• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.3
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• pp.213-219
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• 2008

Microscale heat transfer and microfluidics have become increasingly important to overcome some very complex engineering challenges. The use of very small passages to gain heat transfer enhancement is a well documented method for achieving high heat flux dissipation. In this study, the performance evaluation of micro-channel plated heat exchangers with straight, V-shaped and Y-shaped channels has been experimentally carried out under the counterflow condition. It is found that the mixing effect in V-shaped and Y-shaped channels enhances the heat transfer but pressure drop does not increase seriously in the range of low Reynolds number.

• Korean Journal of Heritage: History & Science
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• v.54 no.3
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• pp.242-261
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• 2021

Sangjeong was a sculptor-monk who was active in the mid-to-late 18th Century, and the current study established the overall chronology of Sangjeong's Buddhist statues and their styles based on the six sculptures of Sangjeong already known and the Wooden Seated Buddha of 1767 in Songgyesa Temple, Geochang, which was found to be his last work. All of the Buddhist statues of Sangjeong have commonalities in terms of the appearance of the ears, wrinkles on clothing on the upper and lower body, position of hands, and expression of the lower body. The expression of the lower body, in particular, is classified into three types: Type A, where the clothing drapes through the lotus leaves on the bottom; Type B, with an 'S-shaped' drape over the lower body but no lotus leaves or pedestal; and Type C, with the Buddha and pedestal as a single unit, and the clothing draping through the lotus leaves on the pedestal. It appears that Sangjeong faithfully succeeded the style of Taewon, who was his only instructor for sculpture. This is verified based on the records of his participation in the creation of the Wooden Seated Sakyamuni Buddha Triad and Statue of Arhat in Bongeunsa Temple, Seoul, as the third sculptor-monk out of twelve sculptor-monks, and the reflection of the S-shaped drape on the lower body found on the statue of Buddha in Bongeunsa Temple on all of the statues created by Sangjeong. Not only that, but it was assumed that the expression of the pedestal and hair was also inherited by Sangjeong from Taewon and Jinyeol, who was a sculptor-monk from the early 18th Century. The work of Sangjeong and Taewon showed differences in the volume and thickness of statues, strength of unevenness on the wrinkles of clothing, drapes on the right side of chest, and details of the ears. The current study identified the original styles of each individual sculptor and attempted to categorize the fourteen pieces of ten Buddhist statues reflecting the styles of Sangjeong into Sangjeong-style or Taewon-style.

• Composites Research
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• v.29 no.5
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• pp.236-242
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• 2016

In this work, tensile and in-plane shear tests for thermoplastic glass fiber/polypropylene composites were performed at a thermo-forming temperature and their properties were characterized and mathematically expressed by using the non-orthogonal constitutive model. As for the thermo-forming test, half-dome experiments were carried out by varying the usage of a releasing agent and the weight of holders. As results, the optimum final shape having well-aligned symmetry and no wrinkle formation was obtained when the releasing agent was used, and it was found that the careful control of a holding force is crucial to manufacture the healthy product. Furthermore, FEM simulations based on the non-orthogonal model showed similar final shapes and tendency of wrinkle formation with experimental results, and confirmed that wrinkles increase with less holding force and higher punch force is required under high frictional condition.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.150-150
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• 2016

