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전하 분리와 축적을 통한 물의 슬로싱 현상 기반 전기에너지 발생 장치
차경환,허덕재,이상민 한국전기전자재료학회 2022 전기전자재료학회논문지 Vol.35 No.1
Liquid-based Triboelectric nanogenerator (L-TENG) is one of the alternatives to solid-based Triboelectric nanogenerator (S-TENG) because of the absence of surface damage which can decrease the durability of the generator. However, the L-TENG also has an obvious drawback of significantly lower output than that of S-TENG. This article produces watersloshing-based electricity generating device (W-ED) with a new design of L-TENG that improves electrical output in portable form. The dual-electrode system, consisting of closed-loop circuit and inner electrode which enables water to contact directly in the bottle, can generate the open-circuit voltage and the short-circuit current of up to 348 V and 5.1 mA, respectively. By investigating the motion of water for each frequency, we propose that W-ED is suitable device for a variety of human motions. We expect that W-ED can be applied in small electrical devices or sensors in daily-use items.
Primary Melanoma of the Spinal Cord의 治驗例
車慶煥,孫晋式,李炳孝 中央醫學社 1971 中央醫學 Vol.20 No.2
A case of primary malignant melanoma was reported in 24 years old male soldier. It was verified with the results of an operative and pathological findings that the lesion involved C3 in the spinal canal. The available references were reviewed and this case in found to be extremely rare.
MINT 필터링에 의한 스테레오 음향 반향 제거기의 성능 향상
차경환 한국음향학회 2002 韓國音響學會誌 Vol.21 No.1
본 논문에서는 스테레오 음향 반향 제거기의 성능을 향상시킬 수 있는 새로운 전처리 방법의 반향 제거기를 제안한다. 제안한 반향 제거기는 MINT (Multiple input/output INverse Theorem) 필터링에 의해 실내 전달함수의 잔향이 저감되어진 입력을 사용함으로써 필터계수의 추정오차를 감소시켜 성능을 향상시킬 수 있었다. 실제의 스테레오 음성과 실제 음장의 전달함수를 사용한 시뮬레이션 결과, 제안한 방법이 NLMS (Normalized Least Mean Square)와 Projection 등의 적응 알고리즘 종류에 관계없이 ERLE가 3∼5 dB 향상됨을 확인하였다. In this paper, a new pre-processing algorithm is proposed to improve the performance of stereo acoustic echo canceller. The proposed algorithm has the improved performance by the estimation error reduction of filter coefficient using input signal which was reduced reverberation of room in the basis MINT (Mu1tip1e-input/output Inverse Theorem) filtering. For real stereo speech signal and real room impulse response the results of simulation, we showed that the proposed method could improved 3∼5 dB ERLE (Echo Return Loss Enhancement) regardless of NLMS (Normalized Least Mean Square) and Projection adaptive algorithm.
제7차 교육과정에 의한 고등학교 영어 교과서 듣기 활동 분석
차경환,홍서경 中央大學校 韓國敎育問題硏究所 2002 韓國敎育問題硏究所論文集 Vol.- No.17
The purpose of this study is to anlayze listening activities in high school English textbooks and to ascertain whether the results are applicable to the 7th national curriculum aims. Based on the analysis criteria presented by Morley(1991), Richards(1983), and Ur(1984), two different analysis cirteria were applied for an in-depth analysis of the listening activities involved in the textbooks. The results of the analysis show that the philosophy of the 7th national curriculum is properly reflected in some parts of the textbooks. On the other hand, some listening activitis in textbooks are emphasized insufficiently and improperly. Through the results of the study, it is presented that the textbook should be designed and improved for the development of students' listening abilities and their communicative competence with the contents of more various and balanced listening activities.
TOEFL의 듣기문항 분석을 통한 한국대학생 듣기 학습효과
차경환,유윤희 한국음성과학회 2000 음성과학 Vol.7 No.2
The aim of this paper was to diagnose Korean college students' listening skills on the TOEFL. The researchers indentified which section, among the TOEFL listening Part A, B, and C, is most easily teachable/ improvable during the period of a semester. First, the result of this research show that Korean students tend to have lower scores in Part A than Part B or Part C. The results indicate that the short informal conversation doesn't give sufficient clues to students, and they don't have enough time to infer the answer. Second, the results revealed that.students showed the lowest progress in Part B after they studied TOEFL listening items and essential idioms for the listening section for 13 weeks. Because students didn't have much experience learning the informal conversation as opposed to the formal one in English, it is harder to achieve an improved grade in Part B, which consists of the informal conversation. But after a semester-long listening course, the average score on TOEFL listening sections increased. Keywords : listening, learning effects, TOEFL analysis
차경환,김의진,이순원 성균관대학교 기초과학연구소 1993 論文集 Vol.44 No.2
Zr(acac)Cl_3(THF) 및 Zr(acac)_2Cl_2(acac=acetylactate, CH_3COCHCOCH_3^1) 화합물이 [Li(THF)_x][PhNN=NNPh], Ⅰ, 리간드와 반응하여 각각 Zr(=NPh)(acac)CI(THF), Ⅱ, 및 Zr(=NPh)(acac)_2, Ⅲ, 착화합물을 생성하였다. 이들을 ^1H-NMR, FTIR 스펙트럼으로 분석하였다. Reactions between Zr(acac)CI_3(THF) and Zr(acac)_2Cl_2(acac=CH_3 COCHCOCH_3^1) with [Li(THF)_x][PhNN=NNPh], Ⅰ, led to Zr(=NPh)(acac) Cl(THF), Ⅱ, and Zr(=NPh)(acac)_2, Ⅲ, respectively. They have been characterized by ^1H-NMR and FTIR spectroscopy.
차경환 東西大學校 2001 동서논문집 Vol.7 No.-
In this paper, we implemented a realtime digital reverberator using feedback type IIR filter and variable index method. This reverberator can reduce the amount of calculation by directly convolution. Also the variable index method can minimize the memory of the reverberant system. So it can represent a various reverberation effect by using recorded room impulse response. The result of reverberator implementation using TMS320C32 DSP Board, we could felt a sense of distance and a space perception in a virtual room.
차경환 東西大學校 2001 동서논문집 Vol.7 No.-
In this paper, we implemented the real-time active noise control of system using SISO method. This algorithm could settle the howling problem, which the MIMO system has in general. The SISO system which one microphone can not only input the signal but also observe the error signal was implemented with TMS320C32 DSP Board. Experimental results demonstrate that the noise level was reduced about 80% when the noise level was measured inside closed box after noise source radiated to the closed box.