• Title/Summary/Keyword: RESPONSE 2000

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Study on the Seismic response Spectra of a Structure Built on the Deep Soil Layers Classified in UBC-97 (UBC-97에 분류된 깊은 지반위에 세워진 구조물의 지진응답 스펙트럽에 관한 연구)

  • 김용석
    • Journal of the Earthquake Engineering Society of Korea
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    • v.4 no.1
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    • pp.63-76
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    • 2000
  • 구조물-지반 상호작용에서 알려진 것처럼 구조물 지진응답은 구조물하부 지반조거에 따라 영향을 받는데 UBC-97을 포함한 여러내진설계규준에서 지반사태 영향을 반영하고 있다 이 연구에서는 기초크기 기초밑 지반깊이, 입력지진 작용점 및 기초 근입깊이 등의 영향을 살펴보고 깊은 지반 위에 세워진 구조물의 평균응답스펙트럼을 UBC-97 탄성응답스펙트럼과 비교하기 위해 구조물-지반 상호작용을 고려한 지진해석을 가상 3차원 유한요소법과 부구조물법을 이용하여 1952년 Taft와 1940년 El Centro 지진기록을 주파수영역에서 수행하였다 연구결과에 의하면 기초크기는 구조물 응답에 별 영향이 없고 기초저면 지반깊이는 구조물체계의 고유주기와 최대가속도를 변경시켰다 또 입력지진의 합리적 작용점은 기초저면이라는 것이 확인되었으며 깊은 지반위에 놓인 기초의 근입은 저주기영역에서 구조물 응답을 상당히 줄어들게 하였다 한편 30m 깊은 지반위에 세워진 구조물의 평균가속도와 UBC-97 가속도를 비교한 결과 UBC-97 탄성응답스펙트럼에 의한 구조물 내진설계가 안전하지 못할 수도 있으므로 UBC-97 지진계수의 할증이 필요하다.

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Bayesian VAR Analysis of Dynamic Relationships among Shipping Industry, Foreign Exchange Rate and Industrial Production (Bayesian VAR를 이용한 해운경기, 환율 그리고 산업생산 간의 동태적 상관분석)

  • Kim, Hyunsok;Chang, Myunghee
    • Journal of Korea Port Economic Association
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    • v.30 no.2
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    • pp.77-92
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    • 2014
  • The focus of this study is to analyse dynamic relationship among BDI(Baltic Dry-bulk Index, hereafter BDI), forex market and industrial production using monthly data from 2003-2013. Specifically, we have focused on the investigations how monetary and real variable affect shipping industry during recession period. To compare performance between general VAR and Bayesian VAR we first examine DAG(Directed Acyclic Graph) to clarify causality among the variables and then employ MSFE(mean squared forecast error). The overall estimated results from impulse-response analysis imply that BDI has been strongly affected by other shock, such as forex market and industrial production in Bayesian VAR. In particular, Bayesian VAR show better performance than general VAR in forecasting.

Shape and Thickness Optimizations of Prismatic Shells Using a Simple Sweep Geometric Model (스위프 기하학적 모델을 사용한 프리즘 쉘의 최적화)

  • 이상진
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.13 no.2
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    • pp.221-230
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    • 2000
  • Sweep geometric models are based on the notion of moving a curve, surface or solid along some path. Sweeping allows definition of prismatic shell surfaces in a simple way, This paper describes an application of sweep geometric models for the optimization of prismatic shells. This geometric model is integrated with finite element formulations. A nine-node degenerated shell element is adopted to calculate the response of prismatic shells. Several examples we presented to demonstrate the process of optimization. From numerical examples, it is observed that sweep geometric models provide an efficient and reliable way of obtaining optimal solutions for a large class of prismatic shell structures.

