• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.805-810
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• 2004

The model is verified thorough simulations and experiments. And then the developed model is applied to a half car model and automobile vibrations are analyzed. The effects of tire design parameters on the automobile vibration energy are investigated. The results from laboratory and field tests confirm the validity of the analytical model. The 17-DOF half-car model is built to analyze the automobile vibration. The characteristics of the nonlinear model for a shock absorber are applied to this model. The results from the present 17-DOF half car model incorporating the analytical tire model with tire design parameters, are compared with a 5-DOF half car model where the tire is modeled with linear springs. The results of the 17-DOF model are closed to experimental results. Using the 17-DOF model, the influences of tire design parameter are considered. According to the results of analyses, the vibrations at seat/body/wheel are predicted by simulation and experiment.

• Journal of Electrical Engineering and Technology
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• 제3권4호
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• pp.584-592
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• 2008

In this paper, we propose a new model of the magnetic control force exerted on the levitation object in magnetic levitation systems. The model assumes that the magnetic force is a function of the voltage applied to an electromagnet and the position of a levitation object. The function is not explicitly expressed but represented through a 2D lookup table constructed from the experimentally measured data. Unlike the conventional model that reveals only local characteristics of the magnetic force, the proposed model shows global characteristics satisfactorily. Specially devised measurement equipment is utilized in order to gather the data required for model construction. An experimental procedure to construct the model is presented. We apply the proposed model to designing a sliding mode controller for a lab-built magnetic system. The validity of the proposed model is illustrated by comparing the performances of the controller adopting the conventional model with that of the controller adopting the proposed model.

• 대한조선학회논문집
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• 제42권2호
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• pp.98-104
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• 2005

The mathematical models of hydrodynamic force and moment acting on a ship at low speed range should be established differently from the ones at nominal cruising speed range since a ship moves with large drift angle or rotates in a stationary position. We modified widely used Yoshimura's cross flow model in order to apply the system identification method to estimate parameters in the model. The apparatus and the procedure of free running model test were suggested so that the parameters in the model be estimated. The validity of our proposing modified model and test procedure was confirmed by comparison with the results of simulated model test.

• 약학회지
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• 제41권1호
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• pp.38-47
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• 1997

Using a concentric cylinder type, rheometer. the steady shear flow properties of vaseline were measured over the temperature range of 20~70${\circ}$C. In this paper, the shea rate and temperature dependencies of its flow behavior were investigated and the validity of some flow models was examined. In addition, the flow characteristics over a wide temperature range were quantitatively evaluated by calculating the various material parameters. Main findings obtained from this study can be summarized as follows: (1) At relatively lower temperature range, vaseline is a plastic fluid with a yield stress and its flow behavior shows shear-thinning characteristics. (2) As the temperature increases, the value of a yield stress and the degree of shear-thinning become smaller, consequently, the Newtonian flow behavior occurs at a lower shear rate range. (3) At temperature range lower than 45${\circ}$C, the flow behavior shows much stronger temperature dependence, and a larger activation energy is needed for flow. (4) The Herschel-Bulkley model is the most effective one g$^3$ to predict the flow behavior of vaseline having a yield stress. The validity of the Bingham and Casson models becomes more available with increasing temperature. The flow behavior of vaseline at temperature range higher than 45${\circ}$C can be perfectly described by the Newton model.

• 대한간호학회지
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• 제49권4호
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• pp.398-410
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• 2019

