• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.471-477
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• 2003

The floating ring seal is often used in the turbopump (TP) unit of liquid rocket engine (LRE) owing to its inherent ability of minimizing the leakage flow and superior dynamic characteristics as well. This paper describes the test results concerned with the lock-up and dynamic characteristics of the floating ring seals in the turbopump. The characteristics of the floating ring seals were extracted from the frequency response function (FRF) by instrumental variable method. The experiment was tested at 7.0MPa and 0-24,800 rpm. And the test results were introduced about the dynamic characteristics of floating ring seal related with the eccentricity and attitude angle.

• 의학교육논단
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• 제12권1호
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• pp.3-8
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• 2010

This study is designed to evaluate the effectiveness of teaching or studying programs, and thus to overcome the selectionbias in studies. Selection-bias derived from unobservable characteristics in the course of participants selection of the teaching or studying programs, in the case of cross-section data instrumental variable(IV) method and two stage least square estimation were suggested as an analysis tool. Panel data were analyzed by using both fixed effect in which individual effects are captured by intercept terms and random effect estimation where an unobserved effect can be characterized as being randomly drawn from a given distribution.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.186-194
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• 2004

Experiments were conducted to determine the structural static and dynamic characteristics of air foil bearings. The housing of the bearing on the journal was driven by an impact hammer which was used to simulate dynamic forces acting on the bump loll with various leading condition. Two different bump foils (Cu-coated bump and viscoelastic bump) were tested and the static and dynamic coefficients of two bump foils compared, based on the experimental measurements for a wide range of operating conditions. The static and dynamic characteristics of air foil bearings were extracted 0rpm the frequency response function by least square method and IV(Instrumental Variable) method. The experiment was tested at 0rpm and $10,000\~16,000rpm$, and loaded on $50\~150N$. From the test results, the possibility of the application of high load and high speed condition is suggested.

• 한국의류학회지
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• 제26권5호
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• pp.663-674
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• 2002

The objectives of this study were 1) to ascertain whether there was a difference in product performance (expressive or instrumental), which consumer recognized after using, related to consumer involvement toward clothing, 2) to clarify the effect of product performance on consumption emotion(positive or negative), 3) to investigate the effect of consumption emotion on satisfaction, and 4) to find out whether product performance had a direct effect on satisfaction toward product. The study was conducted in three steps. Through the two steps, measurement instruments were developed. At the last step, judgement sampling method were utilized to collect the data and subjects were 614 university students. Confirmatory factor analysis and structural equation model analysis were used to analyze the data. The results were as follows: 1) Consumer involvement had an effect on product performances but it was related to the expressive product performance more than to the instrumental product performance. 2) Product performance had positive influence on positive consumption emotion, while it had negative influence on negative consumption emotion. The results revealed that there were significant relationships between product performance and consumption emotion. 3) Positive consumption emotion had a positive effect on consumer satisfaction, on the other hand negative consumption emotion had a negative effect on consumer satisfaction. 4) Although the direct effects of product performances on satisfaction were larger than the indirect effects, product performance was greatly influential in consumption emotion and consumption emotion was strongly related to consumer satisfaction. Therefore, consumption emotion is an important determinant variable in the process of consumer satisfaction.

• 한국항만경제학회지
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• 제40권1호
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• pp.119-131
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• 2024

본 연구는 2018년부터 2022년까지 총 5개년의 전국 연안여객 항로 101개를 대상으로 연안여객 수요와 운임 간의 상관관계를 분석하고자 하였다. 이를 위해 패널 연립방정식 모형을 활용한 2단계 최소제곱추정법을 통해 개별항로의 특성 요인과 항로가 속한 지역적 특성 요인들이 연안여객 수송 실적과 운임에 미치는 영향을 분석하였다. 분석 결과, 내생변수인 운임과 외생변수 중 항로 특성 요인인 항로 거리, 도구 변수인 운항 횟수가 연안여객 수요에 영향을 미치는 것으로 나타났다. 그리고 단기 가격 결정 함수에서는 내생변수인 연안여객 수송 실적을 포함하여 외생변수 중 항로 특성 요인인 정원, 속력, 항로 거리가 연안여객 운임에 영향을 주는 것으로 나타났다. 본 연구는 연안여객과 관련하여 국내 연안여객 수요와 가격 결정에 유용한 시사점을 제공할 것으로 기대된다.

• 전기학회논문지
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• 제64권3호
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• pp.445-450
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• 2015

In the moving target problem, the velocity information of the moving target is very important as well as the high accuracy position information. To solve this problem, active researches are being conducted recently with combine the Time Difference of Arrival (TDOA) and Frequency Delay of Arrival(FDOA) measurements. However, since the FDOA measurement is utilizing the Doppler effect due to the relative velocity between the target source and the receiver sensor, it may be difficult to use the FDOA measurement if the moving target speed is not sufficiently fast. In this paper, we propose a method for estimating the position and the velocities of the target by using only the TDOA measurements for the low speed moving target in the indoor environment with sensor network. First, the target position and heading angle are obtained from the estimated positions of two attached transmitters on the target. Then, the target angular and linear velocities are also estimated. In addtion, we apply the Instrumental Variable (IV) technique to compensate the estimation error of the estimated target velocity. In simulation, the performance of the proposed algorithm is verified.

