• KDI Journal of Economic Policy
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• 제37권4호
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• pp.1-20
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• 2015

We examine the validity of popular exchange rate models such as the purchasing power parity (PPP) hypothesis and the monetary model for Korean won/US dollar exchange rate. Various specification tests demonstrate that Korean data are more favorable for both models based on time-varying cointegration coefficients as compared to those based on constant cointegration coefficients. When the abilities to predict future exchange rates between those models based on time-varying cointegration coefficients are compared, an in-sample analysis shows that the time-varying PPP (monetary model) has better predictive power over horizons shorter (longer) than one year. Results from an out-of-sample analysis indicate that the time-varying PPP outperforms models based on constant cointegration coefficients when predicting future exchange rate changes in the long run.

• 유통과학연구
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• 제18권11호
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• pp.69-77
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• 2020

Purpose: This research aims to verify the role of mobile shopping attributes, trustworthiness, and cultural dimensions on mobile shopping intentions in Saudi Arabia. The originality of the model stems from the verification of the moderating impact of cultural variables, namely collectivism and masculinity, and from the integration of trustworthiness as a variable depending on mobile shopping attributes. Research design, data and methodology: A survey was distributed to 233 consumers with different nationalities living in the Kingdom of Saudi Arabia. Structural equation modeling and multi-group analysis were carried out to verify the conceptual model and the moderating variables. Results: The findings support the influence of several innovation attributes, namely complexity and trialability on behavioral intentions, while relative advantage has a direct impact on trustworthiness. A few paths are moderated by masculinity and collectivism. Conclusions: Culture and mobile commerce attributes need to be thought out by managers as factors influencing mobile commerce segmentation for expatriates and locals. Trustworthiness is also a key factor of mobile shopping adoption. Limitations and future research ideas are presented to enrich the proposed model and improve its predictive validity.

• 전력전자학회논문지
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• 제5권6호
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• pp.592-600
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• 2000

본 논문은 직류측 센서만을 갖는 3상 PWM 정류기의 새로운 제어기법을 제안한다. 제어가 내부의 모텔전류와 시스템 전류의 편차를 영으로 제어하여 상전압의 크기와 위상을 추정하고 스위칭 상태와 직류링크전류로부터 상전류를 재구성한다. 제안한 상전압 빛 상전류 센서리스 기법을 PWM 정류기 시스템에 적용한 실험을 통하여 그 타당성을 검증하였다.

• ETRI Journal
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• 제28권2호
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• pp.182-190
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• 2006

The circuit modeling of interdigitated capacitors fabricated by high-k low-temperature co-fired ceramic (LTCC) sheets was investigated. The s-parameters of each test structure were measured from 50 MHz to 10 GHz, and the modeling was performed using these measured sparameters up to the first resonant frequency. Each test structure was divided into appropriate building blocks. The equivalent circuit of each building block was composed based on the partial element equivalent circuit (PEEC) method. Modeling was executed to optimize the parameters in the equivalent circuit of each building block. The validity of the extracted parameters was verified by the predictive modeling for the test structures with different geometry. After that, Monte Carlo analysis and sensitivity analysis were performed based on the extracted parameters. The modeling methodology can allow a device designer to improve the yield and to save time and cost for the design and manufacturing of devices.

• Journal of Electrical Engineering and Technology
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• 제7권1호
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• pp.51-57
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• 2012

This paper provides a safety guideline for DC supplied home appliances through the comparative analysis of existing safety guideline for AC supplied home appliances. For this purpose, a predictive DC home appliance model is suggested and in special international safety standards of AC appliances are also analyzed. Moreover, a DC distribution system is built to verify the validity of the proposed safety guideline. The detailed analyzing process is explained with help of informative experimental results.

• 전자공학회논문지B
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• 제32B권9호
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• pp.1239-1246
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• 1995

A forced commutated cycloconverter (FCC) is a direct ac-ac converter capable of providing simultaneous voltage and frequency transformations. In this paper, vector control of an induction motor controlling stator current with forced commutated cycloconverter is presented. The advantage of current control is that the stator dynamics are eliminated and high performance vector control can be achieved. A novel modulation method based on dq transformation techniques is presented. Proposed modulation strategy generates the low frequency modulation function by the instantaneous value of the desired output voltages not by the steady state values of output magnitude and output frequency. PI control and predictive control algorithm for current control are applied, and the validity of proposed method is confirmed through digital simulations. Simulation results of step response and torque distubance and current control are presented.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권4호
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• pp.272-281
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• 2000

This paper deals with the parallel operation of several numbers of PWM converters for a high speed railway train application. Several considerations are made to reduce the transformer interaction which can cause a current control problem in severe case. Also, in this paper, novel control strategy is proposed to achieve a harmonic free primary-side current control under a light load condition using one current sensor independent of the number of converters. In addition, the modified predictive current controller, which is suitable to a digital current controller with a relatively large sampling period, is used. Finally, to verify the system validity, digital control system with TMS320C44 micro-processor and small scale simulator are made and tested.

• ETRI Journal
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• 제45권4호
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• pp.713-723
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• 2023

Game bots are illegal programs that facilitate account growth and goods acquisition through continuous and automatic play. Early detection is required to minimize the damage caused by evolving game bots. In this study, we propose a game bot detection method based on action time intervals (ATIs). We observe the actions of the bots in a game and identify the most frequently occurring actions. We extract the frequency, ATI average, and ATI standard deviation for each identified action, which is to used as machine learning features. Furthermore, we measure the performance using actual logs of the Aion game to verify the validity of the proposed method. The accuracy and precision of the proposed method are 97% and 100%, respectively. Results show that the game bots can be detected early because the proposed method performs well using only data from a single day, which shows similar performance with those proposed in a previous study using the same dataset. The detection performance of the model is maintained even after 2 months of training without any revision process.

