• Journal of Korea Foundry Society
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• v.5 no.2
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• pp.109-117
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• 1985

A two dimensional analysis of the solidification phenomena has been simulated by IAD (Implicit Alternating Direction)method for L-shaped castings with external chills. The effect of chills has been studied with the variation of chill size, shape, and their materials, and also with the variation of the pouring temperature. Three kinds of cross-sectional shapes of chills such as triangle, square, and L-shape were chosen, and graphite, cast iron, and copper for their materials. It has been shown by the computation that the hot spot at the junction of L-shaped castings can not be removed by external chills, and that the distance between the inner corner and the hot spot on the line of symmetry, as well as the solidification time of castings depend only on VHC (Volumetric Heat Capacity).

• Journal of The Korean Digital Architecture Interior Association
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• v.8 no.1
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• pp.57-64
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• 2008

There are many problems in present truss-deck slab system for example welding defect, segregation, water leakage, rust and tarnish etc. These problems may be caused by spot welding thin galvanized steel plate and lattice bar. The TOX Joining Systems is to join metal sheets of different material and thickness with and without coating or painting without adding heat or a joining part. Newly developed TOX-deck slab system using non-welding joint is free from above mentioned problems. The objects of this study are suggestion of design strength of TOX joint by experimental and statistical analyses and development of window based program to design the TOX-deck slab system.

• Applied Science and Convergence Technology
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• v.24 no.5
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• pp.136-141
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• 2015

We studied the compact anode design to develop 100 kW rotating anode X-ray tube with large focal spot 1.2 mm, small focal spot 0.6 mm and tube voltage 150 kV for large hospital digital radiography using computer thermal simulation. The larger thermal radiation effect in a high vacuum can reduce the temperature of anode so the method to increase the surface area of anode is investigated. The anode has the multi-tier shape at the back side of TZM body of anode and also bigger diameter of anode. The number of multi-tiers was varied from 6 to 15 and the diameter of anode was also varied from ${\Phi}74$ to ${\Phi}82$. From ANSYS transient thermal simulation result, we could obtain $1056.4^{\circ}C$ anode maximum temperature when applying 100 kW input power at 0.1 second on target focal track which is less than $1091^{\circ}C$ of the conventional 75 kW X-ray tube with reduced anode weight by 15.5% than the conventional anode. The compact anode of reduced anode weight is able to improve the unwanted noise when the rotor is rotating at high-speed and also reduce the rotational torque which the cost effective stator-coil is possible. It is believed that the anode with 15 ea multi-tiers using ${\Phi}82$ can satisfy with the specification of the anode heat capacity. From the results of this paper, it has been confirmed that the proposed compact anode can be used as the anode of 100 kW rotating anode X-ray tube for digital radiography.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.61-71
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• 2022

Pool boiling heat transfer is widely applied in nuclear engineering fields. The influence of heating surface orientation on the pool boiling heat transfer has received extensive attention. In this study, the heating surface with different roughness was adopted to conduct pool boiling experiments at different inclination angles. Based on the boiling curves and bubble images, the effects of inclination angle on the pool boiling heat transfer and critical heat flux were analyzed. When the inclination angle was bigger than 90°, the bubble size increased with the increase of inclination angle. Both the bubble departure frequency and critical heat flux decreased as the inclination angle increased. The existing theoretical models about pool boiling heat transfer and critical heat flux were compared. From the perspective of bubble agitation model and Hot/Dry spot model, the experimental phenomena could be explained reasonably. The enlargement of bubble not only could enhance the agitation of nearby liquid but also would cause the bubble to stay longer on the heating surface. Consequently, the effect of inclination angle on the pool boiling heat transfer was not conspicuous. With the increase of inclination angle, the rewetting of heating surface became much more difficult. It has negative effect on the critical heat flux. This work provides experimental data basis for heat transfer and CHF performance of pool boiling.

