• Journal of electromagnetic engineering and science
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• 제17권4호
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• pp.178-180
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• 2017

This study presents a 2-20 GHz monolithic distributed power amplifier (DPA) using a $0.25{\mu}m$ AlGaN/GaN on SiC high electron mobility transistor (HEMT) technology. The gate width of the HEMT was selected after considering the input capacitance of the unit cell that guarantees decade bandwidth. To achieve high output power using small transistors, a 12-stage DPA was designed with a non-uniform drain line impedance to provide optimal output power matching. The maximum operating frequency of the proposed DPA is above 20 GHz, which is higher than those of other DPAs manufactured with the same gate-length process. The measured output power and power-added efficiency of the DPA monolithic microwave integrated circuit (MMIC) are 35.3-38.6 dBm and 11.4%-31%, respectively, for 2-20 GHz.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 1998년도 가을 학술발표논문집 Vol.25 No.2 (2)
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• pp.384-386
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• 1998

The use of hand gesture provides an attractive alternative to cumbersome interface devices for human-computer interaction(HCI). Many methods hand gesture recognition using visual analysis have been proposed such as syntactical analysis, neural network(NN), Hidden Markov Model(HMM) and so on. In our research, a HMMs is proposed for alphabetical hand gesture recognition. In the preprocessing stage, the proposed approach consists of three different procedures for hand localization, hand tracking and gesture spotting. The hand location procedure detects the candidated regions on the basis of skin-color and motion in an image by using a color histogram matching and time-varying edge difference techniques. The hand tracking algorithm finds the centroid of a moving hand region, connect those centroids, and thus, produces a trajectory. The spotting a feature database, the proposed approach use the mesh feature code for codebook of HMM. In our experiments, 1300 alphabetical and 1300 untrained gestures are used for training and testing, respectively. Those experimental results demonstrate that the proposed approach yields a higher and satisfying recognition rate for the images with different sizes, shapes and skew angles.

• 한국통신학회논문지
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• 제17권1호
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• pp.20-28
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• 1992

조음결합은 연결단어 음성인식에서 오인식을 발생시키는 주된 요인이다. 본 연구에서는 표준패턴의 접속 부분에서 선행단어의 영향을 받아 후속단어의 선두 부분하는 것을 고려해 조음결합 모델을 적용하여 후속단어에 변형을 주었다. 조음결합 모델은 임계제동형 선형 2차계를 이용하였으며 1단 DP매칭 인식 알고리즘에 이 모델을 조합하여 효과를 조사했다. 그 결과 화자 5명에 의한 4연 숫자음 35어의 인식 실험에서 조음결합 처리에 의한 인식율이 평균 4.7%개선 되었다.

• Journal of electromagnetic engineering and science
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• 제9권1호
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• pp.7-11
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• 2009

An Ultra-WideBand(UWB) Low-Noise Amplifier(LNA) is proposed and is implemented in a $0.18-{\mu}m$ CMOS technology. The proposed UWB LNA provides excellent wideband characteristics by combining a High-Pass Filter (HPF) with a conventional resistive-loaded LNA topology. In the proposed UWB LNA, the bell-shaped gain curve of the overall amplifier is much less dependent on the frequency response of the HPF embedded in the input stage. In addition, the adoption of fewer on-chip inductors in the input matching network permits a lower noise figure and a smaller chip area. Measurement results show a power gain of + 10 dB and an input return loss of more than - 9 dB over 2.7 to 6.2 GHz, a noise figure of 3.1 dB at 3.6 GHz and 7.8 dB at 6.2 GHz, an input PldB of - 12 dBm, and an IIP3 of - 0.2 dBm, while dissipating only 4.6 mA from a 1.8-V supply.

• 정보관리학회지
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• 제1권1호
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• pp.146-161
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• 1984

오늘날 정보검색(情報檢索)시스팀의 대표적(代表的)인 한 유형(類型)으로서 널리 보급(普及)되어 운영(運營)되고 있는 SDI(Selective Dissemination of Information)시스팀에 관(關)하여 기술(記述)하였다. 이것은 컴퓨터기술(技術)의 정보검색(情報檢索)에의 응용(應用)으로서 이용자(利用者)의 요구(要求) 주제(主題) 부합(符合)되는 문헌(文獻)을 검색(檢索)하기 위하여 색인어(索引語)와 일치(一致)(match)되는 문헌(文獻)을 탐색(探索)하는데 이용(利用)되는 시스팀을 설명(說明)하기 위해 자주 쓰여지는 용어(用語)이다. SDI시스팀을 개발(開發)한 "Luhn"이 최초(最初)로 그 개념(槪念)을 발표(發表)한 이래(以來) 지금까지 개발(開發)되어온 각종(各種)의 SDI시스팀들을 조사(調査) 비교(比較)하고, 이 시스팀들의 발전단계(發展段階), 구성(構成) 및 특성(特性)과 시스팀설계(設計)에 관(關)한 제문제점등(諸問提點等)에 대(對)해서도 분석(分析) 조사(調査)하였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권3호
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• pp.232-238
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• 2008