• 한국사회복지학
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• 제54권
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• pp.5-33
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• 2003

본 연구는 가족을 단위로 개입하는 사회복지 실천 및 연구 현장에 적합한 가족관계를 측정하기 위해 개발된 척도의 일반화 가능성을 검증하는 연구이다. 사회복지분야에서 2001년 개발된 "가족관계척도"를 도구로 하여, 이론적, 논리적 고찰을 통한 액면타당도 검증을 하였으며, 기혼자 집단 분석을 통한 실증적 타당도 검증을 하였다. 액면타당도를 위한 내용분석 결과 정서친밀요인은 긍정적 정서표현, 수용존중요인은 공감, 인정책임요인은 자율성과 유연성의 개념으로 타당도를 확인할 수 있었다. 실증타당도를 위한 분석결과는 구성타당도, 기준관련 타당도, 변별력으로 나누어 실시하였으며, 구성타당도를 위한 탐색적 요인분석에서 누적설명량은 54%, 각 하위요인별 문항들은 0.45 이상의 안정된 부하량을 보여주었고, 확인적 요인분석에서도 모형에 대한 부합지수가 높게 나타났다. 기준관련타당도 중 예측타당도를 위한 회귀분석과 판별분석 결과, 가족관계의 점수가 높을수록 가족스트레스 인식이 유의미하게 낮아지며, 가족스트레스 상 하위집단에서 유의미한 판별이 나타남을 확인하였다. 동시타당도를 위한 상관관계분석 결과 "가족관계척도"의 설명변인으로 부부(r=.54) 및 부모자녀간 의사소통(r=.64)이 가장 높은 긍정적 관계를 보인다. 삶의 만족 수준과 정신건강 수준도 가족관계 수준에 유의미한 긍정적 상관관계를 나타내 가족관계척도와의 수렴타당도를 설명하였고, 신체적 건강 수준은 가족관계 수준과 미약한 관계를 보여주어 가족관계척도의 판별타당도를 보여주는 근거로 검토되었다. 마지막으로 인구사회학적 특성에 따른 가족관계척도의 변별력을 살펴본 결과, 연령, 결혼형태, 경제적 수준, 학력에 대한 "가족관계척도"가 유의미한 차이를 보여주었다. 이상과 같은 연구결과는 대학생 집단을 통해 개발된 "가족관계척도"가 기혼자 집단에서 교차타당성(cross validation)이 확보됨을 보여주고 있으며, 이전 연구에서 밝히지 못한 다양한 기준관련 타당도와 인구사회학적 변별력을 통해 타당도의 일반화를 높였음을 보여주는 것이라 할 수 있다. 또한 사회복지분야에서 처음 개발된 "가족관계척도"가 가족을 대상으로 하는 사회복지연구 및 실천현장에서 사회측정도구(sociometric)로 활용되는데 있어 보다 실증적인 가능성을 제시한 것이라 할 수 있다.

• 한국의료질향상학회지
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• 제4권2호
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• pp.260-278
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• 1997

Background : Quality of professional nursing care is the most essential factor for survival and growth of nursing profession. Then, nursing professionals have responsibility for the evaluation of quality of professional nursing care. The purpose of this study was to develope an evaluation tool of nursing care for patients received gastrointestinal surgery with general anesthesia. This study was a primary work for the developement of a computer program for the evaluation of nursing care. Methods : This study was done through some consecutive steps. They were (1) Developement of items for the tool (2) Developement of an evaluation tool of nursing care quality for the G-I surgery patient (3) Test of reliability and validity of the tool. Two groups of experts and expert pannels who had much experience of the QA and the care of G-I surgery patients participated for developement of the items. 85 nursing records were used for the test of reliability and validity of the developed tool. The evaluation tools were developed with two types of scoring, norm-referenced tool and criterion-referenced tool. Results The system of items for tool was evaluation area evaluation item-indicator. There were 7evaluation areas which contained 32evaluation items which contained 7lindicators. Evaluation areas 1, 2, 3, 4 were for the evaluation of process and 5, 6, 7 were for the evaluation of outcome of nursing care for G-I surgery patient. For the test of interrator reliability, correlation coefficients of each scores of items and intragroup correlation coefficients were calculated. The average correlation coefficients between two rators were 0.65, 0.54 and the intragroup correlation coefficient were 0.99 and 1.00 by the types of scoring. The Cronbach alpha coefficients of the tools were 0.54 and 0.46 by the types of scoring. The average content validity index of the items was 0.95 from 4 pairs of experts. Because there were significant differences between some scores of quality of nursing care of 3 general hospitals regardless of the types of scoring, the tools could be thought to have some construct validity. And also, there were significant correlations between some scores of quality of nursing care and admission days and admission days after surgery regardless of the types of scoring, the tools could be thought to have predictive validity. Conclusion In this study, the evaluation tool of nursing care was developed for the very specified group of patient, G-I surgery patient. And the items were developed and tested by the experts of nursing practice. Because of these reasons, it was supposed that the tool could be used effectively in nursing pratice. And the procedures for the development and the test of the evaluation tool of nursing care in this study were supposed to be used for the developement of other tools.