• KIEE International Transactions on Power Engineering
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• 제3A권3호
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• pp.139-147
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• 2003

The paper presents a novel approach of constructing the state matrix of the multi-machine power system for SSR (subsynchronous resonance) analysis using the linearized equations of individual devices including electrical transmission network dynamics. The machine models in the local d-q reference frame are integrated with the network models in the common R-I reference frame by simply transforming their output equations into the R-I frame where the transformed output is used as the input to the network dynamics or vice versa. The salient feature of the formulation is that it allows for modular construction of various component models without rearranging the overall state space formulation. This universal SSR small signal stability program provides a flexible tool for systematic analyses of SSR small-signal stability impacts of both conventional devices such as generation systems and novel devices such as power electronic apparatus and their controllers. The paper also presents its application results to IEEE benchmark models.

• Asian Journal of Innovation and Policy
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• 제3권1호
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• pp.25-49
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• 2014

We wanted to show the different group dynamics of factors for success and failure cases for technology commercialization in small technology-based firms. Existing studies are based on product level, project level, division level or firm level. We deal with technology level, and at small-technology-based firms. This is a longitudinal case study based on 8 cases from Korea. Our study on technology level is a first trial in success and failure studies unlike all existing studies. As a first step, we introduced new categories and factors such as technology attributes and CEO reflecting data, and especially a new concept of launch readiness level. Finally, we adopted correspondence analysis to show the group dynamics. The results are as follows; Technology factors are the most important factors. Second, resource-based factors are more critical in failure cases than success cases and technology factors are more critical to success.

• 생태와환경
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• 제56권2호
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• pp.172-186
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• 2023

불안정한 천이양상을 보이는 소형 호소는 대형 호소에 비해 동물플랑크톤 군집 동태 연구가 미진한 상황이다. 최근 지역 생물다양성 보전의 측면에서 소형 호소의 존재 가치가 부각되면서 생물 군집 동태 대한 이해의 필요성이 강조되고 있다. 본 연구는 세 소형 호소의 출현 동물플랑크톤을 월별로 채집하여 계절별 군집 동태를 분석하였다. 소형 호소의 복잡한 동물플랑크톤 군집 동태를 파악하기 위해 종 출현 패턴을 기반, 4개의 그룹(LALF Group, Low Abundance Low Frequency; LAHF Group, Low Abundance High Frequency; HALF Group, High Abundance Low Frequency; HAHF Group, High Abundance High Frequency)으로 그룹화하였다. 그룹 간 계절적 패턴을 비교하였으며, 각 그룹의 시간적 베타 다양성 기여도를 기반으로 한 다양성을 산출했다. 분석 결과 같은 출현량 경향을 보이지만 상반된 출현 빈도를 보이는 그룹 간의 관계가 있는 것으로 나타났으며, Nauplius가 세 호소공통으로 높은 출현량과 빈도를 보이는 종으로 나타났다. 적은 개체수를 보이면서 출현 빈도 역시 드물게 나오는 종들이 포함된 그룹인 LALF 그룹에 속한 종이 월별 천이와 다양도에 핵심인 것으로 분석되었으며 해당 그룹에는 Anuraeopsis fissa, Hexarthra mira 및 Lecane luna가 포함되었다. 한편 연중 특정 시기에만 출현하여 수체를 우점하는 종들이 포함된 그룹인 HALF 그룹이 호소 공통적으로 시간적 다양성을 저해하는 것으로 분석되었다. 본 연구의 결과를 통해 종 특이적인 출현 패턴이 연내 군집의 생물다양성에 기여하는 종을 분석하는 데 있어서 핵심적으로 작용할 수 있음을 제안한다.

• 한국시스템다이내믹스연구
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• 제3권2호
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• pp.69-91
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• 2002

This paper presents an analysis of the impact of the causal looping method to the Korean middle managers' decision-making processes. The sample included the observations of decisions made by 70 groups with 5 to 7 members each. The results showed that the causal looping method was a strong device to help Korean managers followed value-focused decision processes, as opposite to alternative-focuses ones. The lessons from this study suggest a direction for the development of the education method to improve group decision-making processes.

• Wind and Structures
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• 제1권4호
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• pp.303-315
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• 1998

Full-scale measurements have been made to determine the increase in wind speed over two exposed embankments, one of $23^{\circ}$ slope and 4.7 m in height, the other of $24^{\circ}$ slope and 7.3 m in height. Measurements were made at heights of 5, 10 and 15 m above the upper edge of each embankment and at the same heights approximately 100 m upwind in the lower-level approach fetch. Despite the modest sizes of the embankments, the maximum recorded increase in mean wind speed was 28% and the minimum was 13%; these increase relate to increases in wind loads on structures erected at the top of the embankments of 64% and 28% respectively. The associated increases in gust speeds are estimated at 33% and 18%, which imply increases in gust loading of 77% and 39% respectively. These experimental results are compared with predictions obtained from a computational fluid dynamics (CFD) analysis, using three high Reynolds number eddy-viscosity models and estimates from the UK wind loading code, BS 6399: Part 2. The CFD results are generally in agreement with the experimental data, although near-ground effects on the embankment crest are poorly reproduced.