디스플레이, 센서 등 전자소자는 소형화 단계를 지나 인체 부착형 소자로의 발전을 요구하고 있다. 부착형 소자에서는 접착력과 큰 마찰력이 필요하지만 마찰특성이 더 중요하므로 인체 및 물체의 마찰을 위해서는 다양한 표면에 대항하는 마찰 특성과 내구성이 요구되며 이를 위해 개코도마뱀 또는 딱정벌레, 말벌날개와 같은 자연모사형 건식 마찰 방식에 대한 연구가 활발히 진행되고 있다. 그러나 기존 폴리머를 이용하여 자연모사형 마이크로/나노 구조 형성은 기계적으로 가공된 금형 몰딩을 통한 매무 복잡한 공정을 요구된다. 본 연구에서는 이러한 복잡한 공정을 통한 마찰재 제작을 단순화하기 위해서 플라즈마 표면처리를 활용하여 나노구조 형성하는 방법을 소개하고자 하며, 건식 접착 및 마찰용 폴리머 소재(PDMS(Poly dimethyl siloxane))에 따른 표면구조 변화와 표면에너지 및 화학결합 변화에 대한 연구를 수행하였다. 플라즈마 표면처리를 위해서 자체 개발한 선형이온소스를 활용하였으며 입사에너지에 따라 표면형상 변화를 주사전자현미경을 활용하여 관찰하였다. 표면에너지 변화는 접촉각측정기를 활용하였으며, Tribology tester(Ball on disk)를 활용하여 마찰특성을 평가하였다. PDMS(Poly dimethyl siloxane)는 입사에너지가 증가함에 따라 주름형태 구조 크기가 증가하는 것을 관찰하였고, 플라즈마 처리를 통해 표면에너지 및 마찰력 증가를 관찰하였다. 그리고 플라즈마 처리 후 표면에너지 변화인 FOTS(Trichloro-(1H,1H,2H,2H- perfluorooctyl) silane) 처리를 통하여 표면에너지 감소와 마찰력이 절반으로 감소하였다. 본 연구 결과는 나노구조에 따라 표면형상 및 표면에너지 변화에 따른 PDMS의 마찰력 변화를 확인하였고, 이러한 특성을 활용하여 마찰재와 피부 부착형 접착 패치에 응용이 가능할 것으로 기대된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.450-455
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• 2017

A shield connector is an automotive electrical component that is used to connect electrical wiring in a vehicle. This part is made by progressive pressing using a phosphor bronze material with high electrical conductivity. The shape of the product is not complicated, but plastic forming techniques are required, such as deep drawing and bending, as well as shearing techniques such as piercing and notching. The finite element method was used to model the process. The strip layout design stage of the progressive die makes it possible to examine the thickness change, the stability of the forming process, and the spring-back. As a result of this analysis, it is possible to predict the correction values for the tendency of cracks, wrinkles, and incomplete plastic deformation, and to identify possible problems in advance. As a countermeasure against the forming error caused by the drawing process analysis, the drawing shape was modified and applied in the process design. For effective material utilization, a 3D strip layout was designed using an optimized blank shape based on nesting. The results improve the crack stability and spring-back of shield connector products produced through progressive pressing.

• Composites Research
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• v.31 no.5
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• pp.209-214
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• 2018

This paper explain about the development of environmental friendly, low cost and stable supply material i.e., rice husk and shell were used as micro incorporating bio waste filler. Those were processed by ball mill and analyzed through micro observation by FE-SEM, EDS and particle size distribution. The obtained filler was mixed with epoxy resin for the manufacturing of CFRP composite and study tensile properties. In EDS analysis main contents of rice husk and rice husk ash are C, O and Si. When rice husk was burned C and Si ration were increased. Shell powder has C, O and Ca. It caused $CaCO_3$ from shell. Surface weighted mean of rice husk powder is $6.19{\mu}m$ and volume weighted mean is $14.77{\mu}m$. And it has rod type particles which caused hair and husk structure parts. Surface weighted mean of rice husk ash powder is $1.55{\mu}m$ and volume weighted means is $8.20{\mu}m$. Surface weighted mean of shell powder is $2.53{\mu}m$ and volume weighted mean is $5.79{\mu}m$. The tensile decreased with increasing the content of micro filler in CFRP composites. In case of rice husk, the significant decrement of tensile strength was observed. and in case of shell powder, there is no effect of changes take place in tensile strength.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.173-179
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• 2019

