• 한국시스템다이내믹스연구
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• 제8권1호
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• pp.97-115
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• 2007

In System Dynamics, causal maps are used as a tool for analyzing dynamic problems and discussing the outcome of analyzed problems. However there are some limitations to use causal maps. In the drawing phase of causal maps, the high abstraction of variables that constitutes problems makes it difficult to find out correct information. And principles or rules to check errors on causal maps are not sufficient yet. Moreover, simulation modeling tasks are required to be concerned separately from drawing causal maps because causal maps cannot provide enough information to simulation modeling. In order to overcome these limitations, this study shows ways that ensure validity, increase power of expression of causal maps and improve the connection between causal maps and simulation modeling.

• IEIE Transactions on Smart Processing and Computing
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• 제3권3호
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• pp.135-141
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• 2014

The inherent feature of the highly efficient spectrum usage has made Orthogonal Frequency Division Multiplexing (OFDM) preferable for Communication Standards. This study evaluated the performance of a Least Square (LS) estimator for a comb-type pilot insertion scheme over a fast fading Rayleigh channel. A High Peak-to-Average Power Ratio (PAPR) is one of the major downsides of the OFDM. The effects of an increase in the number of subcarriers on PAPR and the performance of the LS Estimator were studied. Increasing the number of subcarriers while keeping the pilots overhead constant resulted in improved performance of the LS estimator but the PAPR increased with increasing number of subcarriers. Therefore some trade-off between the number of subcarriers and the performance of the OFDM system is needed. The Mean Square Error (MSE) expression was also derived for the LS estimator in the case of a comb-type pilot arrangement. The MSE expression clearly explains the effects of the number of subcarriers on the performance of the LS estimator.

• 천문학회지
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• 제27권2호
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• pp.191-201
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• 1994

We propose to use the entropy of power spectra defined in the frequency domain for the deconvolution of extended images. Spatial correlations requisite for extended sources may be insured by increasing the role of power entropy because the power is just a representation of spatial correlations in the frequency domain. We have derived a semi-analytical solution which is found to severely reduce computing time compared with other iteration schemes. Even though the solution is very similar to the well-known Wiener filter, the regularizingng term in the new expression is so insensitive to the noise characteristics as to assure a stable solution. Applications have been made to the IRAS $60{\mu}m\;and\;100{\mu}m$ images of the dark cloud B34 and the optical CCD image of a solar active region containing a circular sunspot and a small pore.

• 간호행정학회지
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• 제4권1호
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• pp.215-228
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• 1998

The purpose of this study is analysis of 52 dissertations on assertiveness training which presented from 1982 to 1997 in Korea. It was diversified the research purpose to by 1) time of publication or presentation 2) research design, characteristics of subjects used in each study 3) related concepts, the effects of nursing interventions according to related concepts 4) the effects of nursing interventions according to the subjects 5) the effects of nursing interventions according to the frequency and the period of assertiveness training 6) the effects of nursing interventions according to the group size. 7) the effects of nursing interventions according to the necessary time per round. Findings obtained in the study were as follows : 1. At the point of the numbers of studies presented by year, the number of the studies tend to increase, especially the most plentiful papers were presented during five years from 1991 to 1995. 2. Research design of the studies belong to experimental research. The subjects of research consists of 5 Nursing related subjects and 47 Non-nursing related subjects so that Non-nursing related subjects contain much large proportion. 3. When studies were classified by the related concepts, they were classified that 17 studies were by assertiveness & assertive behaviour, 15 ones anxiety, 9 ones self & ego, 7 ones depression. It can be inferred that studies related to assertive behaviour, self & ego, sociality and power of learning were increasing. Otherwise, studies related to anxiety, depression, aggression, shyness and anguish were decreasing. 4. At the point of the nursing intervention effect by the subjects, the concepts of assertive behavior, feeling of self-respect and sociality were increasing, but the concepts of conflict and interpersonal stress were decreasing and the concepts of anxiety and sociality were ineffective in the subjects related Nursing. On the contrary, the concepts of assertive behavior, sociality and personalty were increasing, but the concepts of anxiety, depression, aggression, shyness, self-estranged feeling were decreasing and the concepts of assertive behavior, aggression, personalty, power of learning, anxiety, self-concepts and self-expression were ineffective in the subjects related Non-Nursing. 5. 18 studies can be found, which investigated 10 times for 5 weeks from the point of the nursing intervention effect by the times and the period of assertiveness training. In case of over 5 times of assertiveness training, assertiveness, assertive behavior and personality(tranquility, depression) increased. In 6 times, feeling of self-respect & egorespect increased but depression, interpersonal stress and anxiety decreased. In over 10 times, shyness, shame and feeling of self-estrangement decreased. In over 12 times, interpersonal anxiety decreased. 6. In the event of nursing intervention effect by the size of the group, it was greatest within 10 persons in 21 studies. In case of within 10 to 20, only feeling of self-expression were ineffective. Particularly, in case of over 31 persons, there were no ineffective concepts. 7. At the viewpoint of nursing intervention effect by the necessary time of one time, it was greatest within 1 to 2 hours in 32 studies. In case of within 1hour, aggression, power of learning and assertiveness were ineffective. In case of within 1 to 2 hours, assertive behavior, self-expression, personality and anxiety were ineffective. Particularly, in case of within 2 to 3 hours, there were no ineffective concepts.

