• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.2
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• pp.43-46
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• 1975

In a chopper amplifier the input signal of the AC amplifier is a train of square-waves. In the rase of square-wave the operatiom of AC amplifier is much different from that of ordinary sinusoidal wave. In this paper for the purpose of contributing to the design of chopper amplifier destortions of waveforms in the amplifier were investigated. When the time constant of each stage is equal the waveform in each stave apppears as square wave whose top is exponentially decaying. And when each stave has different time constant the waveform in n-th stage is composed of n-square waves whose tops are exponentially decaying.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.2
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• pp.114-125
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• 2009

Effect of a finite square substrate plane on the radiation characteristics of a microstrip patch antenna is investigated. Effect of a finite square substrate plane on the resonance frequency and bandwidth is very small, while that on the radiation pattern is very large. The gain of front radiation and the direction of the maximum gain vary almost periodically with the length of a square substrate plane. The length of a square substrate plane for the maximum gam and the minimum gain of front radiation decrease as the electrical thickness of a substrate increases. The variation of the gain of front radiation with the length of a square substrate plane increases as the electrical thickness of a substrate increases. The variation of the radiation pattern with the length of a square substrate plane is almost determined by the electrical thickness of a substrate.

• Proceedings of the Korean Society for Environmental Edudation Conference
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• 2003.07a
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• pp.50-56
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• 2003

＃1 The Education from our Environment, The urgent subject for survival and prosperity in the future. - Around Yamaguchi in japan. - ＃2 Days of tour : January, 15, 2003 - January, 28, 2003 ＊ Comprehensive classes involved in ecosystems; Ryojo Elementary school, Guina Elementary school, Dabusei Junior High School, Ube Technical High School, Yashiro Elementary School, Toyota Nishi Junior High School, Seii Elementary School, Yamaguchi Prefectural School for the Mentally Impaired, Yamaguchi Institute for Educational Research and In-service Training, Kirara Beach Nature Watching Park ＃3 Characteristics of Yamaguchi Prefectural Environmental Education - Constant effort by concerned authorities and dedicated teachers - Cooperation of schools with community - Application of the comprehensive classes - Student-centered education through experiences - Acquirement of basic knowledge on environment in their daily lives - The harmony with the ability to survive' ＃4 Characteristics of the environmental education in each school $\square$ Ryojo Elementary School \longrightarrow Breeding the fireflies' larvae and releasing them into nature $\square$ Kuina Elementary School \longrightarrow Keeping the rivers clean $\square$ Yashiro Elementary School \longrightarrow Learning through exploring ‘Akiyoshido Cave’ $\square$ Seii Elementary School \longrightarrow Tree-planting campaign continued for 30 years $\square$ Tabuse Junior High School \longrightarrow Making their village good to live in $\square$ Toyota-Nishi Junior High School \longrightarrow Learning through working on the farm and in the forests $\square$ Ube Technical High School \longrightarrow Purifying the pond by the ‘biotope’ ＃5 Focus on Yashiro Elementary School \longrightarrow Children Guide Activity (25 hours annually) * To love their native place and tourists' attraction, Akiyoshidal * To introduce a variety of local events; - To make a fire in the mountains - To explore the cave - To hold a festival for tourists - To have a family-jointed bike riding ＃6 $\square$ conclusion - Gradual extension of environmental education * individuals \longrightarrow school \longrightarrow community - Finding the environmental problems around themselves and relating them with features of their community < Tips for the environmental education in the future > - Need for encouragement of more lively discussion in class - Expansive application of comprehensive classes to various areas

• Steel and Composite Structures
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• v.21 no.6
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• pp.1227-1250
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• 2016

