• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 추계학술대회 논문집
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• pp.205-208
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• 2002

Thermal design is required with considering thermal stability to verify the reliability of electric power device with using IGBT. Numerical analysis is performed to analyzed the change in thermal resistance with respect to the various thermal density of heating element. Correlations between thermal resistance and heat generation density are established. With using these correlations, performance curve is composed with respect to the change in thermal resistance of cooling conditions for natural convection and forced convection. Thermal fatigue is occurred at the Inside and outside of IGBT by repeated heat load. The crack is occurred between base plate and ceramic substrate for the inside. When the crack length is 4mm, the failure is occurred. Therefore, Thermal design method considering thermal density, thermal fatigue resistance is presented on this study and it is expected to thermal design with considering life prediction.

• 동력기계공학회지
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• 제10권1호
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• pp.77-82
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• 2006

In this study, dissimilar friction welding were produced using 15mm diameter solid bar in chrome molybedenum steel(SCM440) to carbon steel(S45C) to investigate their mechanical properties and the relationship between the weld parameters and the nondestructive coefficients, such as AE counts and ultrasonic attenuation coefficient. The main friction welding parameters were selected to endure good quality welds on the basis of visual examination, tensile tests, Vickers hardness surveys of the bond of area and heat affected zone. The specimens were tested as-welded and post weld heat treated(PWHT). The tensile strength of the friction welded steel bars was increased up to 100％ of the S45C base metal under the condition of all heating time. The ductility of PWHT specimens is higher than as-welded.

• Journal of Welding and Joining
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• 제10권3호
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• pp.26-39
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• 1992

Diffusion bonding of Mo was performed by using the metallic coating of Cu and Cr on the surface to be bonded. Joint characteristics of Mo with or without coating layer were compared in metallurgical and fractograpical aspects. The results showed that the diffusion bonding with coating layer, especially with Cu coating, increased the bending strength of joint. Variation of heating cycle(elevation of temperature for a moment) did not affect significantly the mechanical properties of joint. Fractographical analysis showed that the fracture of joint bonded with Cr coating occurred at the coating layer, while that with Cu coating occurred at the base metal.

• Bulletin of the Korean Chemical Society
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• 제12권5호
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• pp.583-588
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• 1991

A series of dimesogenic compounds having two identical, terminal Schiff base type mesogens and a central polymethylene spacer were prepared and their properties were compared with those of the corresponding monomesogenic compounds. The mesomorphic properties of the compounds were studied by differential scanning calorimetry and on a hot-stage of a polarizing microscope. All of the dimesogenic compounds formed mesophases enantiotropically with the exception of pentamethylene-1,5-bis(4-oxybenzylidene 4-n-butylaniline). This compound was monotropic and formed only a nematic phase on heating the solid, whereas it formed nematic as well as smectic A phases on cooling the isotropic liquid. Those compounds containing longer (octamethylene and decamethylene) spacers favored the formation of nematic phase whereas those having shorter (dimethylene and tetramethylene) spacers formed smectic phases. In general, the variety of mesophase forms exhibited by the dimesogenic compounds was significantly less than that shown by the corresponding monomesogenic compounds.

• 한국지열·수열에너지학회논문집
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• 제17권1호
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• pp.1-13
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• 2021

Before newly-built building and building remodeling, it is important to predict and analyze building energy performance through energy simulation programs. Nevertheless, simulation results widely vary depending on individual user experience and input values. Therefore, this study uses prototypical building model, a versatile tool in building energy modeling, simulation and research for researchers and policy-makers, and ASHRAE standards. Then, it analyzed the changes in design type (roof type, number of floors) for the base case. As the result, it was found that the gap of annual energy demand per between them is maximally 9.1%.

• 한국한의학연구원논문집
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• 제13권2호통권20호
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• pp.113-120
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• 2007

1. 뜸 특허의 한국 출원인은 타국가의 특허에 비해 자국내 집중적인 출원 양상을 보이고 있었고 국적별 출원 점유율에서는 한국 국적 출원인이 전체 80%의 출원 점유율을 보였다. 2. 분야별 특허 점유율에서는 뜸구(587건) 26%, 가열수단(495건) 23%, 가열제어(96건) 4%, 제조방법(78건) 및 기타(70건)가 각 3%로 나타났다. 3. 뜸 특허 다출원자로는 한국의 유태우, 김근식이 가장 많았고, 일본에서는 Kamaya Mogusa, Obika Reiko, 미국에서는 유태우, Shimada 및 Osamu 인 것으로 나타났다. 4. 뜸 연소재에서 가장 많은 출원을 한 종류는 ‘쑥’ 이었고, 가열제어 분야의 ‘쑥뜸기’가 가장 많이 출원되었다.