DICOM(Digital Imaging and Communications in Medicine) imaging plays a significant role in the diagnosis and treatment of the human body, and design modeling is a technology of planning shapes in three dimensions according to the purpose. In this study, we converge these two technologies to observe the relationships of the cross-section, volume, and surface area to the morphological changes of the external ear canal. The experiment applied medical imaging technologies to acquire sections of the human body to create and divide centerlines using 3D shapes extracted from 19 external ear canals by applying stereolithography and 3-matic program. The results showed that the cross-sectional structure of the external ear canal had various shapes, such as oval (38.5%), semicircular (28.2%), mixed (17.9%), square (10.2%), and wrinkled (5.1%). In addition, the cross-sectional area of each phase increased as the length of the external ear canal increased, and the volume and surface area decreased towards the direction of the eardrum. However, the surface area reduction rate was relatively low. This indicates that the structure becomes irregular towards the direction of the eardrum.

• Journal of the Korea Fashion and Costume Design Association
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• v.7 no.1
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• pp.33-40
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• 2005

Gathering is method used to control fullness along a seam line. The purpose of this study was to investigate the relationship between the quantitative research and qualitative method; the effect of gather and the types of gather drape. The experimental design consists of four factors: (l) three kinds of different weight and thickness of fabrics (2) three kinds of stitch densities (3) five kinds of ratio of gathers (4) three kinds of grain directions. Therefore one hundred thirty five (135) samples were made. And utilized SPSS WIN 10.0 Package in data analysis. The results of this study were as follows; First, after frequency analysis, side height, hem line width, node depth, node count, node width accorded with these result data recording. Second, after correlation analysis, side height related with front statements. Side height and entire visual was negative correlation. Hem line width, node depth, node count with section statements was negative correlation but node width at section statements was positive correlation. Third, after $k^2$ analysis, front picture parts getting excellent evaluation were 1st side height, 3rd hem line width, 4th node depth, 3rd node count, 3rd node width. And section illustration parts getting excellent evaluation were 4th side height, 1st hem line width, 2nd node depth, 3rd node count, 4th node width.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.8
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• pp.790-796
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• 2013

Micro-speaker diaphragms play an important role in generating a desired audio response. The diaphragm is generally a circular membrane, and the cross section is a double dome, with an inner dome and an outer dome. To improve the sound quality of the speaker, a number of corrugations may be included in the outer dome region. In this study, the role of these corrugations is investigated using two kinds of finite element method (FEM) calculations. Structural FEM modeling was carried out to investigate the change in stiffness of the diaphragm when the corrugations were included. Modal FEM modeling was then carried out to compare the natural frequencies and the resulting vibrational modes of the plain and corrugated diaphragms. The effects of the corrugations on the vibration characteristics of the diaphragm are discussed.

• The Journal of the Korea Contents Association
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• v.18 no.1
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• pp.359-369
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• 2018

When expressing Christ visually in the medieval Christian painting, the most important issue was how to express the divinity as Son of God and the humanity as attribute of human in a balanced manner. The purpose of the study is to examine both formative and symbolic characters of divinity and humanity on the Christ's body and clothes in the Medieval paintings, Transfiguration of Christ. In the paintings, Christ's body is definite evidence to show both his divinity and humanity. In connection with the body, the clothes reveal Christ's humanity and divinity as well. Through this research, the study found that the divinity and humanity on the Christ's clothes in the Transfiguration of Christ were as follows: Blue, gold, purple, white and bleaching effect are the emblem of divinity, and red and color contrast effect with a high chroma stand for humanity of Christ. In addition, unstructured wrinkles of clothes reveal Christ's divinity, on the other hand, structured drapery shows his humanity through emphasizing volume of the body. Finally, divinity of Christ is shown on the gold clavus and red clavus intensify his humanity. Medieval Christian paintings are products planned out to express Christ's dual nature. There is a significance that the paintings represent the profession of painter's faith and the dogma of the era. Furthermore, they suggest the importance of the image to deliver the abstract concepts by visualizing.