• Korean Institute of Interior Design Journal
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• v.26 no.3
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• pp.71-80
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• 2017

Korea is facing various social problems including single elderly household, increase in the number of disabled people and poverty rate and a difference in the proportion of males to females between urban areas and rural areas along with the advent of rapid aging society. Especially, the ratio of poor households in rural areas residing in housing which falls below the minimum housing level and most of them are in the dead zone of housing welfare. In addition, if it is impossible for them to move (relocate) to new housing, the house remodeling is the only measure for improving their housing welfare. However, we don't have enough prior relevant academic and practical experience, and house remodeling requires a series of process including prior planning construction and post-occupancy evaluation, but almost no fundamental research that provides relevant insight has been carried out. Therefore, the purpose of this study is to describe all field situations that occur in the whole customized house remodeling process for disabled female senior citizens living alone in a rural area. The remodeling process was classified into initial planning stage, field verification and adjustment stage and construction stage as the method to participate in the field directly, and any change in the remodeling plan and its causes at each stage were analyzed. As a result, some remodeling items were changed from the main viewpoint of participating parties before the beginning of construction and for reasons such as the deterioration level of housing site, limitation in building equipment and rearrangement of housing, etc., and the remodeling method and its details were developed. It was identified that constant change that occurred in the remodeling process resulted from 1) unique poor characteristics of existing housing and 2) physical condition of residents and their unique lifestyle characteristics that were two aspects required to be emphasized by customized remodeling.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10A
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• pp.1123-1130
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• 2004

This paper proposes the fast OVSF code generation method using the multi-stage spreading scheme based on the single code indexing scheme. The conventional OVSF indexing scheme based on the code-tree structure uses two numbers as the codeword indices, the layer number and the code number of the corresponding layer. However, the single code index number implicitly includes the information of the spreading factor as well as the code number. Since the binary representation of the single code indices shows the pattern of the codeword, the orthogonality between two different codewords can be determined by comparing their code indices instead of much longer codewords. The above useful property also makes the codeword can be generated directly kom its single code index. In this paper, the multi-stage spreading scheme is applied to generate the long code by spreading two shorter codewords with the appropriate code indices. The proposed fast code generation algorithm is designed for 3GPP UMTS systems and verified by the simulations.

• Korean Journal of Adult Nursing
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• v.16 no.3
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• pp.493-501
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• 2004

Purpose: The purpose of this study was 1) to classify the stage of adoption 2) to compare the decisional balance and confidence by stage of adoption 3) to identify factors influenced the stage of adoption for breast self exam. Method: A comparative study using a survey method with convenience sample of 143 women was used. Decisional balance and confidence was measured using the CHBMS-K. Stage of adoption for BSE was measured by a single item modified by the researchers based on the Rakowski et al (1992). Result: 1) The number of women in each stage of adoption for BSE was as follows; maintenance phase, 7.7% (n=11), action phase, 49.0% (n=70), contemplation phase, 35.0% (n=50) and pre- contemplation phase, 8.4%(n=12). 2) The mean difference in the decisional balance (F=4.32, p=.006) and confidence (F=13.85, p=.000) according to the stage of BSE adoption was statistically significant. 3) Prevention education and confidence accounted for 32% of variance in BSE. Conclusion: Assessment of decisional balance and stage of adoption for BSE can guide planning for cancer prevention education. We must educate women to have confidence in BSE. Further, it is important to urge women to continually practice BSE.

• Journal of Korean Society for Quality Management
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• v.18 no.1
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• pp.65-76
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• 1990

A lot-sizing model for multi-stage MRP systems is proposed, in which known demands must be satisfied. In this model, an approach with considerations of initial inventory and limited production capacity is involved. Most of the studies on the lot-sizing techniques for multi-stage material requirement planning systems have been focused upon two basic approaches. One approach is to develope an algorithm yielding an optimal solution. Due to the computational complexity and sensitivity of the optimal solution to the problem of lot sizing, heuristic approaches are often employed. In this paper, the heuristic approach is used by sequential application of a single-stage algorithm with a set of modified cost by the concept of multi-echelon costs. The proposed method is compared with an lot-sizing method(Florian-Klein Model) to prove its effectiveness by numerical examples.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2031-2039
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• 2015

