• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.215-222
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• 2004

Drift design methods using resizing techniques have been presented as a practical drift control methods of high-rise buildings. Most drift design methods using the resizing techniques have adopted the cross-sectional area as the design variables for all structural members in a structure. However, the cross-sectional area is not always governing sectional property for the structural members, but the governing sectional property of each member is dependent on the characteristics of member forces. In this paper, a drift design method using the sectional property related to the governing displacement participation factor as the design variable of each member is presented and applied to the drift design of 20-story steel frame-shear wall system. It can be noted from example test that drift design method considering member characteristics shows similar or somewhat better results in the view point of structural weights and the accuracy of displacement estimation.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.523-523
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• 2013

대기압 제트 플라즈마는 의료산업 및 재료공정, 정수, 기체흐름 제어 등 다양한 분야에 적용을 위한 연구가 활발히 진행되고 있다. 뿐만 아니라 구동 조건에 따라 다양한 방전 모드가 존재하며, 이에 따라 발생된 플라즈마의 광학적 및 전기적 특성도 매우 다르게 나타나기 때문에 과학적으로도 새로운 현상들이 속속 발표되고 있다. 대기압 제트 플라즈마에서 중요한 과학적 현상 중 하나인 스트리머(streamer) 혹은 플라즈마 총알(plasma bullet)은 수-수십 kHz의 저주파 전압으로 구동 시 특정 조건에서 발생하는 현상으로, 최근 들어 시간분해능이 높은 ICCD 카메라를 이용하여 스트리머의 발생 및 전파에 대한 새로운 현상의 발견과 다양한 물리적 이해가 시도되고 있다. 본 연구에서는 헬륨 대기압 제트 플라즈마에 포함된 질소 함유량에 따른 다중 스트리머의 발생 및 기작의 이해를 시도하였다. 구동 전압 및 주파수, 헬륨기체의 유량, 전극 구조 및 간격 등 모든 조건이 동일한 상태에서 질소기체의 함유량을 증가시킬수록 특정 영역에서 스트리머의 개수가 증가하는 것을 관찰되었다. 또한 $N_2{^+}$의 방출광 세기가 헬륨 및 산소 원자의 방출광보다 지배적인 것으로 측정되었으며, 이는 헬륨 플라즈마에서 흔히 나타나는 헬륨 metastable에 의한 질소분자의 페닝 이온화(Penning ionization) 때문이다. 본 연구팀은 페닝 이온화($He^*+N_2{\rightarrow}He+N_2{^+}+e$)로 인해 추가적으로 발생하는 전자가 다중 스트리머 발생에 중요한 역할을 하는 것이라 제안한다. 좀 더 심화적인 분석을 하고자 헬륨-질소 플라즈마에서 주된 여러 가지 반응식을 이용하여 페닝 이온화에 의한 이온화율 및 전자의 직접적인 충돌에 의한 질소, 헬륨의 이온화율의 계산을 수행하여 특정 영역에서 헬륨의 이온화율보다 질소 페닝 이온화율이 더 커지는 것을 확인하였다.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.39.4-40
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• 2009

이 연구의 목적은 고해상도 합성개구레이더 센서를 탑재한 관측위성의 운용요구사항에 맞춰 임무기간 동안 관측 목표지역을 주기적으로 반복하고 지상궤적을 $\pm2km$ 범위 내에서 안정성을 갖도록 유지 조정하는 궤도제어 알고리즘 연구를 수행하는데 있다. 기존에 수행되어 왔던 지상궤적에 대한 오차를 해석적으로 계산하여 궤도를 유지 조정하는 방법이 아닌 기준궤도에 대하여 상대좌표계에서 표현된 위성의 실제 접촉궤도를 기준궤도와 직접적으로 비교하여 목표궤적을 유지 조정하는 알고리즘을 연구하였다. 이를 위해 첫째, 고해상도 관측위성의 운용요구사항을 만족하는 계획된 목표궤도인 기준궤도를 설계하였다. 기본적으로 기준궤도는 임무 설계 시 완전한 주기성이 고려된 최대한 실제에 가까운 궤도이기 때문에 지구중력장 모델만을 고려하여 간략하게 설계하였다. 둘째, 실제의 인공위성의 궤도는 계획된 기준궤도를 유지해야 하지만 시간에 따라 섭동력의 영향을 받아 계획된 궤도로부터 벗어나게 된다. 기준궤도로부터 실제궤도가 얼마나 벗어나는지에 대한 정량적 분석을 위해 지구 중력장, 달-태양 중력, 대기저항력, 태양복사압, 조석력 등과 같은 다양한 섭동력의 영향에 대한 분석을 수행하였다. 셋째, 반경방향(radial), 진행방향(along-track), 교차방향(cross-track)의 세 방향의 성분으로 구성된 우주공간오차(Space Error) 개념을 적용하여, 투영된 지상궤적에 상응하는 오차를 계산하는 것 보다 안정적으로 오차를 계산하였다. 또한 운용요구사항에 따라 허용된 범위 내에서 궤도를 유지하기 위해 GVE(Gauss Variation Equation)을 이용한 궤도조정을 수행하였다. 섭동력의 분석 결과로부터 지구대기저항력, 달-태양 중력으로 인해 가장 두드러지는 장반경과 궤도이심률의 변화를 조정하기 위해, 임무에 사용되는 추력기의 연료 효율을 고려하여 동결궤도가 유지될 수 있는 최적의 위도이각에서 In-plane에 대한 궤도조정만을 수행하여 장반경과 이심률을 동시에 조정하였다. 지구대기와 태양활동의 영향으로 시간에 따른 장반경의 변화율에 따라 궤도조정 주기를 가지는 것을 알 수 있었고, 이 변화율 때문에 생기는 우주공간오차의 증가를 보정하여 위성의 지상궤적을 목표범위 안에서 유지할 수 있었다.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.6
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• pp.814-819
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• 2010

