• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.1
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• pp.42-48
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• 2011

In this paper, a passive load-pull using a GaN HEMT (Gallium Nitride High Electron Mobility Transistor) bare-chip in X-band is presented. To obtain operation conditions that characteristic change by self-heating was minimized, pulsed drain bias voltage and pulsed-RF signal is employed. An accuracy impedance matching circuits considered parasitic components such as wire-bonding effect at the boundary of the drain is accomplished through the use of a electro-magnetic simulation and a circuit simulation. The microstrip line length-tunable matching circuit is employed to adjust the impedance. The measured maximum output power and drain efficiency of the pulsed load-pull are 42.46 dBm and 58.7%, respectively, across the 8.5-9.2 GHz band.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.6
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• pp.981-987
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• 2017

Jeju Island is a volcanic island which has a large permeability. Groundwater is a major water resources and its proper management is essential. Especially, there is a multilevel restriction due to the groundwater level decline during a drought period to protect sea water intrusion. Preliminary countermeasure using long-term groundwater level prediction is necessary to use agricultural groundwater properly. For this purpose, the monthly groundwater level prediction technique by Artificial Neural Network model was developed and applied to the representative monitoring wells. The monthly prediction model showed excellent results for training and test periods. The continuous groundwater level prediction model also developed, which used the monthly forecasted values adaptively as input data. The characteristics of groundwater declines were analyzed under extreme cases without precipitation for several months.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.1
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• pp.121-128
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• 2017

In this paper, we propose a dual-channel acoustic event detection (AED) method using nonnegative tensor factorization (NTF) and hidden Markov model (HMM) in order to improve detection accuracy of AED in multisource environments. The proposed method first detects multiple acoustic events by utilizing channel gains obtained from the NTF technique applied to dual-channel input signals. After that, an HMM-based likelihood ratio test is carried out to verify the detected events by using channel gains. The detection accuracy of the proposed method is measured by F-measures under 9 different multisource conditions. Then, it is also compared with those of conventional AED methods such as Gaussian mixture model and nonnegative matrix factorization. It is shown from the experiments that the proposed method outperforms the convectional methods under all the multisource conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2131-2141
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• 2015

In this paper, we analyze ADC effect in IBFD system. Also, we design IBFD system with ADC effect, and evaluate BER performance of the system according to power of self-interference. Firstly, we describe a fundamentals of general IBFD system. And then we calculate and analyze characteristics of desired signal before and after ADC when residual self-interference is added to desired signal after RF cancellation. In this calculation, we have confirm some conditions for selection of # of ADC bit. Finally, we design IBFD system with ADC effect, and evaluate BER performance of the system by using Simulink simulation tool. As simulation results, we have confirmed that when power of residual self-interference is high before ADC, IBFD system must use high-bit ADC for decreasing quantization step. Also, we have confirmed that quantization step should be lower than one-third of amplitude of desired signal for effective communication with good performance.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.255-255
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• 2015

국제핵융합실험로(ITER)의 3대 목표 중 하나는 핵융합로 개발을 위한 삼중수소증식블랑켓 개념을 시험하고 검증하는 것이며, 이를 위해 시험증식블랑켓(TBM, Test Blanket Module) 프로그램을 마련, 각국이 참여할 수 있도록 하고 있다. 한국도 2012년 국가핵융합위원회 결정에 따라, EU, 일본, 중국, 인도와 함께 TBM 프로그램에 참여하고 있으며, 2021년 설치를 목표로 헬륨냉각 고체증식재 개념의 HCCR (Helilum Cooled Ceramic Reflector) TBM을 설계, 개발하고 있다. 한국형 TBM은 총 4개의 서브모듈과 하나의 후벽(Back Manifold, BM) 으로 구성되며, 각 서브모듈은 플라즈마와 대면하는 일차벽(First Wall, FW), 증식재와 증배재, 반사재를 담고 있는 증식영역(Breeding Zong, BZ), 냉각재 매니폴드 및 구조물 역할을 하는 측벽(Side Wall, SW) 등의 기능부품으로 구성되어 있다. 냉각재는 8 MPa, $300-500^{\circ}C$의 고온고압헬륨을 사용하고, Li2SiO4 혹은 Li2TiO4 형태의 Li 세라믹 증식재를 사용하며, 중성자 증배를 위해 Be 증배재 및 흑연 반사재를 사용한다 [1-3]. 2015년 2월 개념설계검토(CDR, Conceptual Design Review)를 위해, TBM-shield를 포함한 TBM-set 설계가 완료되었으며, 열수력, 구조, 지진, 전자기, 복합하중에 대한 평가가 진행되었다. 본 논문에서는 이 중 H/He-phase에 시험될 EM-TBM과 D-T phase에 시험될 INT-TBM에 대한 열수력 성능 결과를 소개하였다[5]. 각각의 열부하 조건은 0.17과 $0.3MW/m^2$이며, 중성자 조사는 D-T phase 에서만 고려되었다. 구조재 및 사용된 기능소재별 온도 요건을 정의하고, 성능해석 결과와 비교하였으며, 이를 통해 모든 온도 요건을 만족함을 최종 확인하였다. 이러한 온도 분포는 열응력 평가를 위해 구조해석 입력자료로 활용되었다.

