• 설비공학논문집
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• 제14권8호
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• pp.676-682
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• 2002

This paper has been made to investigate the thermal performance characteristics for the several types of heat sinks such as extruded heat sink, aluminum foam heat sink, layered heat sink. The various types heat sinks are prepared and tested for natural convection as well as forced convection. The experimental results for natural convection are compared to those for three types of heat sink so that the appropriate heat sink can be designed or chosen according to the heating conditions. The overall heat transfer performances for layered heat sink, extruded heat sink and aluminum foam heat sink are almost comparable to those under natural convection and forced convection. The forced convection of layered heat sink become 1.2 times as high as those of extruded heat sink, and the forced convection of extruded heat sink become 1.2 times as high as those of aluminum foam heat sink. This study shows that bar height, bar distance and number of bar for layered heat sink are important parameters, which have a serious influence on thermal performance for layered heat sinks.

• ETRI Journal
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• 제33권2호
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• pp.251-258
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• 2011

Applying face alignment after face detection exerts a heavy influence on face recognition. Many researchers have recently investigated face alignment using databases collected from images taken at close distances and with low magnification. However, in the cases of home-service robots, captured images generally are of low resolution and low quality. Therefore, previous face alignment research, such as eye detection, is not appropriate for robot environments. The main purpose of this paper is to provide a new and effective approach in the alignment of small and blurred faces. We propose a face alignment method using the confidence value of Real-AdaBoost with a modified census transform feature. We also evaluate the face recognition system to compare the proposed face alignment module with those of other systems. Experimental results show that the proposed method has a high recognition rate, higher than face alignment methods using a manually-marked eye position.

• ETRI Journal
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• 제31권2호
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• pp.182-192
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• 2009

Rain attenuation and intercell interference are two crucial factors in the performance of broadband wireless access networks such as local multipoint distribution systems (LMDS) operating at frequencies above 20 GHz. Power control can enhance the performance of downlink CDMA-based LMDS systems by reducing intercell interference under clear sky conditions; however, it may damage system performance under rainy conditions. To ensure robust operation under both clear sky and rainy conditions, we propose a novel power-control scheme which applies an adaptive neuro-fuzzy inference system (ANFIS) for downlink CDMA-based LMDS systems. In the proposed system, the rain rate and the number of users are two inputs of the fuzzy inference system, and output is defined as channel quality, which is applied in the power control scheme to adjust the power control region. Moreover, ITU-R P.530 is employed to estimate the rain attenuation. The influence of the rain rate and the number of users on the distance-based power control (DBPC) scheme is included in the simulation model as the training database. Simulation results indicate that the proposed scheme improves the throughput of the DBPC scheme.

• 국제물리치료학회지
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• 제11권3호
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• pp.2102-2106
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• 2020

Background: Static hamstring stretching exercises have been widely used to improve flexibility of the hamstring muscles. However, few studies have examined the influence of standing static hamstring stretching (e.g., jack-knife stretching) on movements of the lumbopelvic-hip complex. Objectives: To examine the short-term effects of jack-knife stretching on movements of the lumbopelvic-hip complex. Design: Case series. Methods: Fourteen participants with hamstring tightness (8 male, 6 female) were recruited. Participants performed jack-knife stretching for 150 s. Before and after stretching, participants performed the finger-to-floor distance (FFD), sit and reach (SRT), active knee extension (AKE), passive straight leg raising (PSLA), and active straight leg raising (ASLR) tests as well as pelvic tilt while standing to identify the effects of stretching. Results: There were significant improvements in the FFD, SRT, AKE, PSLA, and ASLR tests after stretching. However, pelvic tilt angle while standing did not significantly change. Conclusion: Jack-knife stretching can be a useful exercise to improve flexibility of the hamstring muscles, but not pelvic alignment while standing.

• 제어로봇시스템학회논문지
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• 제8권11호
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• pp.954-962
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• 2002

In a park or street, we can see many people jogging or walking with their dogs tracking their masters. In this study, an entertainment robot that imitates a dog's behavior is created. The robot's task is tracking a moving target that is recognized as the master. In order to design the robot, the ecological approach. in which the robot's goals and surroundings heavily influence its design, is used. A three-wheel type locomotion system is designed as the robot's physical structure which can follow a human jogging in outdoor space like a park. A sensor system which can detect the position of a master for the robot in the outdoor space, is developed. This sensor system consists of a signal transmitter which is at the hand of a master and some sensors which are mounted on the robot. The transmitter emits RF(radio frequency) and ultrasonic signals and the sensors detect the direction and distance from the robot to the transmitter by using the received signals. For the control architecture of the robot, a purely reactive behavior-based method is used in order to increase speed of response. The developed robot is evaluated through experiments conducted in indoor and outdoor environments.

