• The KIPS Transactions:PartA
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• v.9A no.2
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• pp.197-206
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• 2002

Many researchers have been interested in the optimization of parallel programs through the latency hiding by overlapping the communication with the computation. We ana1yzed overlapping effects in the circular shift communication which is one of the collective communications being frequently used In many data parallel programs. We measured the time which can be possibly overlapped and the time which cannot be overlapped in over all circular shift communication period on an Ethernet switch-based clustered system. The result from each platform nay be used for the input of optimizing compilers. The previous performance models usually have two kinds of drawbacks one is only based on point-to-point communication, so it is not appropriate for analyzing the overall effects of collective communications. The other provides the performance of collective communication, but no overlapping effect. In this paper we extended the previous models and analyzed the experimental results of the extended model.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.3
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• pp.291-299
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• 2010

Aspect-ratio-based numerical analysis is carried out to investigate the air-side convective heat transfer characteristics in compact heat exchangers with circular tubes and flat tubes-plate fins. The RNG $k-{\varepsilon}$ model is adopted for turbulence analysis. The numerical analysis is carried out for aspect ratios ranging from 3.06 to 5.44 and for Reynolds numbers ranging from 1,000 to 10,000. The calculated results indicate a correlation between the friction factor and Colburn j factor in the compact heat exchanger system for the range of aspect ratios under consideration. The results obtained for circular tubes and flat tubes-plate fins in this study can be utilized to realize the optimal design of an air conditioning system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.4
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• pp.628-635
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• 1999

At center frequency of 11.85 GHz, wideband left-handed circularly polarized microstrip array antenna is designed with the method of sequential ratation based on $2\times2$ radiation elements($0^{\circ}$, $45^{\circ}$, $90^{\circ}$, $135^{\circ}$ phase delay). Its return loss, axial ratio bandwidth, radration pattern, and gain are compared with those adopting sequential rotation based on $1\times2$ radiation elements($0^{\circ}$, $90^{\circ}$, $180^{\circ}$, $270^{\circ}$phase delay). The $8\times8$ array is manufactured and measured. The results show that 10 dB return loss bandwidth is 10.51~12.74GHz(18.82%) which is 1.57 times wider than the case using $1\times2$ sequential rotation method, 3 dB axial ratio bandwidth is 11.43~12.5 GHz(9.03%) which is 1.25 times as wide as that using $1\times2$ sequential rotation method and the antennal gain is 25.4 dB. The results of mesurements are almost similar to those of simulation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.274-284
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• 1991

Mean flows and Reynolds stresses through circular and elliptic wire-mesh screens in the wind tunnel are measured by using the hot-wire system, and flow structures are investigated. Flow in the core of the wake are nearly uniform and the shear layer is developed along the edge of the screen The turbulent kinetic energy in the core decreases at the fast rate. However turbulence components are not in local equilibrium in the shear layer. The shear layer of the circular screen develops outward according to the radial mean motion. On the other hand, 3-dimensional transverse mean motion was turned to the main mechanism for the elliptic shape of the wake to be circular at the downstream.

• Magazine of the Korea Concrete Institute
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• v.3 no.4
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• pp.133-142
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• 1991

When the behavior of a prototype concrete structure is studied through small-scale model experiments, it is necessary to reproduce all significant physical characteristics on either an one-to-one basis or a specific similitude relationship. Any distortion of similitude must be understood and its effect must be predictable. This paper focuses on improved physical modeling techniques for small-scale reinforced concrete structures. Particular emphasis is placed on the development of a model concrete mix to accurately model the important properties of full-scale prototype concrete. Four types of model reinforcement with different bond characteristics are also studied by testing twenty simple beams. The information obtained will be of immediate use to engineers contemplating small-scale modeling of reinforced concrete structures.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.4
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• pp.386-392
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• 2002

This paper presents a basic characteristics of 4-element circular array dipole antennas for 4-sector beam steering. The coupled integral equations for the unknown current distributions on dipole elements are derived and solved by applying Galerkin's method of moments. The parasitic elements have been used to increase the directional gain and the beam is steered electronically either by sswitching between the parasitic elements or switching the position of the active element. The parasitic elements are switched short-circuited or open-circuited as required to steer a directional beam. In order to verify the theoretical analysis, the radiation pattern was compared with experiments.