• Journal of Power Electronics
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• 제18권1호
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• pp.289-299
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• 2018

Electric-field coupled power transfer (ECPT) systems employ a high frequency electric field as an energy medium to transfer power wirelessly. Existing ECPT systems have made great progress in terms of increasing the transfer distance. However, the topologies of these systems are complex, and the transfer characteristics are very sensitive to variations in the circuit parameters. This paper proposes an ECPT system with a double-sided LC network, which employs a parallel LC network on the primary side and a series LC network on the secondary side. With the same transfer distance and output power, the proposed system is simpler and less sensitive than existing systems. The expression of the optimal driving voltage for the coupling structure and the characteristics of the LC networks are also analyzed, including the transfer efficiency, parameter sensitivity and total harmonic distortion. Then, a design method for the system parameters is provided according to these characteristics. Simulations and experiments have been carried out to verify the system properties and the design method.

• 한국의류산업학회지
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• 제24권3호
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• pp.315-324
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• 2022

This study aims to verify the sewing technology and the expression of the virtual garment program by comparing the appearance similarity between the real and the virtual power shoulder jacket. To this end, the H and the X silhouettes of the power shoulder jacket were selected as the reference designs. After making the reference designs into real jackets by applying the human body dimensions of women in their twenties, virtual avatars and jackets were produced using CLO 3D programs. The results showed that the H-type with only expanded shoulders and less design variation had a high similarity between the reference photo and real garment, the real and virtual garment, and the reference photo and virtual garment. The power shoulder jacket of the reference picture was well reproduced in the real and virtual garments. Conversely, the X-type jacket, which is a tight fit and has many design variations, showed somewhat low similarity in the circumference items and the basic construction line. Especially in tight-fitted power shoulder jackets, the fact that shoulder angles and the essential items for pattern making cannot be reflected in reproducing virtual models was found to be a limitation in increasing the similarity of virtual clothing. Furthermore, the sewing system gap between the real and the virtual clothing exposed a difference in the appearance of virtual clothing.

• 한국기계기술학회지
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• 제20권6호
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• pp.776-782
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• 2018

After CNN basic structure was introduced by LeCun in 1989, there has not been a major structure change except for more deep network until recently. The deep network enhances the expression power due to improve the abstraction ability of the network, and can learn complex problems by increasing non linearity. However, the learning of a deep network means that it has vanishing gradient or longer learning time. In this study, we proposes a CNN structure with MLP layer. The proposed CNNs are superior to the general CNN in their classification performance. It is confirmed that classification accuracy is high due to include MLP layer which improves non linearity by experiment. In order to increase the performance without making a deep network, it is confirmed that the performance is improved by increasing the non linearity of the network.

• Journal of Power Electronics
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• 제18권1호
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• pp.116-128
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• 2018

Conventionally, in order to reduce the ac components of the dc-link capacitors of the two-level Half-Bridge Voltage Source Inverter (HB-VSI), high dc-link capacitances are required. This necessitates the employment of short-lifetime and bulky electrolytic capacitors. In this paper, an analysis for the performance of low dc-link capacitances-based HB-VSI is presented to elucidate its ability to generate an enhanced fundamental output voltage magnitude without increasing the voltage rating of the involved switches. This feature is constrained by the load displacement factor. The introduced enhancement is due to the ac components of the capacitors' voltages. The presented approach can be employed for multi-phase systems through using multi single-phase HB-VSI(s). Mathematical analysis of the proposed approach is presented in this paper. To ensure a successful operation of the proposed approach, a closed loop current controller is examined. An expression for the critical dc-link capacitance, which is the lowest dc-link capacitance that can be employed for unipolar capacitors' voltages, is derived. Finally, simulation and experimental results are presented to validate the proposed claims.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권12호
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• pp.5936-5954
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• 2018

Eight out of the top ten the largest technology companies in the world are involved in some way with the coming mobile VR revolution since Facebook acquired Oculus. This trend has allowed the technology related with mobile VR to achieve remarkable growth in both academic and industry. Therefore, the importance of reproducing the acoustic expression for users to experience more realistic is increasing because auditory cues can enhance the perception of the complicated surrounding environment without the visual system in VR. This paper presents a audio downmixing system for auralization based on hardware, a stage of sound rendering pipelines that can reproduce realiy-like sound but requires high computation costs. The proposed system is verified through an FPGA platform with the special focus on hardware architectural designs for low power and real-time. The results show that the proposed system on an FPGA can downmix maximum 5 sources in real-time rate (52 FPS), with 382 mW low power consumptions. Furthermore, the generated 3D sound with the proposed system was verified with satisfactory results of sound quality via the user evaluation.

• 한국콘텐츠학회논문지
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• 제6권11호
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• pp.161-171
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• 2006

색채는 시각이미지 표현의 중요한 조형요소로서 그 표현력이 증대되고 있다. 그러나 색채의 가변적인 특성과 함께 화면 내에서 조응하는 다른 조형요소와의 관계성은 색채의 효과적인 표현을 어렵게 한다. 디즈니사에서 제작된 <뮬란>과 <라이온 킹>에 나타난 그림스타일은 색채사용에 있어서 상당한 표현상의 차이가 있다. 두 작품의 색채사용에 대한 차이점과 그 원리를 규명하여 색채를 적절히 활용할 수 있는 방안을 세우고자 한다. 연구 방법으로는 색채가 가지고 있는 표현적인 특성을 다른 조형요소들과의 관계 속에서 어떻게 활성화시킬 수 있는가의 문제에 초점을 맞추었다. 결론적으로 색채는 빛의 속성 중 하나이지만 빛의 또 다른 속성인 밝고 어두움, 즉 콘트라스트(contrast)에 가장 큰 영향을 받는다는 것이다. 이것은 조형의 질서를 구축하는데 우선적으로 고려해야 할 사항 중 하나이다. 따라서 색채의 표현적인 특성을 강조하기 위해서는 다른 조형요소들과의 관계를 조절해야 하고 특히 명도와 형태의 표현적인 힘을 약화시켰을 때 가능해 진다.