• Earthquakes and Structures
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• 제7권5호
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• pp.753-777
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• 2014

This study investigates the behavior of precast concrete cantilever wall systems with new vertical connections under cyclic loading. C-type steel connections for PC wall systems are proposed for the transfer of bending moments between walls in the vertical direction, whereas a shear key in the center of the wall is prepared to transfer shear forces by bearing pressure. The proposed connections are assembled easily because the directions of the slots are different at the edges of the walls. Structural performance characteristics such as the strength, ductility, and failure modes of test specimens were investigated. The longitudinal reinforcing steel bars, which are connected to the C-type connections, yielded first. Ultimate deformation was terminated owing to premature failure of the connections. The strength and deformation obtained from the cross-sectional analysis were generally similar to experimental data.

• 콘크리트학회논문집
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• 제22권4호
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• pp.461-472
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• 2010

이 논문은 새로운 수직 접합부를 가진 프리캐스트 벽체의 거동에 관한 연구이다. PC 벽체를 이용한 리모델링 건설을 위해서는 효율적이고 경제적인 조립 방법이 필요하다. C형 수직 접합부를 가진 PC 벽체 시스템은 수직방향의 벽체 사이의 휨모멘트를 전달하도록 하고, 반면에 벽체 중심에 있는 전단키는 전단력을 부담하도록 하였다. 제안된 수직 접합부는 벽체 단부에 서로 다른 방향의 슬롯 때문에 조립이 용이하다. 횡력을 받는 일자형 PC 벽체 시스템을 강성, 강도 그리고 파괴 모드에 대해 기존의 RC 벽체와 비교하였으며, 힘과 처짐과의 관계와 접합부의 조기파괴에 관해 알아보았다. 실험 결과 벽체 단부에 설치된 수직 철근이 먼저 항복하였고, 최종 변형은 접합부의 조기 파괴에 의해 결정되었다. 그리고 벽체에서 효과적인 전단력 전달을 위한 대각선 철근은 그다지 효과적이지 않았다. 단면 해석을 통해 구한 강도와 변형은 실험값과 대체로 일치하였다. 특히, 개폐거동에 의한 변형이 가장 큰 비율을 차지하였다.

• 대한기계학회논문집B
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• 제24권6호
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• pp.870-879
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• 2000

An experimental investigation is conducted to improve a slot film cooling system which can be used for the cooling of gas turbine combustor liner. The tangential slots are constructed of discrete holes with different injection types which are the parallel, vertical, and combined to the slot lip. The investigation is focused on the coolant supply systems of normal-, parallel-, and counter-flow paths to the mainstream direction. A naphthalene sublimation technique has been employed to measure the local heat/mass transfer coefficients in a slot with various injection types and coolant feeding directions. The velocity distributions at the exit of slot lip for the parallel and vertical injection types are fairly uniform with mild periodical patterns with respect to the hole positions. However, the combined injection type increases the nonuniformity of flow distribution with the period equaling twice that of hole-to-hole pitch due to splitting and merging of the ejected flows. The secondary flow at the lip exit has uniform velocity distributions for the parallel and vertical injection types, which are similar to the results of a two-dimensional slot injection. In the results of local heat/mass transfer coefficient, the best cooling performance inside the slot is obtained with the vertical injection type among the three different injection types due to the effect of jet impingement. The lateral distributions of Sh with the parallel- and counter-flow paths are more uniform than the normal flow path. The averaged Sh with the injection holes are $2{\sim}5$ times higher than that of a smooth two-dimensional slot path.