• 전기의세계
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• 제29권4호
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• pp.256-259
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• 1980

A singular pertubation theory is applied to obtain an approximate solution for suboptimal control of nuclear reactors with spatially distributed parameters. The inverse of the neutron velocity is regarded as a small perturbing parameter, and the model, adopted for simplicity, is a cylindrically symmetrical reactor whose dynamics are described by the one group diffusion equation with one delayed neutron group. The Helmholtz mode expansion is used for the application of the optimal theory for lumped parameter systems to the spatially distributed parameter systems. An asymptotic expansion of the feedback gain matrix is obtained with construction of the boundary layer correction up to the first order.

• 동서간호학연구지
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• 제14권2호
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• pp.60-66
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• 2008

Background: Communication training in nursing college students is an integral part of the development of their competency in dealing with patients. However, the traditional lecture style of training delivery may not be desirably effective. Purpose: This study investigated the effects of a communication training program utilizing a small group dynamic on the communication competency and human relationships in nursing college students. Methods: One hundred twenty six freshmen in a university in Seoul participated in this study. The instruments of communication competency (Primary Communication Inventory) and human relationships (Relationship Change Scale) were used at the beginning and conclusion of the training period. Eighty-three students from two nursing classes were assigned to the experimental groups and 43 students from other classes were assigned to the control groups. Each of the 11 small groups was composed of 7 or 8 students. The weekly program that ran during the 2007 fall semester from October 1st to December 11th consisted of effective communication strategies including therapeutic communication skills, Johari's window, empathy, active listening, and transactional analysis. Results: The experimental group of students reported significantly greater improvement in communication competencies, specific nonverbal competencies, and human relationships compared with the control group. Specifically, the experimental students demonstrated greater improvement in nonverbal communication competencies and satisfaction, communication, and awareness of human relationships. Conclusions: Small group based communication training can be an effective alternative method of communication education for college nursing students.

• Interaction and multiscale mechanics
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• 제1권4호
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• pp.437-448
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• 2008

This paper examined the stability of high-dense dislocation substructures (HDDSs) associated with martensite laths in High Cr steels supposed to be used for FBR, based on a series of dislocation dynamics (DD) simulations. The DD simulations considered interactions of dislocations with impurity atoms and precipitates which substantially stabilize the structure. For simulating the dissociation processes, a point defect model is developed and implemented into a discrete DD code. Wall structure composed of high dense dislocations with and without small precipitates were artificially constructed in a simulation cell, and the stability/instability conditions of the walls were systematically investigated in the light of experimentally observed coarsening behavior of the precipitates, i.e., stress dependency of the coarsening rate and the effect of external stress. The effect of stress-dependent coarsening of the precipitates together with application of external stress on the subsequent behavior of initially stabilized dislocation structures was examined.

• 영어어문교육
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• 제10권1호
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• pp.77-106
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• 2004

This study aims to investigate how the four college students interact with one another to discuss and construct meaning in a small reading group. Additionally, this study attempts to examine how the participants played their roles in the group. Data sources consisted of transcripts of the students' interactions, questionnaires and informal interviews, and the researchers' observation notes. The data revealed that the participants contributed fairly steadily to the interactions by checking with own grammatical knowledge, providing lexical information, understanding the micro level context, and presenting the macro level context. Several pedagogical implications are presented for the practical classroom. Findings of the study suggest effective ways to implement group activities in reading classes and a teacher's role for optimum group learning.

• Bulletin of the Korean Chemical Society
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• 제16권9호
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• pp.850-858
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• 1995

Golden-rule like formulas have been used without theoretical basis to calculate the resonance lifetimes and final state distributions in the predissociation of van der Waals molecules. Here we present their theoretical basis by extending Fano's configuration interaction theory. Such extensions were independently done by Farnonux [Phys. Rev. 1985, 25, 287] but his work, unfortunately, was not well known outside some small group of people in the field of Auger spectroscopy. Since my extension is easier to understand than his, it is presented here. Theoretical basis of Golden rule like formulas used in the predissociation of van der Waals molecules was obtained by using such extensions. Factors responsible for several aspects of predissociation dynamics, such as variations of dynamics as functions of resonance lifetimes, or variations in shapes of final quantum state distributions of photofragments around resonances, were identified. Parameters, or dynamical information that could be obtained from the measurement of partial cross section spectra were accordingly determined. The theory was applied to the vibrational predissociation of triatomic van der Waals molecules and its result was compared with those calculated by close-coupling method. An example where Golden-rule like expression fails and branching ratios vary greatly around a resonance was considered.