This paper is presented to study the error minimization of angular velocity for AGV(autonomous ground vehicle). The error minimization of angular velocity is related to localization technique which is the most important technique for autonomous vehicle. Accelerometer, yaw gyro and electronic compass have been used to measure angular velocity. And methods for error minimization of angular velocity have been actively studied through probabilistic methods and sensor fusion for AGVs. However, those sensors still occure accumulated error by mathematical error, system characters of each sensor, and computational cost are increased greatly when several sensor are used to correct accumulated error. Therefore, this paper studies about error minimization of angular velocity that just uses encoder and gyro. To experiment, we use autonomous vehicle which is made by ourselves. In experimental result, we verified that the localization error of proposed method has even less than the localization errors which we just used encoder and gyro respectively.

• Spatial Information Research
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• v.16 no.1
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• pp.51-64
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• 2008

Recently, development and research of u-City established the ubiquitous environment which can be anytime, anywhere computing or network, has been much highlighted. Thus, current urban facilities should be managed by ubiquitous concept, and monitored location and status information in a real-time manner, and controled if necessary. In order to be establish in the purpose of management, indirect mapping through id-tag is better than facility management directly. For instance, RFID, UCODE, UFID. In this paper, we propose that represent facility object through UOID(Unique Object IDentification). UOID comprises three parts; 1) sensing object, 2) facility object, 3) cell object consists of facilities. and Life cycle management system in UOID, and network system connected with internet is proposed. We wish that proposed UOID and network system mange u-City facilities effectively, and also provide ubiquitous service to the citizen, one of the integrate service of u-City platform.

• Journal of the Korea Convergence Society
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• v.8 no.7
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• pp.1-6
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• 2017

This paper presents the design of a frequency measurement device using ADC, EP2AGX FPGA and STM32 processor to accurately measure the frequency of a broadband high frequency signal. The ADC device used in this paper has a sampling frequency of 250 MSPS and a processing frequency bandwidth of 100 MHz. Due to its high sampling frequency, it is difficult to process in ordinary computers or processors, so we implemented the frequency measurement algorithm using the Altra EP2AGX FPGA. The measured frequency is sent to the direction detection controller in real time and fused with the phase signal to calculate the incident azimuth angle of the high frequency signal. The designed frequency measurement device is about 0.2 Mhz in frequency measurement error and 30% less than Anaren DFD-x, which is considered to contribute greatly to the design of radio monitoring and direction detection device.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.359-366
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• 2016

The normal tissue in radiation therapy, to minimize radiation, it is most important to maximize local tumor control rates in intensive research the exact dose to the tumor sites. Therefore, the initial, therapist accuracy of detecting movement of the patient fatigue therapist has been a problem that is weighted down directly. Also, by using a web camera, a difference value between the image to be updated to the reference image is calculated, if the result exceeds the reference value, using the system for determining the motion has occurred. However, this system, it is not possible to quantitatively analyze the movement of the patient, the background is changed when moving the treatment bed in the co-therapeutic device was not able to sift the patient. In this paper, using a alpah(${\alpha}$) filter index is an attempt to solve these limitations points, quantifies the movement of the patient, by separating a background image of the patient and treatment environment, and movement of the patient during treatment It senses only, it was possible to reduce the problems due to patient movement.

• Journal of Navigation and Port Research
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• v.33 no.5
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• pp.303-308
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• 2009

Recently, unmanned systems have been studied and developed in various areas including aircrafts, automobiles and vessels. In addition, many researches about unmanned systems in Korea have been studying actively with the advancement of IT However, it is not satisfied with the result of the researches and developments. Bemuse of the reason we've here tried to make a very small USV which is a barge type. We applied the Great circle navigation calculation based on GPS to the autonomous navigation algorithm and used the LabVIEW 8.2 developed by NI corp. for programming The engine and rudder were controlled by pulse width modulation method. The engine system was composed of the DC motor and ESC(Electronic Speed Controller). It was also applied by the direct cooling system using DC motor pump. A very small USV was designed and made by ourself and it was verified the effectiveness of autonomous navigation algorithm through the tests at the sea.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.12
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• pp.2839-2846
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• 2014

New VHF band for use in VDE is determined by WRC-12 due to the overload of AIS VDL, and the system characteristics of the VDE is recommended as ITU-R M. 1842-1. CS-TDMA, a multiple access method of AIS class B, is recommended as that of the VDE. It is inefficient for CS-TDMA just applying the report interval used in AIS class B to transmit high speed data with higher payload in the aspect of efficiency. In this paper, a simulation is executed in order to determine adequate report interval according to the number of active ships that affects directly network traffic. To this end, the performance of CS-TDMA, which includes the number of received packets, reception success rate, channel utilization, and collision rate, is investigated via a simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.673-675
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• 2015

In recent years, communication between objects is made possible due to the development of IoT(Internet of Things) to the specified business strategy of major countries around the world. However, the standard for representing information of the device is difficult not been set the communication between the devices with different platforms. This paper shows the Conventional people instrument using the method and the simple sensor to the command directly to the machine control system and the information of the devices utilizing different Socialization expression language, XML Schema, information on the job, relationship information of the equipment and devices Machine Socialization proposes a scheme and use them to propose a device management system for managing devices.