• Journal of Energy Engineering
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• v.20 no.2
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• pp.96-102
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• 2011

This research has been proceeded over the transition region(H/B=10) of two-dimensional impinging air jet system, in which square rods has been set up in front of heating surface in order to increase heat transfer. The objective of this research was to investigate the characteristics of heat transfer and air flow, in cases the clearance from rods to heating surface(C=1, 2, 4, 6 mm) and the width of rods(W=4, 6, 8 mm) changed. And this research compared the above with the experimentation without rods. As result, heat transfer performance was best under the condition of C=1 mm, and as the width is 8 mm, it is largely influenced by eddies and acceleration in case width of rods changed.

• Solar Energy
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• v.15 no.3
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• pp.127-140
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• 1995

This experimental study was carried out to examine the heat transfer characteristics of a 2-dimensional impinging air jet on a flat plate with a set of square rods. The objectives of the study were to investigate the flow and heat transfer characteristics caused by the square rods. Experiment was carried out first without using the rods to establish the baseline heat transfer performance. Then, rods of different widths and clearances were installed to cause the turbulence on the fluid flow. When rods are installed in front of the plate, the acceleration of the flow and the turbulence generation due to the rods and reattachment of the flow seem to contribute to the observed heat transfer augmentation and the heat transfer augmentation increases as the clearance decreases. With wider individual rod the heat transfer coefficient is higher, which is due to the increased acceleration and development of the eddies just before the rods.

• 한국공간정보시스템학회:학술대회논문집
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• 1999.06a
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• pp.203-214
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• 1999

위성영상의 종류가 많아지고 다양한 종류의 수치지도가 생성되고 관리되기 위해서는 지도도서관이 필요할 것이며, 이는 클리어링하우스와는 달리 전통적인 종이지도까지 포함이 되어야한다. 상품화된 GIS 툴에서 제공하는 공간검색의 기능을 개발하여 지도도서관에 활용을 한다면, 지명검색보다 다양한 형태의 자료를 검색하여 비교할 수 있으므로, 데이터베이스에 각 자료의 좌상단, 우하단 좌표가 입력 관리되고, 서버에 모든 자료가 존재한다는 가정하에 사각검색과 원 검색의 원리를 경우에 따라 분류하고 SQL문으로 만드는 원리를 정리하였다. 공간검색을 통한 GIS자료의 다운로드와 생성된 자료의 업로드 기능을 클라이언트/서버환경에서 JDBC를 활용하여 구현하였다. 국가기관이나 학교에서 지도전문 도서관이 전무한 실정이지만, 앞으로의 가능성을 전제로 하여 고지도로부터 관광지도, 수치지도, 위성영상을 활용한 주제도에 대한 관리방법으로 제안한다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.6
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• pp.585-597
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• 2014

In this study, the cutter acting forces were measured by 3-directional load cell at two different skew angles and various S/d ratios during a series of linear cutting tests using a slim conical pick. The analysis for cutting performance were carried out after calculating average values of the measured results. The increase of penetration depth results in the decrease of specific energy. And the variations of the cutter acting forces depending on penetration depth in the case of 6 degree skew angle were smaller than in the case of 0 degree skew angle. From this results, 6 degree skew angle is more effective than 0 degree skew angle in designing optimal specifications of cutting head. In addition, $F_c/F_n$ under the setting of 6 degree skew angle was smaller than under the setting of 0 degree skew angle. However, it should be considered that the increase of cutter acting force in the cutting direction accompanied the increase of driving force in the case of the setting for 6 degree skew angle.

• Science of Emotion and Sensibility
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• v.23 no.4
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• pp.117-142
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• 2020

This study aims to look for the main transport road of the ancient Silk Road and to add to the hidden history of silk, where little is known about the weaving technology of the beautiful silk of GoJoseon. The research was through the analysis of relics of empirical data and analyzed the secondary data collected from books, papers, and photos of artifacts. The research questions are as follows: First, investigates the environment of silk production for GoJoseon KyungGeum and the correlation between ancient Silk Road and the East region. Second, examines the advanced weaving technology of KyungGeum in GoJoseon. The findings of the study are as follows: It is possible to infer the production period of silk in GoJoseon through jade silkworms from the Hongsan Dong-Yi culture of 4500 BC. KyungGeum pieces were excavated in Louran, Astana and Niya of the Xinjiang Autonomous Region and Noin-Ula of Mongolia, and the oldest KyungGeum was found in JoYang, one of the capitals of GoJoseon near Balhae Bay. KyungGeum was invented in the 11th century BCE here. It became the brocade and damask of the West, which were delivered through steppe road before the 5~6th century BCE. The production of KyungGeum was possible through the advanced loom which is GoJoseon's horizontal square 'Jewharu' loom combined with a high level of weaving skill. This can't be made through the slant loom of China nor vertical loom of the West Asia. Based on these results, it is suggested to continue the research on the history of ancient silkroad.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.2 no.2
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• pp.107-113
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• 2001

This work presents field-dependent Bingham and response characteristics of MR fluids under shear and flow modes. Two different types of magneto-viscometers are designed and manufactured for the shear and flow modes. respectively. For the MR fluid to be tested, MRF-132LD of Lord co. is employed. The field-dependent yield stress is experimentally distilled at various temperatures using the magneto-viscometers. Time responses of the MR fluids to step electric fields are also evaluated under two operating modes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.2
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• pp.142-149
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• 2013

The thrust vector control technique is essential for high maneuverability of unmanned aerial vehicles. In the present study, a multi-component balance was developed to quantitatively evaluate the thrust-vectoring performance of a supersonic rectangular nozzle based on the Coanda coflowing effect. Precise calibration and detailed data analysis were performed during the development. It was found that the cross-talk errors between load cells in the balance were less than 5%, and that the unwanted errors due to high-pressure supply tubes were almost negligible, which contributed to the high accuracy of the present balance design. Some preliminary test results of the thrust-vectoring performance of the present nozzle design were also obtained and analyzed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.2
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• pp.221-233
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• 2016

In order to estimate the performance of a conical cutter depending on the insert size, this study measured forces acting on conical cutters with different cutter spacings, penetration depths and skew angles using slim and heavy conical cutters. When cutter spacings ranged from 12 to 27 mm, the deviations of mean cutter forces with cutter depths appeared smaller compared to other cutter spacings. When skew angle is $0^{\circ}$, the optimal S/d ratio was obtained in the range of 4 to 4.5 for which specific energy of cutting was minimized. It were usually found in the range of 1 to 5. However, when skew angle is $6^{\circ}$, the optimal S/d ratio was obtained in the range of 1 to 3. The simple comparison results shows that the performance of slim cutter was superior to that of heavy cutter, but the use of heavy cutter can be effective, considering the cutter consumption and cutter damage when the strength of the ground is high enough.