Most of the research work has been conducted on K-joints under static loading. Very limited information is available in consideration of fatigue strength of K-joints with concrete-filled chord. This paper aims to describe experimental and numerical investigations on stress concentration factors (SCFs) of concrete-filled circular chord and square braces K-joints under balanced axial loading. Experiment was conducted to study the hot spot stress distribution along the intersection of chord and braces in the two specimens with compacting concrete filled in the chord. The test results of stress distribution curves of two specimens were reported. SCFs of concrete-filled circular chord and square braces K-joints were lower than those of corresponding hollow circular chord and square brace K-joints. The corresponding finite element analysis was also conducted to simulate stress distribution along the brace and chord intersection region of joints. It was achieved that experimental and finite element analysis results had good agreement. Therefore, an extensive parametric study was carried out by using the calibrated finite element model to evaluate the effects of main geometric parameters and concrete strength on the behavior of concrete-filled circular chord and square braces K-joints under balanced axial loading. The SCFs at the hot spot locations obtained from ABAQUS were compared with those calculated by using design formula given in the CIDECT for hollow SHS-SHS K-joints. CIDECT Design Guide was generally quite conservative for predicting SCFs of braces and was dangerous for predicting SCFs of chord in concrete-filled circular chord and square braces K-joints. Finally SCF formulae were proposed for circular chord and square braces K-joints with concrete-filled in the chord under balanced axial loading. It is shown that the SCFs calculated from the proposed design equation are generally in agreement with the values derived from finite element analysis, which were proved to be reliable and accurate.

• Journal of Digital Convergence
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• v.19 no.12
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• pp.339-345
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• 2021

In this paper, estimation angle performance analysis of amplitude-comparison monopulse radar under additive noise effect is dealt with. When uncorrelated white noises are added to the squinted beams, the angle estimation performance is analyzed through the mean square error(MSE). The numerical integration-based mean square error result completely overlaps the Monte Carlo-based mean square error result, which corresponds to 99.8% of the Monte Carlo-based mean square error result. In addition, the mean square error analysis method based on numerical integration has a much faster operation time than the mean square error method based on Monte Carlo. the angle estimation performance of the amplitude comparison monopulse radar can be efficiently analyzed in various noise environments through the proposed numerical integration-based mean square error method.

• Journal of the Korean Wood Science and Technology
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• v.31 no.1
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• pp.27-31
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• 2003

This paper presents the results of air-drying processes and mositure content (MC) distribution of red pine (P. densiflora) and Japanese larch (L. leptolepis) square timber with 14 cm and 16.5 cm of face size, respectively. The air-drying rates of square timber were comparatively high during the first 8 weeks, after that gradually decreased. The time to air dry square timber from initial MC to specified MC of 18 percent required about 26 weeks for 14.0 cm and 32 weeks for 16.5 cm square of red pine, and 32 weeks for 14.0 cm and 48 weeks for 16.5 cm square of Japanese larch. The longitudinal- and transverse MC distribution of these air-dried squares showed slight moisture gradient. The effect of face size on moisture gradient of Japanese larch square was more pronounced comparing with red pine one.

• Communications of the Korean Mathematical Society
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• v.29 no.3
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• pp.489-496
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• 2014

We drive a closed-form expression for the price of a European quanto call option in the double square root stochastic volatility model.

• Proceedings of the Korea Society of Costume Conference
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• 2004.05a
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• pp.3-12
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• 2004

$\square$ 디지털폐인 탐구 -폐인, 언어, 리플문화, 사진합성, 그외 작품활동 등 $\square$ 어떻게 읽을 것인가 -가상공간은 포스트 모더니즘의 현대 소비문화가 식민화된 형태 - 폐인사이트 요소분석과 심층인터뷰를 통한 포스트모더니티 분석 $\square$ 소비문화적 함의 - 능동적 소비문화 - 대항적 소비문화 - 키치적 소비문화 (중략)

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.108-112
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• 1986

Several algorithms for bivariate time series modeling are reviewed : linear least square, nonlinear least squares, generalized least square, and multi-stage least square methods. Estimation results of simulated data by the above methods are discussed.

• Proceedings of the Korean DIstribution Association Conference
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• 2000.05a
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• pp.3-19
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• 2000

롯데 인터넷백화점 현황 $\square$ NON - STORE RETAILER : 무점포소매업(통판) $\square$ REAL - RETAILER : 점포소매업(물류기능 + HELP DESK + 카드결제가능) $\square$ E - RETAILER : 편리성(INTERNET / 24H) $\textbullet$ FULFULLMENT:수주에서 배달,고객 고충처리까지 $\textbullet$ 물류기능 + HELP DESK + 카드결제가능 $\textbullet$ REAL- RETAILER + E - RETAILER (중략)