• 대한치과교정학회지
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• 제50권1호
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• pp.26-32
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• 2020

Objective: The Heat Induction Typodont System (HITS), used in some recent studies, has a distinct advantage over previous tooth movement simulation methods. This study aimed to compare inclination and vertical changes between the single-wire and double-wire techniques during en masse retraction with different lengths of lever arms in lingual orthodontics using an upgraded version of the HITS. Methods: Duet lingual brackets, which have two main slots, were used in this study. Forty samples were divided into four groups according to the length of the lever arm (3-mm or 6-mm hook) and the retraction wire (single-wire or double-wire). Four millimeters of en masse retraction was performed using lingual appliances. Thereafter, 3-dimensional-scanned images of the typodont were analyzed to measure inclination and vertical changes of the anterior teeth. Results: Incisor inclination presented more changes in the single-wire groups than in the double-wire groups. However, canine inclination did not differ between these groups. Regarding vertical changes, only the lateral incisors in the single-wire groups presented significantly larger values than did those in the double-wire groups. Combining the effect of hook lengths, among the four groups, the single-wire group with the 3-mm hook had the highest value, while the double-wire group with the 6-mm hook showed the least decrease in crown inclination and extrusion. Conclusions: The double-wire technique with an extended lever arm provided advantages over the single-wire technique with the same lever arm length in preventing torque loss and extrusion of the anterior teeth during en masse retraction in lingual orthodontics.

• 한국항행학회논문지
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• 제27권4호
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• pp.463-468
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• 2023

본 논문에서는 Pin 다이오드와 결함접지구조를 이용하여 2 개의 편파(수직 편파, 우현 편파)를 전환하여 사용할 수 있는 이중편파 재구성 패치 배열 안테나를 제안한다. 제안된 안테나는 정사각형 마이크로스트립 패치와 접지면에 2개의 일자형 슬롯을 대각선으로 배치하여 구현된 원형 편파 패치 안테나를 5.8 GHz의 반파장 길이인 25.8 mm 간격으로 3x3 배열하여 설계하였으며 각 안테나의 접지면에 대각선으로 배치된 슬롯에 Pin 다이오드와 커패시터를 연결하여 Pin 다이오드에 직류 전압이 인가에 따른 개방/단락 스위치 동작을 통하여 편파를 전환한다. 설계 결과 수직 편파에서는 11.7 dBi, 우현 편파에서는 11.6 dBic의 이득 특성을 가지며 우현 편파에서의 축비는 1.8 dB, 수직 편파일 때 20.3 dB 를 가지고, 중앙 안테나에서 인접한 안테나의 상호결합 특성을 확인 하였을때 수직 편파에서는 최대 -20.8 dB, 우현 편파에서는 최대 -30.1 dB 이다.

• Architectural research
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• 제10권1호
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• pp.33-39
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• 2008

Condensation has mainly occurred in corridor type apartment door which is exposed to the outside air and is made of steel, which has high thermal conductivity. As a result, the total costs of repair have increased with the number of disputes with residents. In this study, therefore, we investigate materials and construction methods used in apartment door, perform a computer simulation to find out possible improvements, and then suggest the dew point to prevent the occurrence of condensation throughout simulation. The results indicate that the temperature that condensation does not occur is $15.4^{\circ}C$, and the optimum method of achieving this dew point is shown to be a door frame system including a large vertical slot to decrease the area of thermal conduction between the outer and inner portions of the door frame. Mock-up tests show that the surface temperature of the door frame was higher than the dew point, and the system can withstand severe cold conditions of $-20^{\circ}C$. In application test, the surface temperature of door frame with vertical slots is $5.9^{\circ}C$in average, which is higher than the existing door frame. Furthermore, in the temperature distribution of the surrounding door measured with infrared ray camera, the existing door shows the high temperature distribution indicating lack of insulation, but the improved door shows the low temperature distribution indicating higher insulation.

• 산업공학
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• 제15권1호
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• pp.64-72
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• 2002

Broaching machine is widely used for machining inner shaped slots in the work-pieces, and provides vertical motion (usually hydraulically powered) between tool and work-piece. In this study, we modelled the tool life process and investigated economic tool life of broaching machine. Tool life process is divided into wear-process and succeeding failure process. Wear process is defined as machining wear and failure process as 'chipping' occurred by random shock. We modelled wear process as linear regression function for products amounts and assumed failure process as Poisson process. Economic tool life is defined as the number of lots which minimizes average tool related cost per lot and analyzed by using age replacement policy technique. As tool-related cost factors, we consider tool replacement cost, tool maintenance cost and quality costs of products. The results of this study can be applied to analyze life process of general machining tools.