Purpose: This study used a system dynamics methodology to identify correlation and nonlinear feedback structures among factors affecting adolescent cyberbullying victims (CV) in Korea and to construct and verify a simulation model. Methods: Factors affecting CV were identified by reviewing a theoretical background in existing literature and referencing various statistical data. Related variables were identified through content validity verification by an expert group, after which a causal loop diagram (CLD) was constructed based on the variables. A stock-flow diagram (SFD) using Vensim Professional 7.3 was used to establish a CV model. Results: Based on the literature review and expert verification, 22 variables associated with CV were identified and the CLD was prepared. Next, a model was developed by converting the CLD to an SFD. The simulation results showed that the variables such as negative emotions, stress levels, high levels of conflict in schools, parental monitoring, and time spent using new media had the strongest effects on CV. The model's validity was verified using equation check, sensitivity analysis for timestep and simulation with 4 CV adolescent. Conclusion: The system dynamics model constructed in this study can be used to develop intervention strategies in schools that are focused on counseling that can prevent cyberbullying and assist in the victims' recovery by formulating a feedback structure and capturing the dynamic changes observed in CV. To prevent cyberbullying, it is necessary to develop more effective strategies such as prevention education, counseling and treatment that considers factors pertaining to the individual, family, school, and media.

• 한국학교수학회논문집
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• 제9권3호
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• pp.405-424
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• 2006

본 연구는 수학 영재의 행동특성 검사 도구를 개발하는데 목적이 있다. 연구는 문헌 연구를 통해 수학 영재의 행동 특성을 추출하여 유목화한 후 측정변인으로 규정하였으며, 각각의 측정변인별로 문항을 개발하여 예비검사 과정을 통하여 최종적으로 51개 문항으로 구성된 검사 도구를 개발하였다. 기존에 영재교육을 받은 학생과 표준화된 수학 창의적 문제해결력에서 상의 10%와 교사 지명 학생 포함하여 424명을 연구 대상으로 본 검사를 실시하였다. 검사도구의 신뢰도와 타당도를 검증한 결과 높은 신뢰도(.95)를 확보하였으며 Rash 1모수 모형을 이용하여 내적 타당도를 검증하였다. 주성분 요인추출방법으로 요인을 추출하여 Varimax 방법으로 직각회전을 한 구인타당도 검증에서 일반적인 수학정신 능력 요인, 수학적 능력 요인, 정보 수집과 처리 능력 요인과 수학적 성향 요인이 추출되었다 따라서 본 연구에서 개발한 수학 영재 행동 특성 검사 도구는 신뢰도와 타당도가 양호하게 검증되었다고 볼 수 있다.

• 한국사회복지학
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• 제68권3호
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• pp.149-180
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• 2016

본 연구는 국내에서 PANSI(Positive and Negative Suicide Ideation) 척도가 청소년의 자살사고를 측정하는 도구로 활용될 수 있도록 타당도와 신뢰도를 검정하는 것이 목적이다. 이를 위하여 중학생 552명에게 한국어판 PANSI 척도를 중심으로 한 설문조사를 실시하여 자료를 수집하였으며, 수집된 자료를 통하여 PANSI 척도의 내적일관성 정도를 알아보았고, 관련척도(CES-D, BDI, RES, SWLS)들과의 상관관계분석을 통하여 준거타당도를 살펴보았으며, 확인적 요인분석을 통하여 PANSI 척도의 요인구조의 적합도 정도를 분석하였다. 본 연구의 주된 결과는 첫째, PANSI 척도의 내적일관성 Cronbach' ${\alpha}$는 .883으로 신뢰성이 비교적 높았다. 둘째, PANSI 척도는 Self-esteem 및 SWLS 척도와 유의한 부적상관관계, BDI, CES-D와는 유의한 정적상관관계가 나타나 준거 타당도를 일정 정도 확보되는 것으로 나타났다. 셋째, PANSI 척도의 확인적 요인분석 결과 2요인 모형이 적합하였으며 자료에 대해 66.0%의 설명력을 가지고 있는 것으로 나타났다. 이러한 연구 결과는 PANSI 척도가 국내에서 청소년 자살사고를 측정하고 나아가 선별하는 데 활용할 수 있는 경험적 근거를 제공하는 것이다.