• Applied Microscopy
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• v.4 no.1
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• pp.25-33
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• 1974

The origin and the function of cytolysomes were studied in the mesophyll cells and the root-tip cells of Glycine max Merr. and Zea mays L. fixed by paraformaldehyde-glutaraldehyde-$OsO_4$. The cytolysome-like structures were found of three main types of configurations: multivesicular, myelin like (multilamllar) and multitubular. More complex and mixed ones were also observed. The origin of these structures seems to be initiated by invaginations or in holdings of the plasmalemma into the cell interior, and that by aggregation and convolution of endoplasmic reticulum in the cytoplasm. Invagination of the plasmalemma were found of two main types of configurations: concentric whorls of lamellar and multivesicular. The structures were also observed within vacuoles and cytoplasm. Since the structurers are widely distributed in the cells and are greatly varied in sizes and shapes. These structures originate from the plasmalemma and the cytoplasm subsequently protrudes into the vacuole, and that seem to play an important role on the formation of the autophagic vacuoles. The possible function and fate of these structures are discussed.

• Korean Journal of Heritage: History & Science
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• v.49 no.1
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• pp.100-119
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• 2016

The concept of "original form" and the principle of "maintaining the original form" take center stage in conservation, management, and promotion of the domestic heritage. Introduced in the 20th century, there were little discussion or deliberation about the concept of "original form" therefore it remains a vague and somewhat abstract notion subject to individual interpretation. Without a specified practical meaning, "maintaining the original form" became the fundamental principle for heritage conservation and management in the 1999 version of the Cultural Heritage Protection Act, engendering difficulties in applying the principle in practice. Conceived as an important first step toward resolving the issues stemming from the indistinct concept of "original form," this paper explores the process through which the concept was introduced to Korea and then established and developed as a legal principle for heritage conservation, management, and promotion. While the examination of the related documents and various cases shows that the development of the concept of "original form" has centered on specific periods and architectural styles, this essay explicates that the notion "original form" is commonly used as a term referring to the form at the earliest possible temporality. It also explains that this view emanates from perceiving heritages not as multivalent objects, but as a material object that exclusively carries aesthetic and, more importantly, historical value, and that comes from the history awareness of the times. This essay suggests that the concept "original form" should be reestablished with full consideration of the diverse values of heritage and diverse forms through which heritage can be expressed. After reviewing the feasibility and practicality of the concept a set of concrete guidelines should be presented for application in practice.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.677-680
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• 2001

본 논문에서는 컬러 장치들간에 색을 일치시키기 위하여 휘도 대비와 채도 향상을 고려한 원형 색역 사상(circular shape-based gamut mapping)방법을 제안하였다. 서로 다른 장치들간에 색역을 일치시키기 위해 장치 독립적이고 균등 색 공간인 CIELAB값으로 변환하여 색역 사상을 수행하였다. 인간 시각에 상대적으로 민감한 특성을 가지는 휘도 성분을 JND(just noticeable difference)에 기반해 분할하고, 이를 기점으로 색역을 원의 형태로 나눈다. 이렇게 나뉜 색역은 사상의 방향성을 결정하는 기본 단위로 사용되어, 이들 영역을 기점으로 영역 대 영역별 사상 방법을 사용하였다. 제안한 색역 사상 방법을 모니터와 프린터간에 적용한 결과 보다 선명하고 휘도 대비가 높은 영상을 얻을 수 있었다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.303-307
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• 1998

본 논문에서는 고주파수 대역의 진동 전달 현상을 묘사할 수 있는 원형파를 기본 개념으로 한 레이 추적기법(RTM)을 개발하였다. 2차원 원형파를 묘사할 수 있는 레이튜브 개념을 제안하고, 진동 연성경계에서의 입사파, 전달파, 그리고 반사파가 경계조건을 만족하도록 관계식을 유도하였다. 이를 평판 연속 구조물이 고주파수 진동 전달 해석에 적용하여 보았으며, 유사 해석 기법인 SEA 및 파동 인텐시티해석법(WIA)과의 비교를 수행하여 보았다. 그 결과, SEA에 비하여 이론해와 더 잘 맞는 예측 결과를 관찰할 수 있었으며 WIA와 유사한 결과를 보임을 확인할 수 있었다. 본 논문에서 제안된 RTM은 진동전도해석(VCA)과 같이 지역적 정보를 알 수 있는 장점도 가지고 있으며, 2차원 진동구조물의 고주파수 진동 전달 해석시 기존이 SEA 및 WIA를 대체할 수 있는 기법으로 판단된다.