In the LED lighting industry, the dimming function in the LED lamp is required by demands of many consumers. To drive this LED lighting, various types of power converters have been applied. Among them, an LLC resonant converter could be applied for high power LED lighting because of its high efficiency and high power density, etc. The function of power factor correction (PFC) might be added to it. In this paper, a dimmable single-stage asymmetrical LLC resonant converter is proposed. The proposed converter performs both input-current harmonics reduction and PFC using the discontinuous conduction mode (DCM). Also, the lower voltage stress across switching devices as well as the zero voltage switching (ZVS) in switching devices is realized by the proposed topology. It can reduce cost and has high efficiency of the driver. In addition, the regulation of the output power by variable switching frequency can vary the brightness of a light. In the proposed converter, one of the attractive advantages doesn’t need any extra control circuits for the dimming function. To verify the performance of the proposed converter, simulation and experimental results from a 300W prototype are provided.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.38-39
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• 2017

This paper proposes a new control method for an AC-DC Buck converter which is utilized as a front-end converter of a 2-stage high power density adapter. In the conventional adapter applications, 2-stage configuration shows higher power transfer efficiency and higher power density than those of the single stage flyback converter. In the 2-stage AC-DC converter, the boost converter is widely used as a front-end converter. However, an efficiency variation between high AC line and low AC line is large. On the other hand, the proposed conduction band control method for a buck front-end converter has an advantage of small efficiency variation. In the proposed control method, switching operation is determined by a band control voltage which represents output load condition, and an AC line voltage. If the output load increasesin low AC line, the switching operation range is expanded in half of line cycle. On the contrary, in light load and high line condition, the switching operation is narrowed. Thus, the proposed control method reduces switching loss under high AC line and light load condition. A 60W prototype which is configured the buck and LLC converter with the proposed control method is experimented on to verify the validity of the proposed system. The prototype shows 92.16% of AC-DC overall efficiency and 20.19 W/in 3 of power density.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.112-113
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• 2006

A stoichiometric mixture for $Cdln_2Te_4$ single crystal was prepared from horizontal electric furnace. The $Cdln_2Te_4$ single crystal was grown in the three-stage vertical electric furnace by using Bridgman method. The quality of the grown crystal has been investigated by the x-ray diffraction and the photoluminescence measurements. The (001) growth plane of oriented $Cdln_2Te_4$ single crystal was confirmed from back-reflection Laue patterns. The carrier density and mobility of $Cdln_2Te_4$ single crystal measured with Hall effect by van der Pauw method are $8.61{\times}10^{16}\;cm^{-3}$ and $242\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $Cdln_2Te_4$ single crystal obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;1.4750\;eV\;-\;(7.69{\times}\;10^{-3}\;eV)T^2/(T+2147)$.

• Journal of Power Electronics
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• v.7 no.2
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• pp.174-180
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• 2007

In this paper, a simple control method for two-stage utility grid-connected photovoltaic power conditioning systems (PCS) is proposed. This approach enables maximum power point (MPP) tracking control with post-stage inverter current information instead of calculating solar array power, which significantly simplifies the controller and the sensor. Furthermore, there is no feedback loop in the pre-stage converter to control the solar array voltage or current because the MPP tracker drives the converter switch duty cycle. This simple PCS control strategy can reduce the cost and size, and can be utilized with a low cost digital processor. For verification of the proposed control strategy, a 2.5kW two-stage photovoltaic grid-connected PCS hardware which consists of a boost converter cascaded with a single-phase inverter was built and tested.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.3
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• pp.147-154
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• 2004

This paper presents a procedure for analysis and design of a fine positioning stage, which has many applications in industries for machine tools, semiconductor, LCD and so forth. The stage considered here is based on a single module with 3 axes which is composed of flexures hinges, piezoelectric actuators and their peripherals. Through a series of analysis, the structural analysis model is simplified as a rigid body(the moving part) and springs(the flexures hinges). An experimental design procedure is applied to determine the dimension of flexures hinges. A sensitivity analysis on the notch positions is also performed to obtain a guideline of fabrication accuracy for the stage. An actual fine stage is made and verified through an experiment on the dynamic characteristics.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.5 s.236
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• pp.625-632
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• 2005

This paper describes the shape optimization of a stator blade in a single-stage transonic axial compressor. The blade optimization has been performed using response surface method and three-dimensional Navier-Stokes analysis. Two shape variables of the stator blade, which are used to define a stacking line, are introduced to increase an adiabatic efficiency. Data points for response evaluations have been selected by D-optimal design, and linear programming method has been used for an optimization on a response surface. Throughout the shape optimization of a stator blade, the adiabatic efficiency is increased to 5.8 percent compared to that of the reference shape of the stator. The increase of the efficiency is mainly caused by the pressure enhancement in the stator blade. Flow separation on the blade suction surface of the stator is also improved by optimizing the stator blade. It is noted that the optimization of the stator blade is also useful method to increase the adiabatic efficiency in the axial compressor as well as the optimization of a rotor blade, which is widely used now.