• 한국통신학회논문지
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• 제21권3호
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• pp.771-783
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• 1996

8단자 가변임피던스 전자파 발생장치(8P-VWIG:8Ports-Variable Wave Impedance Generator)에 대한 설계 기술에 대해 나타내고, 내부에서 유기뇌는 전자기장 및 특성임피던스에 대한 수치해석, 일정한 특성임피던스를 갖는 구조에 대해 간단하게 추적할 수 있는 수치알고리즘에 대해 나타내었다. 또한 특정 구조에 대한 균일도 평가결과와 내부 전자계 분포, 그리고 그 응용으로서 EMS 측정시스템에 대한 간단한 소개를 나타내었다. 8P-VWIG는 기존 간이 EMI/EMS 시설들에 비해 시험공간의 활용도가 좋고, 수직 수평 분극 조성이 자유로운 장점을 가지고 있다. 제작된 8P-VWIG는 정재파비로 측정된 제 1공진이 152.1MHz에서 발생하고, $50{\Omega}$ 임피던스 정합 시스템으로 동작하도록 한 8채널의 다중전송선로 구조를 갖는다.

• ETRI Journal
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• 제33권3호
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• pp.335-343
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• 2011

The pad pitch of modern radio frequency integrated circuits is in the order of few tens of micrometers. Connecting a large number of high-speed I/Os to the outside world with good signal fidelity at low cost is an extremely challenging task. To cope with this requirement, we need reflection-free transmission lines from an on-chip pad to on-board SMA connectors. Such a transmission line is very hard to design due to the difference in on-chip and on-board feature size and the requirement for extremely large bandwidth. In this paper, we propose the use of narrow tracks close to chip and wide tracks away from the chip. This narrow-to-wide transition in width results in impedance discontinuity. A step change in substrate thickness is utilized to cancel the effect of the width discontinuity, thus achieving a reflection-free microstrip. To verify the concept, several microstrips were designed on multilayer FR4 PCB without any additional manufacturing steps. The TDR measurements reveal that the impedance variation is less than 3 ${\Omega}$ for a 50 ${\Omega}$ microstrip and S11 better than -9 dB for the frequency range 1 GHz to 6 GHz when the width changes from 165 ${\mu}m$ to 940 ${\mu}m$, and substrate thickness changes from 100 ${\mu}m$ to 500 ${\mu}m$.

• 한국과학교육학회지
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• 제12권2호
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• pp.1-18
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• 1992

The curriculum especially in Korea plays a crucial role in developing instructional materials. It serves as a criterion for selecting and organizing content of teaching materials. Therefore, the validity of a curriculum can be justified through testing effectiveness of an instructional material developed in accordance with the curriculum. This paper presents an instructional method and material developed based on the current tendency of educational thoughts that emphasize STS and students - centered teaching strategies in science education. The instructional material was organized around the concept and its subconcept of "nutrition" as presented in the high school biology textbooks now in use in the nation as well as in a few world-wide countries. It was also organized by the use of biological events and phenomena which high school students in rural areas can easily encounter through their everyday lives. The significant findings in this study are : ${\circ}$ The achievement levels in experimental groups were higher than one in controlled groups. ${\circ}$ The students as well as the teachers involved in this study showed positive attitude toward the instructional method developed in the process of this study. ${\circ}$ The greater part of the students among the controlled groups hoped that biology would be taught by this kind of teaching procedure and materials.

• Corrosion Science and Technology
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• 제7권4호
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• pp.212-218
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• 2008

Inorganic ion exchange compounds (IECs) including hydrotalcites and bentonite clays are a well known classes of layered mixed metal hydroxides or silicates that demonstrate ion exchange properties. These compounds have a range of applications from water purification to catalyst supports. The use of synthetic versions of these compounds as environmentally friendly additives to paints for storage and release of inhibitors is a new and emerging application. In this paper, the general concept of storage and release of inhibiting ions from IEC-based particulate pigments added to organic coatings is presented. The unique aspects of the IEC structure and the ion exchange phenomenon that form the basis of the storage and release characteristic are illustrated in two examples comprising an anion exchanging hydrotalcite compound and a cation exchanging bentonite compound. Examples of the levels of corrosion protection imparted by use of these types of pigments in organic coatings applied to aluminum alloy substrates is shown. How corrosion inhibition translates to corrosion protection during accelerated exposure testing by organic coatings containing these compounds is also presented.

• 천문학회지
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• 제41권4호
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• pp.99-107
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• 2008

When a new counting experiment is proposed, it is crucial to predict whether the desired source signal will be detected, or how much observation time is required in order to detect the signal at a certain significance level. The concept of the a priori prediction of the detection limit in a newly proposed experiment should be distinguished from the a posteriori claim or decision whether a source signal was detected in an experiment already performed, and the calculation of statistical significance of a measured source signal. We formulate precise definitions of these concepts based on the statistical theory of hypothesis testing, and derive an approximate formula to estimate quickly the a priori detection limit of expected Poissonian source signals. A more accurate algorithm for calculating the detection limits in a counting experiment is also proposed. The formula and the proposed algorithm may be used for the estimation of required integration or observation time in proposals of new experiments. Applications include the calculation of integration time required for the detection of faint emission lines in a newly proposed spectroscopic observation, and the detection of faint sources in a new imaging observation. We apply the results to the calculation of observation time required to claim the detection of the surface thermal emission from neutron stars with two virtual instruments.