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Stochastic Response of a System with Autoparametric Coupling (자기매계변수 연성을 갖는 응답의 통계적 특성)

  • 조덕상;김영종
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.13 no.4
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    • pp.387-394
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    • 2000
  • The nonlinear modal interaction of an autoparametric system under a broadband random excitation is investigated. The specific system examined is an autoparametric vibration absorber with internal resonance, which is typical of many common structural configurations. By means of Gaussian closure scheme the dynamic moment equations explaining the random responses of the system are reduced to a system of autonomous ordinary differential equations of the first and second moments. In view of equilibrium solutions of this system and their stability we examine the system responses. We could not find the destabilizing effect of damping, which was reported in References (18) and (20). The saturation phenomenon, which is well known in deterministic nonlinear system, did not take place lot this system subject to broadband random excitation.

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Electromagnetic Strip Stabilization Control in a Continuous Galvanizing Line using Mixture of Gaussian Model Tuned Fractional PID Controller (비정수 차수를 갖는 비례적분미분제어법과 가우시안 혼합모델을 이용한 연속아연도금라인에서의 전자기 제진제어 기술)

  • Koo, Bae-Young;Won, Sang-Chul
    • Journal of Institute of Control, Robotics and Systems
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    • v.21 no.8
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    • pp.718-722
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    • 2015
  • This paper proposes a fractional-order PID (Proportional-Integral-Derivative) control used electromagnetic strip stabilization controller in a continuous galvanizing line. Compared to a conventional PID controller, a fractional-order PID controller has integration-fractional-order and derivation-fractional-order as additional control parameters. Thanks to increased control parameters, more precise controller adjustment is available. In addition, accurate transfer function of a real system generally has a fractional-order form. Therefore, it is more adequate to use a fractional-order PID controller than a conventional PID controller for a real world system. Finite element models of a $1200{\times}2000{\times}0.8mm$ strip, which were extracted using a commercial software ANSYS were used as simulation plants, and Gaussian mixture models were used to find optimized control parameters that can reduce the strip vibrations to the lowest amplitude. Simulation results show that a fractional-order PID controller significantly reduces strip vibration and transient response time than a conventional PID controller.

A Study on Weight Reducing Methods of Women Living in Inchon (인천지역 여성의 체중감량법에 대한 조사 연구)

  • 우경자;천종희;최은옥
    • Journal of the East Asian Society of Dietary Life
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    • v.10 no.6
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    • pp.530-540
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    • 2000
  • Weight reducing methods were surveyed by questionnares in March through May, 1998 with 641 women living in Inchon to provide the information for the education of proper weight control. Methods that they have used for weight-reduction were exercise (33.1%), diet therapy(29.6%), sauna(7.3%), ingestion of special food(4.8%), administration of drugs(4.0%) and herb-medicines. The respondents considered exercise(38.4%) and diet therapy(31.5%) as the most effective methods in reducing weight and the response was different with ages at p<0.01. They have practiced the diet therapy by reducing the amount of food(27.7%), skipping one or two meals a day (20.8%), avoiding high calorie snacks(8.8%) and regulating food items in a meal(3.8%). Exercises which they have done were walking(48.0%), aerobics(2.3%), swimming(23%) and using the health instruments(6.7%). Their choices in kinds of exercises were significantly dependent upon ages, marriage and their occupation(P<0.01). Acupuncture(38.0%) was the most frequently used oriental medicine therapy and original drugs(32.2% ) and moxibustion(22.0%) were also used. The women have taken drugs was 9.5%. Among them cream-typed cosmetics(41%), weight reducing drugs(30%), diuretics(18% ), and smoking(7%) were used. Fifty respondents out of 641 had expericences to have special food therapy such as grape, apples and vinegar(42%) and enzymes(18%) for some period of time.