• 유기물자원화
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• 제16권1호
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• pp.70-78
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• 2008

본 연구에서는 경기도 B지역 학교 폐기물의 성상 및 물리 화학적 특성을 조사하였다. 이것은 폐기물 재활용 및 자원화시설 설계를 위한 기초자료로 활용할 수 있게 하고자 한다. 학교폐기물의 물리적 조성의 실험결과 음식 쓰레기 12.25%, 종이류 56.26%, 플라스틱과 비닐류 9.26%, 섬유 1.52%, 나무 3.70%, 고무 및 피혁류와 기타는 0.11%이다. 학교폐기물의 대부분은 종이류와 플라스틱류이고, 약 90%가 가연성분인 것으로 나타났다. 삼성분 분석 결과 수분 5.72%, 가연분 88.29%, 그리고 회분 5.98%로 나타났으며, 농촌지역 학교 폐기물 성분중 수분이 도시지역 학교보다 높게 나왔다. 건조된 폐기물의 원소 분석 결과 탄소, 산소, 수소가 높게 나왔으며 학교폐기물의 저위발열량은 3051.44kcal/kg로 조사되어졌다.

• 한국환경복원기술학회지
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• 제12권4호
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• pp.72-80
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• 2009

The main purpose of this study is as follows : Finding a solution for fresh wood chips to be used as an alternative growing-media through a study of the formation method of a compost base that is applicable on both construction site and composting factory to ferment fresh wood chips produced from construction site as well as a study on adjuvant or secondary materials. The result from the experiment plot using wood chips sized 50mm or less, manure and fertilizer mixed manure as a source of nitrogen to compost fresh wood chips has shown that the temperatures 9days and 3days after the beginning of the experiment reached to $49.0^{\circ}C$ and $40.4^{\circ}C$ respectively, the heating duration was 7days and 4days respectively, and the C/N ratio was 26.5 and 25.3, each satisfying the standard for composted manure (25.0~40.0). Also, the other result from another experiment plot using mixture of sandy soil and microorganism as an inoculation source of microorganism has shown that the temperature 10days after the beginning of the experiment reached to $67.6^{\circ}C$ and lasted 16days. The experiment plot using sandy soil has shown the highest figure of $5.3{\sim}108$ CFU/g in terms of number of microorganism. The result from the experiment plots for on-site composting of fresh wood chips have shown that the experiment plot that used sandy soil with fertilizer due to supply restriction of manure as a nitrogen source in construction site reached the high temperature of $54.7^{\circ}C$ after 3days of experiment beginning and maintained heating state for 17days and reached 30.6 of C/N ratio, satisfying the standard for composted manure.

• 한국정밀공학회지
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• 제24권4호
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• pp.115-122
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• 2007

Recently, remarkable progress has been made in both technology and production of optical elements including aspheric lens. Especially, requirements for machining glass materials have been increasing in terms of limitation on using environment, flexibility of material selection and surface accuracy. In the past, precision optical glass lenses were produced through multiple processes such as grinding and polishing, but mass production of aspheric lenses requiring high accuracy and having complex profile was rather difficult. In such a background, the high-precision optical GMP process was developed with an eye to mass production of precision optical glass parts by molding press. This GMP process can produce with precision and good repeatability special form lenses such as camera, video camera, aspheric lens for laser pickup, $f-\theta$ lens for laser printer and prism, and me glass parts including diffraction grating and V-grooved base. GMP process consist a succession of heating, forming, and cooling stage. In this study, as a fundamental study to develop molds for GMP used in fabrication of glass lens, we conducted a glass lens forming simulation. In prior to, to determine flow characteristics and coefficient of friction, a compression test and a compression farming simulation for PBK40, which is a material of glass lens, were conducted. Finally, using flow stress functions and coefficient of friction, a glass lens forming simulation was conducted.

• 동아시아식생활학회지
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• 제1권1호
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• pp.17-29
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• 1991

The Hong's-Zu-Bang-Moon, although it is not know when and by whom it was written, is estimated to have written in the middle of 1800, but has not been published yet. In general, other cooking books in Yi's Dynasty were on the cooking methods of a variety of foods. But the book deals solely with brewing, which is the trait of it. The book comprises a total of 36 items, among which So-Gog-Ju wine was excluded because only a part of it was recorded. Another item deleted, written vaguely and difficult to understand was, on a closer analysis of its content, 'Song-Soon-Ju wine'. According to the analysis of this book, the cereals used for brewing were 59 percent of regular rice and 41 percent of sticky rice including other 12 kinds of special materials. As for the processes, the precesses using Jee-Ae-Bop was dominant. The processing technique whose special words and expressions were analyzed in this study, were divided into 18 preparation methods, 45 processing ones, and 7 heating ones. The temperature processing whose expressions were analyzed here were divided into 6 cooking processes, 7 medium ones and 3 heating ones. The measurement unit of 'Doe' was most often used. It tried to show relatively accurate measurements but showed just approximate ones. There were 19 kinds of brewing utensis. Urns were most often used, but it was impossible to discern and kind. As for the tast of the wines, the writer showed his subjective expressions. The margianal point in this study is that it was very difficult to interpret the book. The closing up of twings of on azaled over the urn had no scientific base but said something of korean folkways at that times.