for the inspection and the detection of surface defects on bogies since the infrared thermography method provided rapid and non-contact mode for the investigation of railway bogies.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.3
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• pp.341-348
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• 2007

The efficiency of powdered activated carbon (PAC) for removing taste and odor (T&O) in drinking water supplies is dependent on the contact time, quality of mixing, and the presence of competing compounds. All of these are strongly influenced by the stage in the treatment process at which the PAC is added. In conventional water treatment plants (WTPs), PAC is commonly added into the rapid mixing basin where chemicals such as coagulants, alkaline chemicals, and chlorine, are simultaneously applied. In order to prevent interference between PAC and other water treatment chemicals, alternative locations for addition of PAC, such as at transmission pipe in the water intake tower or into a separated PAC contactor, were investigated. Whatever the location, addition of PAC apart from other water treatment chemicals was more effective for geosmin removal than simultaneous addition. Among several combinations, the sequence 'chlorine-PAC-coagulant' produced the best result with respect to geosmin removal efficiency. Consequently, when PAC has to be applied to cope with T&O problems in conventional WTPs, it is very important to prevent interference with other water treatment chemicals, such as chlorine and coagulant. Adequate contact time should also be given for adsorption of the T&O compounds onto the PAC. To satisfy these conditions, installation of a separated PAC contactor would be the superior alternative if there is space available in the WTP. If necessary, PAC could be added at transmission pipe in the water intake tower and still provide some benefit for T&O treatment.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1224-1228
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• 2005

본 연구는 강우시 주로 발생되는 강우유출수에 의해 하천으로 직유입 되는 다량의 오염물질을 사전에 저감시키기 위하여 하천의 제방사면부와 둔치부를 형상화한 Pilot 규모의 수처리시스템에 관한 것이다. 본 Pilot Plant는 경희대학교 내 하수처리장 부근에 설치하였으며, 유입부, 사면수처리부, 평면수처리부, 유출부로 구성되며, 수처리조 내부에 다공성여재와 상부에는 식생을 조성하여 연속적으로 운영되는 시스템으로 설계되었다. 사면수처리부는 하천의 제방사면부를 형상화 한 것으로 2:1의 구배를 가지며, 15개의 육각형 모듈을 5개씩 3계열로 배치하여 여재의 처리효율 및 현장 적용성 검토를 실시할 수 있도록 배열하였다. 평면수처리부는 장방형의 접촉산화조로서 하부에 슬러지 침전 및 저류를 위한 hopper를 설치하여 슬러지의 원활한 수집 및 인발이 가능하도록 설계하였다. 또한, 역세를 위한 배관을 설치하여 여재에 부착된 슬러지의 양 조절이 가능하도록 하였다. 또한, 수처리시설물의 자연 친화성 확보 및 식생에 의한 수질개선 효과를 위해 수처리부 상부에 식생을 조성하였다. 본 Pilot Plant의 주요 오염물질의 제거기작은 수처리부 내부에 충진된 다공성 여재와 강우유출수 사이에 발생되는 침전, 여과, 흡착과 여재에 부착된 미생물에 의한 유기물 분해, 식생에 의한 영양물질 섭취 등으로 대별된다. 본 연구는 하천의 제방사면부와 둔치부를 형성화한 Pilot Plant에서 다양한 factor, 즉 유입수량과 농도, 다공성여재 형상 및 충진밀도 등에 따른 수질개선 효과를 각각 비교, 검토하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1302-1307
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• 2011

The Spiral coil is made considering primary, secondary side coil inductance, turn number, size, thickness, and shielding area with the litz wire-type in case of manufacturing a coil, and at this time, the semi-automation winding machine is used. When deciding on primary and secondary side coil specification and manufacturing a coil, the spiral coil of a specification varied in the various litz wire of a specification is required, and at this time, a difficulty is generated by the manufacture cost, period which during, and failure the manufacture is generated in the coil sample making. A difficulty is in the desired coil quality control of a specification. Since improving the rectifier of the secondary side in order to improve this kind of problem, the range of the coil design and the during the manufacture, various coil manufacture specifications can be comprehensively made.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.2
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• pp.207-212
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• 2016

High-frequency induction hardening (HFIH) is used in many industries and has a number of advantages, including reliability and repeatability. It is a non-contact method of providing energy-efficient heat in the minimum amount of time without using a flame. Recently, HFIH has been actively studied using the finite-element method (FEM), however, these studies only focused on the accuracy of the analysis. In this paper, we analyzed HFIH by using a variable frequency based on the conditions of the same shape and input power then comparing the analysis results to experimental results. The analysis and experimental results indicate that the hardening depths are approximately the same using the optimal frequency of 3kHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1310-1318
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• 2012

This study presents a new system that can make up for the decrease in identification rate due to the environmental or physical factors of a fingerprint identification system, which is most actively used among existing biometric systems. Considered most usable in life among many types of biometrics due to the convenience of use, smaller initial investment, and the smaller size, fingerprint identification is widely used in diverse applications. However, a fingerprint identification system has several defects, including environmental factors, physical skin damage, and variable sensor contact, lowering the identification rate in comparison to other biometric systems. On the basis of the existing fingerprint system, this study presents a more efficient system that can improve the identification rate by getting additional biometric information and three-dimensional finger type information through the use of simple and inexpensive additional equipment, which can be used in diverse areas.