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Effects of auricular acupuncture on cholecytokinin in cerebral cortex of sprague dawley rats (이침(耳鍼)이 절식(絶食)시킨 흰쥐의 대뇌피질(大腦皮質)에서 CCK 활성변화(活性變化)에 미치는 영향(影響))

  • Kim, Ee-Hwa;Kim, Youn-Jung;Lim, Baek-Vin;Jang, Mi-Hyun;Chung, Joo-Ho;Kim, Chang-Ju
    • Journal of Acupuncture Research
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    • v.17 no.3
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    • pp.168-175
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    • 2000
  • Stimulation of the auricle is known to be effective in reducing obesity. The aim of the present study is to investigate whether stimulating a specific auricular acupuncture point is effective on suppression of appetite. Cholesystokinin (CCK) is known to induce a powerful feeding response after central administration and particularly abundant in the cerebral cortex. In food-deprived rats exhibiting a strong drive for feeding, decreased CCK release was markedly detected in the cerebral cortex of the brain. Needling the fasted rats on the specific auricular region increased the CCK level of the cerebral cortex. In conclusion, stimulating the specific auricular points increases CCK-expression in the cerebral cortex of the fasted rats and may be useful for controlling obesity.

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Trends of the researches related to ethical topic in Korean nursing students (국내 간호학생 대상 윤리관련 연구 동향)

  • Jin, Eunju;Kang, Hyunju
    • The Journal of Korean Academic Society of Nursing Education
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    • v.26 no.4
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    • pp.402-411
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    • 2020
  • Purpose: The purpose of this study is to explore the trends of research related to ethical topics in Korean nursing students. Methods: A total of 131 articles that were published from 2000 to 2020 were analyzed and summarized according to publishing type, research design, subject, data analysis method, main research topic, research variables and instrument. Results: Most studies were journal articles (93.9%) and their most frequent research design was survey (75.7%). The research subjects covered all grades (35.1%) or they were divided between clinical nursing practicum (29.8%) or not (21.4%). The main research topics were biomedical ethics, ethical values, moral judgment and ethics education. Recently, ethical decision making and practical ability in nursing practice were reported. The instruments for measuring variables were limited and the same tools were used several times. Conclusion: Based on the findings of this study, it is suggested that the selection of various research topics and the application of research methods related to ethics for nursing students will continue in response to rapidly changing social phenomena in the future. In particular, it is necessary that research related to ethical and practical ability as well as ethical attitudes and perceptions of nursing students be actively carried out.

Cyberspace and survey research: The methodological implications and issues of online survey research (사이버공간과 사회조사:온라인 사회조사의 쟁점과 과제)

  • 조동기
    • Survey Research
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    • v.1 no.1
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    • pp.73-108
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    • 2000
  • This study investigates methodological implications of cyberspace and information technology for online survey research Online survey method provides useful methodological tools for collecting empirical data for the study of cyberspace, In terms of sampling frame , selection method, and questionnaire from four major types of the online survey research can be found: member survey visitor survey e-mail survey and the electronic survey. Online survey research with sample design(population specification error. sampling frame error, selection error) measurement (measurement instrument bias system-related processing error, nonrespone, and response bias) and research ethics (privacy and netiquette) pose important methodological issues for the survey. The realization of the technological possibilities of online survey will be possible only through a right consideration of these issues.

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Imputation Methods for Nonresponse and Their Effect (무응답 대체 방법과 대체 효과)

  • Kim, Kyu-Seong
    • Survey Research
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    • v.1 no.2
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    • pp.1-14
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    • 2000
  • We consider statistical methods for nonresponse problem in social and economic sample surveys. To create a complete data set, which does not include item nonresponse data, imputation methods are generally used. In this paper, we introduce some imputation methods and compare them with one another. Also, we consider some problems, which occur when an imputed data set is treated as a response data set. Due to the imputed values, the true variance of the estimator after imputation is increased by the imputation variance. However, since usual naive variance estimator constructed from the imputed data set does not estimate the imputation variance, the true variance of the estimator after imputation tends to be underestimated. Theoretical reason is investigated and serious results are explained through a simulation study. Finally, some adjusted variance estimation methods to compensate for underestimation are presented and discussed.

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