• Earthquakes and Structures
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• 제8권3호
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• pp.591-617
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• 2015

Standards for seismic assessment and retrofitting of buildings provide deformation limit states for structural members and connections. However, in order to perform fully consistent performance-based seismic analyses of soil-structure systems; deformation limit states must also be available for foundations that are vulnerable to nonlinear actions. Because such limit states have never been established in the past, a laboratory testing program was conducted to study the rotational capacity of small-scale foundation models under combined axial load and moment. Fourteen displacement-controlled monotonic and cyclic tests were performed using a cohesionless soil contained in a $2.0{\times}2.0{\times}1.2m$ container box. It was found that the foundation models exhibited a stable hysteretic behavior for imposed rotations exceeding 0.06 rad and that the measured foundation moment capacity complied well with Meyerhof's equivalent width concept. Simplified code-based soil-structure analyses of an 8-story building under an array of strong ground motions were also conducted to preliminary evaluate the implication of finite rotational capacity of vulnerable foundations. It was found that for the same soil as that of the experimental program foundations would have a deformation capacity that far exceeds the imposed rotational demands under the lateral load resisting members so yielding of the soil may constitute a reliable source of energy dissipation for the system.

• Tribology and Lubricants
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• 제32권6호
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• pp.189-194
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• 2016

Wear debris in lubricating oil can be indicative of potential damage to mechanical parts in rotating and reciprocating machinery. Therefore, on-line or in-line monitoring of lubricating components in machinery is of great importance. This work presents a device based on inductive measurement of lubricating oil to detect magnetic wear particles in a tested volume. The circuit in the device consists of Maxwell Bridge and LVDT to measure inductance differences between pure and contaminated oil. The device detects the passage of ferrous particles by monitoring inductance change in a coil. The sensing principle is initially demonstrated at the microscale using a solenoid. The device is then tested using iron particles ranging from $50{\mu}m$ to $100{\mu}m$, which are often found in severely worn mechanical components. The test results show that the device is capable of detecting and distinguishing ferrous particles in lubricating oil. The design concept demonstrated here can be extended to an in-line monitoring device for real-time monitoring of ferrous debris particles. A simulation using the CST code is performed to better understand the inductive response in the presence of magnetic bodies in the oil. The CST simulation further verifies the effectiveness of inductance measurement for monitoring magnetic particles within a tube.

• 대한미생물학회지
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• 제22권2호
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• pp.125-130
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• 1987

The role of enteropathogenic Escherichia coli(EPEC) was evaluated in a group of children with endemic diarrhea admitted to Hanyang University Hospital in Seoul, Korea. EPEC was detected in fecal samples of 23% of 100 cases and 4.5% of 44 concurrent control children. The most commonly isolated EPBC strains were serogroups $O_{18a}O_{18c}:K_{77},\;O_{86a}:K_{61},\;O_{119}:K_{69},\;and\;O_{128}:K_{70}$. On testing for enterotoxin production, 6(26%) strains were isolated from 17% of the 100 diarrheal children and in 4.5% of the 44 well controls(P<0.05). Our study supports the concept that EPEC may be an important cause of endemic diarrheas in Korea.

• 정보처리학회논문지D
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• 제16D권1호
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• pp.65-72
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• 2009

현재 컴포넌트 기반 개발 기법은 재사용성과 생산성 측면에서 효과적인 소프트웨어 개발 방법으로 많은 각광을 받고 있다. 하지만 기존의 UML을 이용한 컴포넌트 기반 개발에서는 컴포넌트의 행위를 배제하고 컴포넌트 인터페이스만 참조하여 컴포넌트를 설계함으로써, 컴포넌트의 구체적인 행위에 대한 파악과 컴포넌트 간 인터페이스 호환성 보장이 불가능하다. 이에 따라 컴포넌트 설계 단계에서 컴포넌트의 행위를 상태기계 다이어그램으로 표현하고, 표현된 상태기계 다이어그램을 통해 컴포넌트의 행위 호환성을 보장할 필요가 있다. 이 연구에서는 상태기계 다이어그램으로 표현된 컴포넌트의 행위를 관찰 일치(observation equivalence)와 호출 일관성(invocation consistency)의 개념을 이용하여 행위 호환성을 검증하는 방법을 제공하고, 동적으로 이를 수행하는 도구를 개발한다.

• 산업융합연구
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• 제2권2호
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• pp.47-68
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• 2004

The term "social marketing" was first introduced in 1971 to describe the use of marketing principles and techniques to advance a social cause, idea, or behavior. Social Marketing is a strategy for changing behavior. It utilizes concepts of market segmentation, consumer research, product concept development and testing, directed communication, facilitation, incentives, and exchange theory to maximize the target adopters' response. Social marketing requires knowledge of each target-adopter group, including its 1. social demographic characteristics, 2. psychological profile and 3. behavioral characteristics. To know the target adopters in these three related ways enables social marketer to make more accurate predictions. In addition to differentiating among and selecting target adopter groups, the social marketer will identify influence-holding groups, or influentials, who can affect a program's success. Great changes and opportunities exist to produce changes in the ways that individuals and groups think and behave and in meeting human needs. The balance of the scales of social change, we hope, will shift away from the use of force and violence to the use of persuasion and voluntary action. I trust that this dissertation will be useful highlighting the strategies and means of peaceful, planned social change designed to elevate the quality of life.