• Journal of Korea Multimedia Society
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• v.12 no.7
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• pp.1006-1015
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• 2009

This paper developed FRESH(Face image REcognition System for intelligent Home), proposed by Hopkins, which was to recognize the face of family members applying for HTM system that integrates a principal movement of human brain's neocortex with computers. For the purpose of confirming a result of the works, we took real photographs of both clear and distorted images, but the result produced higher accuracy about the distorted images providing by a real environment as well as clear images. In addition, the existing studies were focused on the recognition of facial zone that it was difficult to adapt for System for intelligent home. However, this thesis developed a system suitable for intelligent home which corresponds a facial image to his or her name.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.2
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• pp.41-47
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• 1999

In this paper, we report 3D-simulations of a plasma etching process by employing cell-removal algorithm takes into account the mask shadow effect os well as spillover errors. The developed simulator haas an input interface to take not only an analytic form but a Monte Carlo distribution of the ions. The graphic user interface(GUI) was also built into the simulator for UNIX environment. To demonstrate the capability of 3D-SURFILER(SURface proFILER), we have simulated for a typical contact hole structure with 36,000($30{\times}40{\times}30$) cells, which takes about 20 minutes with 10 Mbytes memory on sun ultra sparc 1. as an exemplary case, we calculated the etch profile during the reactive ion etching(RIE) of a contact hole wherein the aspect ratio is 1.57. Furthermore, we also simulated the dependence of a damage parameter and the evolution of topography as a function of the chamber pressure and the incident ion flux.

• Journal of the Korea Society of Computer and Information
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• v.10 no.6 s.38
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• pp.1-8
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• 2005

Facial analysis is used in many applications like face recognition systems, human-computer interface through head movements or facial expressions, model based coding, or virtual reality. In all these applications a very precise extraction of facial feature points are necessary. In this paper we presents a method for automatic extraction of the facial features Points such as mouth corners, eye corners, eyebrow corners. First, face region is detected by AdaBoost-based object detection algorithm. Then a combination of three kinds of feature energy for facial features are computed; valley energy, intensity energy and edge energy. After feature area are detected by searching horizontal rectangles which has high feature energy. Finally, a corner detection algorithm is applied on the end region of each feature area. Because we integrate three feature energy and the suggested estimation method for valley energy and intensity energy are adaptive to the illumination change, the proposed feature extraction method is robust under various conditions.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.219-238
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• 1999

In the present study, laboratory tests including the seepage-induced consolidation test, suction test, and desiccation shrinkage test are performed to investigate characteristics of the desiccation shrinkage in reclaimed hydraulic fills. Soil samples for laboratory tests are obtained from three sites (districts of Haenam, Kogeum and Koheung in Chunnam area). Desiccation shrinkage settlement caused by three dimensional volume change is numerically evaluated using finite difference technique based on the governing equation proposed by Abu-Hejleh & Znidarcic. Also characteristics of the desiccation shrinkage analyzed from the test results are used as input data for numerical evaluations. Further predicted total settlements including the self-weight consolidation settlement are compared with values measured at the site of Haenam district. Finally, effects of parameters related to the desiccation shrinkage on settlements are examined.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.215-228
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• 2002

In a companion paper. (Oh, 2002), the constitutive model, called GUX model, was implemented as a user subroutine in ABAQUS code, where the GUX model could describe the behavior of overall strain range. An accuracy analysis verified that the implicit stress integration maintained the accuracy of solutions successfully. Since the GUX model is an anistropic hardening elasto-plastic constitutive model based on total stress concept, geotechnical problems under fully drained or undrained condition can be analyzed after acquisition of stress-strain relationships from drained or undrained triaxial tests. This study includes the analyses of the stability of embankments on soft clays and weathered soils and the example of axially loaded soil-pile system. In the large deformation analyses, geometric nonlinearity was considered and the result of analyses with GUX model was compared with that of Mises model for the overall strain range behavior.