• 한국해양학회지:바다
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• 제27권4호
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• pp.173-193
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• 2022

해수 중 용존영양염은 지구온난화의 주요 원인인 대기 중 이산화탄소 조절에 관여하는 해양의 역할을 이해하기 위한 핵심변수이다. 우리나라에서는 한반도 주변 해역의 해양환경 변화를 지속적으로 감시하기 위해 국가기관의 정기적인 관측과 다양한 연구과제수행을 통해 용존영양염 자료가 수집되고 있다. 이들 자료의 활용도를 높이기 위해 각 기관들의 자료를 통합하는 관할 해역 해양정보 공동활용시스템(Jurisdictional Ocean Information Sharing System, JOISS)이 구축되었다. 본 연구에서는 JOISS 용존영양염 자료에 대해 한반도 주변해역의 용존영양염 지역 농도 범위와 용존영양염과 다른 해양학적인 특성 및 용존영양염 성분들간의 상호관계를 이용한 일차 품질관리를 수행 하였다. 지역 농도 범위와 일차품질관리를 통합한 품질관리 표식을 제공함으로써 자료의 신뢰도를 향상하여 JOISS 용존영양염 자료의 활용도 증가에 기여하고자 하였다. 또한 JOISS 용존영양염 자료의 국제적인 상호비교성 향상에 필수적인 이차품질관리 방법을 제안하였다.

• 한국기계가공학회지
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• 제10권4호
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• pp.1-7
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• 2011

The mode analysis of end-milling was introduced using recursive parametric modeling. Also, a numerical mode analysis of FRF in end-milling at different conditions was performed systematically. In this regard, a REIVM(recursive extended instrumental variable method) modeling algorithm was adopted and natural modes of real and imaginary part were discussed. This recursive approach can be used for the on-line system identification and monitoring of an end-milling for this purpose. For acquiring a cutting force, an experimental practice was performed. And these end-milling forces were used for the calculation of FRF(Frequency response function) and its mode analysis. Also, the FRF was analysed for the prediction of end-milling system. As a results, this algorithm was successful in each condition for the detection of natural modes of end-milling. After numerical analysis of the FRF, the tooth passing frequency was discriminated in their FRF, power spectrum and mode calculation.

• 웰빙융합연구
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• 제7권1호
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• pp.1-7
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• 2024

Purpose: The improvement of the social security system can greatly affect residents' future uncertainty, and it is important to study the relationship between public pensions and household consumption. Research design, data and methodology: Using the 2018 China Household Panel Survey (CFPS) data, the instrumental variable method is used to analyze the impact of pension insurance on urban residents' consumption. Results: The results of the study show that there are differences in the impact of three different pension insurance systems on household consumption. The pension insurance for public sector significantly boosts household consumption, and having a pension insurance for public sector can increase household consumption by 7.7%. The pension insurance for enterprise employee will reduce household consumption, but this is only significant for urban households. The pension insurance for urban and rural residents has a negative impact on household consumption. For the 16- to 39-year-old group, having a pension insurance for urban and rural residents will reduce household consumption by 5.7%. At the same time, household income, assets, scale, and education level will positively stimulate household consumption. Conclusions: The study reveals varying impacts among different pension types, highlighting the need for optimizing social security schemes to incentivize higher consumption rates.

• 아태비즈니스연구
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• 제15권2호
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• pp.159-180
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• 2024

Purpose - This study aims to examine the relationship between high-performance work systems and organizational ambidexterity. Additionally, it seeks to verify the mediating effect of organizational cultural diversity on this relationship. Design/methodology/approach - The study tested four hypotheses using data from manufacturing companies with more than 100 regular workers, sourced from the Human Capital Corporate Panel (HCCP). For empirical analysis, the generalized least squares (GLS) estimation method was employed, and the hypotheses were verified using a probabilistic effects model. Findings - The study revealed that high-performance work systems improve organizational ambidexterity by enhancing organizational cultural diversity. Research implications or Originality - This study confirms the mediating effect of organizational cultural diversity between high-performance work systems and organizational ambidexterity, explaining how high-performance work systems influence organizational ambidexterity through organizational cultural diversity. Additionally, it identifies an organizational cultural variable that closely aligns with the academic concept of organizational ambidexterity. The study demonstrates that the core elements of high-performance work systems are instrumental in cultivating an organization that simultaneously pursues seemingly competitive heterogeneous values.