• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.4
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• pp.308-320
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• 2006

An analytic solution to the mild-slope equation is derived for waves propagating over an axi-symmetric pit. The water depth inside the pit varies in proportion to a power of radial distance from the pit center. The governing equation is transformed into ordinary differential equations by using separation of variables, and the coefficients of the equations are transformed into explicit forms by using Hunt's (1979) approximate solution. Finally, by using the Frobenius series, the analytic solution is derived. Due to the feature of Hunt's equation, the present analytic solution is accurate in shallow and deep waters, while it is less accurate in intermediate depth water. The validity of the analytic solution is demonstrated by comparison with numerical solutions. The analytic solution is also used to examine the effects of pit geometry and relative depth on wave transformation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.423-427
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• 2017

In this paper, an anchor design that improves bonding strength uniformity in the silicon-on-glass (SOG) process is presented. The SOG process is widely used in conjunction with electrode-patterned glass substrates as a standard fabrication process for forming high-aspect-ratio movable silicon microstructures in various types of sensors, including inertial and resonant sensors. In the proposed anchor design, a trench separates the silicon-bonded area and the electrode contact area to prevent irregular bonding caused by the protrusion of the electrode layer beyond the glass surface. This technique can be conveniently adopted to almost all devices fabricated by the SOG process without the necessity of additional processes.

• Journal of Energy Engineering
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• v.11 no.1
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• pp.18-25
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• 2002

One of the most serious concern in nuclear power plant piping maintenance is thickness reduction due to flow-accelerated corrosion (FAC). Since the FAC occurs under specific conditions of pH, dissolved oxygen, temperature, flow velocity, steam quality of the fluid and materials and geometry of the piping, a systematic approach is required for managing the FAC problem. In this study, construction of a secondary piping database, analyzing the FAC rate using the database and predicting the residual life was performed for a domestic CANDU nuclear power plant. Also FAC mechanism and factors affecting FAC were reviewed. By showing a case study on analysis for a pipe line between a separator and a flash tank, a procedure for managing FAC problem is suggested. The procedure proposed in this paper can be widely applied to the secondary piping of other domestic nuclear polder plants.

• Archives of design research
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• v.15 no.4
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• pp.77-86
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• 2002

3D computer applications provide various functions such as modeling, rendering, animation, lighting and so on. Lighting is the core element in that light visualizes shape and develops characteristics of surface. In spatial design, light is the most important factor in deciding color, texture and illumination level which are the basic factors of spatial design. The purpose of this study is to define the characteristics of lighting in digital space provided by the computer, based on the fact that physical space cannot be separated from digital space, and to show how light in the physical realm relates to computer graphics technologies. This study shows there are following characteristics of light in digital space; iconic light, modifiable surface, shadowless light, 2-dimensional perception, and the particulate aspect of light but not the wave aspect of light. Light in physical or digital space is capable of producing a visual sensation. The experimental space can be realized due to the lack of physics. Further study in new illumination procedures are required as computer media expands.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.11
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• pp.941-948
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• 2016

Textile composite materials have been widely applied in aerospace structures due to their various advantages such as high specific stiffnesses and strengths, better out-of-plane performances, impact and delamination resistances, and net shape fabrications. In this paper, a modified geometric model of repeating unit cell (RUC) is suggested based on the Naik's model for 2D plain weave textile composites. The RUC geometry is defined by various parameters. The proposed model considers another parameter which is a gap length between adjacent yarns. The effective stiffnesses are predicted by using the yarn slicing technique and stress averaging technique based on iso-strain assumption. And the stiffnesses of RUC are evaluated by adjusting the gap ratio and verified by comparing with Naik's model and experimental data for 2D plain weave composite specimens.