• 한국위성정보통신학회논문지
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• 제2권2호
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• pp.10-15
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• 2007

위성방송수신 및 위성 양방향 인터넷, VSAT 등의 위성통신서비스를 차량 이동 시에도 이용할 수 있기 위해서는 차량에 탑재하기 용이하도록 소형이며 높이가 낮은 안테나 구조가 요구된다. 또한 중위도 지역에서 평면 안테나 상태로 45도 빔틸트 특성을 갖고, Ku 밴드의 위성통신용으로 충분한 고이득을 얻기 위해, 빔폭이 좁고 사이드로브가 적으며 저손실 구조의 배열안테나 개발이 필요하다. 본 논문에서는 이러한 성능을 만족시키기 위해, 진행파형 누설파 모드를 기초로 한 수직 편파로 동작하는 도파관 종방향 슬롯 배열안테나를 제안하였다. 16개 누설파 소자의 배열안테나 이득은 30 dBi 이었으며, 빔폭은 4.9도, 사이드로브 레벨은 -20 dB 이하, 중심주파수에서 빔틸트 각도는 45도를 얻었다. 급전선로는 도파관의 병렬급전 방식으로 설계하여 광대역, 저손실 특성을 얻을 수 있었다.

• Computers and Concrete
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• 제20권5호
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• pp.539-544
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• 2017

Shear walls have high stiffness and strength; however, they lack energy dissipation and repairability. In this study, an innovative slotted shear wall featuring vertical slots and steel energy dissipation connectors was developed. The ductility and energy dissipation of the shear wall were improved, while sufficient bearing capacity and structural stiffness were retained. Furthermore, the slotted shear wall does not support vertical forces, and thus it does not have to be arranged continuously along the height of the structure, leading to a much free arrangement of the shear wall. A frame-slotted shear wall structure that combines the conventional frame structure and the innovative shear wall was developed. To investigate the ductility and hysteretic behavior of the slotted shear wall, finite element models of two walls with different steel connectors were built, and pushover and quasi-static analyses were conducted. Numerical analysis results indicated that the deformability and energy dissipation were guaranteed only if the steel connectors yielded before plastic hinges in the wall limbs were formed. Finally, a modified D-value method was proposed to estimate the bearing capacity and stiffness of the slotted shear wall. In this method, the wall limbs are analogous to columns and the connectors are analogous to beams. Results obtained from the modified D-value method were compared with those obtained from the finite element analysis. It was found that the internal force and stiffness estimated with the modified D-value method agreed well with those obtained from the finite element analysis.

• 한국통신학회논문지
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• 제40권7호
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• pp.1369-1376
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• 2015

센서장비에 장착되는 무선통신 모듈은 선내 통합유무선 네트워크와의 원활한 연결을 위하여 무선 게이트웨이 기능을 수행하는 Bridge(브릿지)를 통한 데이터 전송방식이 필요하다. 본 논문에서는 선박 및 실내 끊김없는 N-스크린 서비스를 위한 무선 통신 MAC 구조로서, WiMedia Distributed-MAC(D-MAC) 프로토콜을 적용하고, 끊김없는 D-MAC 프로토콜에서 P2P(Point to point) 스트리밍이 가능한 OSMU(One Source Multi Use) N-스크린 서비스를 제공하기 위해, 동적 Threshold 기반 멀티캐스트 기술을 제안하고 성능을 분석하였다. 이를 위해 새로운 Hard/Soft Vertical Region(HVR-SVR) 기반 타임 슬롯 할당 기술과 Multicast 자원 예약기술을 결합하였다. 시뮬레이션 결과를 통해 동적 Threshold 기반 멀티캐스트 기술은 다양한 서비스 시간 간격 요구를 갖는 실시간 N-스크린 데이터 전송에 있어, 멀티캐스트 및 유니캐스트 전송 DRP 예약 구간을 확장하고 수율을 향상시키는 효과를 나타내었다.