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.32-32
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• 2003

소 난자의 체외성숙 과정에서 세포질 내 단백질의 생산과 축적의 변화는 핵 및 세포질 성숙과 밀접한 관계가 있다는 보고가 있지만, 난자의 성숙과 관련된 특정 단백질의 종류에 대한 보고는 없었다. 따라서 본 연구는 한우 난자의 체외성숙과 관련된 단백질의 생산 및 축적의 변화와 그 종류에 대해서 검토하였다. 체외성숙 시간(4.5, 9, 13.5, 18 및 24시간)에 따른 배양액 내의 단백질 합성의 변화는 2D gel electrophoresis를 이용하였고, 단백질 spot에 대해서는 peptide mass fingerprinting(PMF) 방법을 이용하였다. 또한 단백질 측정 시간에 신선 체외성숙 배양액으로 교환 후 난포란의 핵성숙과 배발달율을 검토하였다. 그 결과 한우 난포란의 체외성숙 시간에 따라 배양액에서 단백질의 양 및 질적인 변화를 확인하였다. 그리고 총 296개 단백질 spot들을 확인하였고, 그 중 30개 spot에서 유의적인 변화가 인정되었다. 또한 유의적인 변화를 보인 spot에 대한 PMF 분석을 통하여 Apolipoprotein A-1 precursor, Alpha enolase, Aldose reductase, 43kDa collectin precursor, Heat shock 27kDa protein, Plasminogen activator inhibitor-1 precursor, Thrombospondin 1 및 Transitional endoplasmic reticulum ATPase가 동정되었다 그리고 총 단백질 합성 경향은 0∼4.5 시간에는 감소하였고, 13.5∼18시간에 증가 한 후 다시 감소하는 경향을 나타내었으며, 단백질의 종류도 시간대별로 현저한 변화가 있었다. 한편 단백질을 측정하는 시기에 신선 체외성숙 배양액으로 교환한 후 난포란의 핵성숙 및 배발달율을 검토한 결과 18시간 체외성숙군에서 9시간째의 교환이 유의적으로 높은 핵성숙을 나타내었으나, 배발달율에서는 유의성이 인정되지 않았다. 그러나 24시간 체외성숙군에서 18시간째의 배양액 교환은 8세포기 및 배반포 발달율이 유의적(P<0.05)으로 높았다. 연구 결과로부터 소 난자의 체외성숙 시간에 따른 단백질 합성 경향의 차이를 확인하였고, 유의적인 변화를 나타낸 8가지의 단백질을 분리할 수 있었으며, 향후 이들 작용기전에 대한 연구가 필요하다고 사료된다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.9
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• pp.103-110
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• 2008

In terms of electrical safety, environmental impact assessment and revision of domestic regulation are needed for the electric facilities. In this paper, risk of electric facilities is assessed by the spot measures and analysis in dust generation area. Adhesion dust in a surface of insulated materials cause electrical accidents. In a mechanism of these accidents, when the dust lie on electric facilities, a leakage current is flowed and the surface of insulated material is carbonized. Hereafter, electrical fire is generated due to Joule's heat. As the results, dusts are found in protection devices or panel board and sampled dusts vary in sampled amounts and conductivity severally. For the most part, sodium is detected but zinc and calcium are detected in case of reclaimed rubber factory by the ICP-AES(Inductively Coupled Plasma-Atomic Emission Spectroscopy). In a sewerage, the ingredients such as sodium, magnesium, iron, calcium, aluminium, etc are detected uniformly. So that, results of the spot measures and analysis of dusts are become the important data for the assessment of electrical hazard in dust generation area.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.1
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• pp.53-62
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• 1987

High power lasers provide a controllable and precise energy source in surface transformation hardening. A careful control of the process is needed in order that the surface layer of the material reaches the austenizing temperature, but that it does not melt. In order to achieve this the results of theoretical and experimental studies on the laser surface hardening of a medium carbon steel are described. A two-dimensional computer program, which can be used generally for the determination of transient temperature distributions in welding and heat treatment, was established on the basis of the finite element method. For the confirmation of the accuracy of the numerical analysis, a medium carbon steel (SM 45C) of 5mm thickness was heat-treated with a 1kW CW CO$_{2}$ laser machine, while the traverse speed and the distance from the focal point (defocused distance) were varied. Experimental and numerical results showed a similar tendency in correlations between the hardened zone shape and the process parameters. With increasing beam spot diameter the width and depth of the hardened zone increased for relatively small beam spot diameters, but decreased rapidly after reaching the maximum value, while with increasing traverse speed the width and depth of the hardened zone decreased monotonously. Too small beam spot diameters are to be avoided, since the surface melting would lower the surface hardness and produce an uneven surface which may be unacceptable because of the possible requirement for subsequent machining. It could be observed that for a given traverse speed and laser power input there exists a optimal range of the beam spot diameter, which produce a large width of the hardened zone but no melting on the surface.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.239-246
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• 2013