• 천문학회보
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• 제37권2호
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• pp.70.1-70.1
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• 2012

We investigate 53 late-type galaxies in Virgo to get better understanding galaxy evolution driven by environmental effects in the cluster. The goal is to study how galaxies are strongly affected gravitationally by their surroundings and/or how interstellar medium (ISM) of galaxies changes through the interaction with intracluster medium (ICM). To quantify these, a variety of diagnostic methods have been introduced. Our diagnostics have two different perspectives. First, we have carefully examined the morphological and kinematical properties of individual galaxies using high resolution HI images and compared with multi-wavelength data. Based on the visual inspection, we have identified signatures of the interactions with other galaxies or the ICM. Second, we have quantified influence of local environments of individual galaxies using X-ray data and optical catalog of the cluster. By combining all the diagnostics, we have identified the environmental effect(s) at work on individual galaxies. We also probe the environmental processes as a function of the cluster centric distance. Various gravitational interactions are found throughout the cluster, while the ICM-ISM interaction is mainly dominant near the cluster center. However, we find some evidence that galaxies start losing their gas already in the low density outskirts of the cluster.

• 한국시뮬레이션학회논문지
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• 제16권1호
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• pp.39-47
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• 2007

도심지내 이동시 지점 간 속도는 시간대와 해당 지점에 따라 차이가 발생한다. 또한 두 지점 사이에는 수많은 신호대기와 병목 구간 등으로 인한 지체가 빈번히 발생한다. 이러한 지체 시간은 차량 경로를 계획함에 있어서 상당히 중요한 요소로 작용한다. 하지만 기존 차량 경로 문제 중 지점 간 이동 거리와 이동 시간에 초점을 맞춘 연구에서 지점 이동시 발생하는 지체에 대해서는 연구가 활발히 진행되지 않았다. 이에 본 연구에서는 지체 시간을 고려한 현실적인 차량 경로 문제에 접근한다. 이를 위해 신호 대기 간 발생하는 지체 시간과 병목 구간에서 발생하는 지체 시간을 추정하는 모델을 제시한다. 추정된 결과를 반영한 최적 차량 경로를 도출하여 지체 시간을 고려하지 않은 경로와 결과를 비교해 봄으로써 본 연구에서 제시하고 있는 방법이 우수하며 효율적임을 제시한다.

• 대한기계학회논문집
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• 제13권4호
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• pp.689-696
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• 1989

본 실험에서는 종래와는 달리 먼저 입출구 부분에서 입자분포 측정장치를 이용하여 실험함으로써 여러 가지 입자크기에 대하여 동시에 효율을 구할 수 있는 장치를 구성하고 앞에서 열거한 여러 가지 실험인자중 레이놀즈수와 S/W를 변화시키면 서 일단 슬릿 임팩터(one-stage slit impactor)의 효율을 .root.Stk에 따라 구하여 일단 임팩터 뿐만 아니라 다단 임팩터(multistage impactor)에 대한 설계기초자료를 마련하 고자 한다.

• The Korean Journal of Ecology
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• 제26권1호
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• pp.29-33
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• 2003

도로의 건설로 인해 산림생태계의 단절이 발생한 백두대간의 진부령, 진고개, 삽당령, 백복령, 화방재, 이화령, 덕산재, 여원재 등 8개 국도 지역에서 번식기 조류군집을 대상으로 2002년 4월부터 6월까지의 기간동안 도로로부터 거리가 다른 지역별 번식기 조류군집의 특성을 파악하였다. 도로로부터 가까운 지역보다 먼지역에서 관찰된 종수와 개체수가 많았다. 또한 길드 구조의 분석 결과 도로의 인접지역이 도로로부터 멀리 떨어져 있는 지역보다 나무구멍 둥지자원과 수관층 먹이자원을 이용하는 조류의 종수와 개체수가 적었다. 이는 도로의 건설로 인해 조류의 서식지 환경이 변화하게 되고 그 결과 조류군집 구조에 영향을 주는 것으로 판단된다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 Asia Navigation Conference
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• pp.71-78
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• 2006

The image of an object obtained by the radar is not corresponding to its true shape, because the image of an object observed by the radar is receiving an influence such as multiple-reflections and expanded in bearing because of the beam width of a radar. In addition, a radio wave does not hit the entire surface of an object. Therefore, the image of the front side of a ship facing a radar antenna corresponds to its true shape. In this paper, a method to estimate a ship's shape by means of the integration of the front parts of images obtained from radars is proposed. In addition, a matter, which is observation error of each radar, in using multi-radars, and the process included in the proposed method for solving the matter, are described. As a result of the experiment, the accuracy of about 3 degrees in ship's heading and about 14 meters in length and about 9 meters in beam was obtained.