• Journal of KIISE:Software and Applications
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• v.37 no.1
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• pp.80-84
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• 2010

Tracking hands is an essential technique for hand gesture recognition which is an efficient way in Human Computer Interaction (HCI). Recently, many researchers have focused on hands tracking using a 3D hand model and showed robust tracking results compared to using 2D hand models. In this paper, we propose a novel 3D hand tracking method based on a coupled particle filter. This provides robust and fast tracking results by estimating each part of global hand poses and local finger motions separately and then utilizing the estimated results as a prior for each other. Furthermore, in order to improve the robustness, we apply a multi-cue based method by integrating a color-based area matching method and an edge-based distance matching method. In our experiments, the proposed method showed robust tracking results for complex hand motions in a cluttered background.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.371-374
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• 2012

본 연구는 "사이클론과 관성충돌 및 백필터의 제진원리를 일체화한 고효율 멀티 제진시스템의 최적화 설계를 위한 수치 해석적 연구(I) : 집진기 입구 최적화 설계"에 이은 일련의 연구로서 앞선 연구에서 도출된 사이클론부 하단 벤츄리(Venturi)에서의 강한 하향 기류의 가속에 따른 분진 재비산 가능성에 대한 추가적 검토를 위한 연구이다. 사이클론부를 통과한 기류가 상향 흐름으로 방향을 전환할때 좀 더 가속시켜 빠르게 곡률반경을 형성하여 조대 입자의 분리를 극대화시키기 위한 목적으로 사이클론부 하단을 벤츄리 형상으로 설계하였으나, 유동장 분석 결과 벤츄리를 통과한 처리가스 흐름이 가속되면서 호퍼 하단까지 약 4~5 m/s의 강한 하향 흐름을 형성하고 호퍼 하부의 말단 부근에서 상향 흐름으로 방향 전환을 하고 있는 것으로 예측됨에 따라 설계 의도와는 달리 벤츄리 설치시 호퍼 하단에 포집된 분진의 재비산을 예방하는데는 크게 역할을 하지 못하는 것으로 나타났다.

• Composites Research
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• v.26 no.5
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• pp.279-288
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• 2013

In this paper, the delamination and deformed FSS caused by residual stresses in the Loop type FSS embedded composites and the transmission characteristic changes due to deformation of FSS by residual stresses were studied. FSS may have different electromagnetic characteristics depending on the type of element, design variables, and array. Therefore, design variables of square loop FSS embedded composites structures were determined to obtain the transmission characteristic for X-band (8~12 GHz). Then the design variables of other types of loops (triangular loop and circular loop) were determined based on the dimensions of square loop. Thereafter, the residual stresses and transmission characteristics of FSS embedded composite structures with various single and double loop FSS's, and stacking sequence of composite laminates were compared.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.90-97
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• 2014

In this paper, we have designed the antenna for Korea SAT-5 Satellite Communication which can use Ka band in the earth station. The antenna structure consist of the the dual-offset gregorian reflector that has high gain and efficiency, the corrugated horn that has symmetric radiation patterns and low side lobe levels, the iris polarizer that make circular polarization and the OrthoMode Transducer that separate transmitting and receiving signals. The designed antenna gain is more than 45.7dBi in Tx-band which use LHCP and 42.0dBi in Rx-band which use RHCP. The co-polarized and cross-polarized radiation pattern comply with ITU-R S.580-6 and S.731-1 that are recommended by International Telecommunication Union in the geostationary satellite. The Axial ratio is less than 1.0dB in Tx-band and 1.5dB in Rx-band that meet MIL-STD-188-164A.

• Geotechnical Engineering
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• v.14 no.2
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• pp.31-40
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• 1998

To verify the reinforcing effect of the strips which are inserted in the backfill, but not connected to the face wall, model tests are executed. As the reinforcing effect is expected to reduce the active thrust acting on the retaining wall, test programmes included the measurements of the thrust. As a result. it is ascertained that the active thrusts are reduced by as much as 50%. Besides, efficient arrangement and the optimum length of the strips are verified. And the the number of reinforcing strips are increased, are close to the Rankine's hypothesis.