The purpose of this study was to find out the potential of the Mosidae(Adenophora remtriflora) leaf, one of the natural ingredients, for the cosmetics by measuring their antioxidant functions and skin improving effects. The result of the phytonutrient of the Mosidae leaf test shows, that the heat extract of Mosidae leaf DPPH has 9% higher ability than Ethanol extract.(p<0.05), but significant a difference was not found between the hydroxyl Radical of Mosidae leaf heat extract (65.22%) and Ethanol extract(63.50%). Mosidae leaf heat extract(40.82mg/mL) has much lower polyphenol compound than Ethanol extract(47.90mg/mL)(p<0.05). A clinical test of Mosidae leaf powder pack was performed for a group of 16 middle aged women(age between 35-60) from October 20 to November 17, 2011. Control group was used on the right cheek, and test group was used on left cheek for comparison. The procedure was twice a week for 4 weeks to identify and grade level of moisture, roughness, pore size and spot. After 4 weeks of testing, there were significant improvements in moisture enhancement and spot(p<0.05), subtle change in roughness and the size of the pores. Therefore, we confirmed skin improvement effect of Mosidae leaf as new cosmetic material.

• Korean Journal of Metals and Materials
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• v.49 no.1
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• pp.64-72
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• 2011

The spot weldability of dissimilar metal joints between austenitic stainless steels (STS316)/IF steels and ferritic stainless steels (STS430)/IF steels was investigated. This study was aimed to determine the spot welding parameters for a dissimilar metal joint and to evaluate the dissimilar metal joint's weldability, including its welding nugget shape, tensile-shear strength, hardness, and microstructure. The comparison of these results was described in terms of fracture behavior. Compared with the weld lobe of similar metal joints, dissimilar metal joints (STS430/IF) had reduced weld current range. However, the weld lobe of STS316/IF steel joint showed increased weld current range. This is because the dilution of chemical composition in the molten weld pool suppressed the heat input being caused by Joule heat with current flow through the samples. The microstructure of the fusion zone was fully martensite and mixture of ferrite and martensite for austenitic stainless steel/IF steel and ferritic stainless steel/IF steel combination, respectively. The experimental results showed that the shape of nugget was asymmetric, in which the fusion zone of the austenitic and ferritic stainless steel sheet was larger due to the higher bulk-resistance. The predicted microstructure by using the Schaeffler diagram was well matched with experimental results. After peel test, the fracture was initiated from heat affected zone of ferritic stainless steel sheet side, however the final fracture was propagated into the IF steel sheet side due to its lower strength.

• The Journal of Korean Physical Therapy
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• v.22 no.6
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• pp.77-83
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• 2010

Purpose: The aim of this study was to do numerical analysis of the wavelength dependence in low level laser therapy (LLLT) using a finite element method (FEM). Methods: Numerical analysis of heat transfer based on a Pennes' bioheat equation was performed to assess the wavelength dependence of effects of LLLT in a single layer and in multilayered tissue that consists of skin, fat and muscle. The three different wavelengths selected, 660 nm, 830 nm and 980 nm, were ones that are frequently used in clinic settings for the therapy of musculoskeletal disorders. Laser parameters were set to the power density of 35.7 W/$cm^2$, a spot diameter of 0.06 cm, and a laser exposure time of 50 seconds for all wavelengths. Results: Temperature changes in tissue based on a heat transfer equation using a finite element method were simulated and were dominantly dependent upon the absorption coefficient of each tissue layer. In the analysis of a single tissue layer, heat generation by fixed laser exposure at each wavelength had a similar pattern for increasing temperature in both skin and fat (980 nm > 660 nm > 830 nm), but in the muscle layer 660nm generated the most heat (660 nm ${\gg}$ 980 nm > 830 nm). The heat generation in multilayered tissue versus penetration depth was shown that the temperature of 660 nm wavelength was higher than those of 830 nm and 980 nm Conclusion: Numerical analysis of heat transfer versus penetration depth using a finite element method showed that the greatest amount of heat generation is seen in multilayered tissue at = 660 nm. Numerical analysis of heat transfer may help lend insight into thermal events occurring inside tissue layers during low level laser therapy.