In this paper, a wideband power efficient 2.2 GHz - 4.9 GHz Medium Power Amplifier (MPA), has been designed and fabricated using $0.8{\mu}m$ SiGe BiCMOS process technology. Passive elements such as parallel-branch spiral inductor, metal-insulator-metal (MIM) capacitor and three types of resistors are all integrated in this process. This MPA is a two stage amplifier with all matching components and bias circuits integrated on-chip. A P1dB of 17.7 dBm has been measured with a power gain of 8.7 dB at 3.4 GHz with a total current consumption of 30 mA from a 3 V supply voltage at $25^{\circ}C$. The measured 3 dB bandwidth is 2.7 GHz and the maximum Power Added Efficiency (PAE) is 41 %, which are very good results for a fully integrated Medium PA. The fabricated circuit occupies a die area of $1.7mm{\times}0.8mm$.

• Journal of Construction Engineering and Project Management
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• 제3권1호
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• pp.35-38
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• 2013

No single project is identical to one another in the construction industry. Furthermore, many construction projects are suffering from tighter budget, shortened schedule and higher client satisfaction level. To overcome these, project managers and engineers are willing to apply various best management practices to their projects. However, it is non-trivial to select the most appropriate practices for their projects. In many cases, it is much more important to find the appropriateness of the management practices than just to use the practices. Although many researchers are focusing on the development of new management practices, there is little research on matching between the circumstances of projects and the developed management practices. The objective of this study is to provide a structured process to suggest the best management practices for individual construction projects by developing a computerized system where an individual project is matched with the most optimal management practices to increase the value of the project. At this stage of writing, the authors have developed a computerized system to effectively find out the best suitable management practices for individual projects. By maximizing the usages of this system, it would facilitate the application of the best management practices in the industry.

• ETRI Journal
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• 제38권5호
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• pp.972-980
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• 2016

An ultra-wideband microwave monolithic integrated circuit high-power amplifier with excellent input and output return losses for phased array jammer applications was designed and fabricated using commercial $0.25-{\mu}m$ AlGaN/GaN technology. To improve the wideband performance, resistive matching and a shunt feedback circuit are employed. The input and output return losses were improved through a balanced design using Lange-couplers. This three-stage amplifier can achieve an average saturated output power of 15 W, and power added efficiency of 10% to 28%, in a continuous wave operation over a frequency range of 6 GHz to 18 GHz. The input and output return losses were demonstrated to be lower than -15 dB over a wide frequency range.

• 대한조선학회논문집
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• 제35권4호
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• pp.109-117
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• 1998

선박의 개념설계 단계는 이용 가능한 정보가 매우 제한되어 있기 때문에 새로운 설계를 위하여 대부분의 경우 기존 선박의 설계 사례를 이용하게 된다. 본 논문에서는 이러한 과정을 시스템화하여 사례기반 선박 개념설계 시스템을 개발하였다. 개발된 시스템은 사례 인덱싱을 통한 설계후보의 생성뿐만 아니라 nearest neighbor algorithm을 이용하여 사례베이스에서 추출된 설계 사례들의 우선 순위를 결정하여 주고 이를 바탕으로 변용(adaptation) 과정을 거쳐 설계선에 대한 해를 제시해 준다. 이러한 사례기반 추론 기법을 선박 개념설계 단계에 적용하여 그 유용성을 검증하였다.

• 대한산업공학회지
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• 제24권4호
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• pp.649-660
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• 1998

Steel making in Mini Mill consists of three major processing stages: molten steel making in an electric arc fuenace, slab casting in a continuous caster, and hot rolling in a finishing mill. Each processing stage has its own lot grouping criterion. However, these criteria in three stages are conflicting with each other. Therefore, delveloping on efficient lot grouping algorithm to enhance the overall productivity of the Mini Mill is an extremely difficult task. The algorithm proposed in this paper is divided into three steps hierarchically: change grouping, cast grouping, and roll grouping. An efficient charge grouping heuristic is developed by exploiting the characteristics of the orders, the processing constraints and the requirements for the downstream stages. In order to maximaize the productivity of the continuous casters, each cast must contain as many charges as possible. Based on the constraint satisfaction problem technique, an efficient cast grouping heuristic is developed. Each roll consists of two casts satisfying the constraints for rolling. The roll grouping problem is formulated as a weighted non-bipartite matching problem, and an optimal roll grouping algorithm is developed. The proposed algorithm is programmed with C language and tested on a SUN Workstation with real data obtained from the H steel works. Through the computational experiment, the algorithm is verified to yield quite satisfactory solutions within a few minutes.