• Journal of Korean Biological Nursing Science
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• 제20권1호
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• pp.11-19
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• 2018

Purpose: The purposes of this study were to perform items analysis using the classical test theory (CTT) and the item response theory (IRT), and to establish the validity and reliability of the Korean version of pressure ulcer prevention knowledge. Methods: The 26-item pressure ulcer prevention knowledge instrument was translated into Korean, and the item analysis of the 22 items having an adequate content validity index (CVI), was conducted. A total of 240 registered nurses in 2 university hospitals completed the questionnaire. Each item was analyzed applying CTT and IRT according to 2-parameter logistic model. Response alternatives quality, item difficulty and item discrimination were evaluated. For testing validity and reliability, Pearson correlation coefficient and Kuder Richardson-20 (KR-20) were used. Results: Scale CVI was .90 (Item-CVI range= .75-1.00). The total correct answer rate for this study population was relatively low as 52.5%. The quality of response alternatives was found to be relatively good (range= .02-.83). The item difficulty of the questions ranged form .10 to .86 according to CTT and -12.19 to 29.92 according to the IRT. This instrument had 12-low, 2-medium and 8-high item difficulty applying IRT. The values for the item discrimination ranged .04-.57 applying CTT and .00-1.47 applying IRT. And overall internal consistency (KR-20) was .62 and stability (test-retest) was .82. Conclusion: The instrument had relatively weak construct validity, item discrimination according to the IRT. Therefore, the cautious usage of a Korean version of this instrument would be recommended for discrimination because there are so many attractive response alternatives and low internal consistency.

• 한국콘텐츠학회논문지
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• 제18권12호
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• pp.218-228
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• 2018

본 연구의 목적은 치의학 임상실습 장면에서 활용이 가능한 가상현실 기반의 치아발치 교육콘텐츠를 개발하는 것이다. 이러한 목적을 달성하기 위해 '학습내용 분석-설계모형 도출-개발-타당도 검증-수정 및 콘텐츠 완성'의 단계를 거쳐 치아발치 실습용 교육콘텐츠를 개발하였다. 연구결과, 3D모델링을 적용하여 환자의 안면해부학적 모델을 구축하고, 치아발치 수술과정 시나리오를 바탕으로 가상현실 기술을 적용한 단계별 수술장면을 에니메이션으로 구축하였다. 개발된 콘텐츠에 대한 전문가 평가를 실시하였으며, 인터페이스 타당도(M: 4.81, SD: 0.72)와 내용타당도(M:4.66, SD: 0.71)를 검증한 결과 타당하게 설계된 것으로 분석되었다. 따라서 개발된 치아발치 실습용 교육콘텐츠는 치의학 전공생의 임상수행 능력을 향상시키는데 적절한 도구로 판단된다. 본 연구를 토대로 의료 분야의 다양한 실습장면을 지원할 수 있는 가상현실 기술 기반의 교육용 콘텐츠 개발 연구가 활성화되기를 기대한다.

• 지역사회간호학회지
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• 제31권4호
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• pp.416-426
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• 2020

Purpose: The aim of this study was to evaluate the validity and reliability of the Korean version of Short-form Health Literacy Scale (HLS-SF-K12) for Adults. Methods: The English HLS-SF12 was translated into Korean with forward and backward translation. Survey data were collected from 204 adults who visited two hospitals in Korea. Content validity, construct validity, and known-groups validity were evaluated. Cronbach's α for internal consistency and test-retest were used to assess reliability. SPSS 21.0 and AMOS 21.0 software were used for data analysis. Results: The HLS-SF-K12 was composed of 12 items, and three subscales (health care, disease prevention, and health promotion). The instrument explained reliable internal consistency with Cronbach's α for the total scale of .89, and .74~.81 for subscales. The model of three subscales for the HLS-SF-K12 was validated by confirmatory factor analysis (Normed χ2=2.14 (p<.001), GFI=.92, RMR=.04, RMSEA=.08, CFI=.94, TLI=.92, IFI=.94). The hypothesis testing which analyzed the differences in health literacy by age and education level was satisfied. Conclusion: The HLS-SF-K12 is a valid and reliable instrument for measuring health information comprehension for adults in Korea.