• Proceedings of the KSR Conference
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• 1998.11a
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• pp.171-178
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• 1998

This paper proposes a new overmodulation strategy to give a better voltage utilization by tracking voltage vector along hexagon sides. This strategy enables the inverter to control both magnitude and angle of current. Therefore, the vector control using this strategy can lead to better output torque dynamics compared to the conventional slip frequency control with six-step voltage, which is widely used in the traction drive. In this strategy, the d-axis output voltage of a current controller to control the flux is conserved and the q-axis output voltage to control the torque is controlled to place the voltage vector on the hexagon boundary In case of overmodulation. The limited q-axis voltage is used for anti-windup of q-axis current controller. This paper also presents a new field weakening scheme which incorporate the proposed overmodulation strategy. In this scheme, the flux level is selected by both required current limit and the available maximum voltage along hexagon sides. The validity of the proposed overall scheme is confirmed by the computer simulations for a typical traction drive with a 210[㎾] induction motor.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.233-240
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• 1998

This paper presents a high efficiency low switching PWM technique for the propulsion system of Electric car. In order to achieve the continuous voltage control to six-step and a low harmonics with low switching frequency under 500㎐, the synchronous technique is combined with a space vector overmodulation and implemented by using DSP. Improved performance and a validation of proposed method is shown by the experimental results using a 1.65MVA IGBT VVVF inverter and inertia load equivalent to 160 tons electric cars.

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.04a
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• pp.444-449
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• 2006

6시그마 프로세스는 정의(Define), 측정(Measure), 분석(Analyze), 개선(Improve), 관리(Control)라는 다섯 스텝을 통하여 문제를 해결하고 성과를 달성한다. 이 다섯 단계 중에서 정의 단계는 프로젝트를 선정하고, 고객을 정의하고 프로젝트의 핵심 요인을 파악하며, 팀을 구성하고, 일정을 수립하는 일련의 과정으로서, 6시그마 활동전체의 방향을 제시하는 동시에, 이 활동이 그 조직에 얼마나 효과성이 결정되는 단계로서 6시그마 전 활동을 통하여 가장 중요한 단계라 할 수 있다. 6시그마 활동 중 정의 단계의 4 Step인 Project의 선정, Project의 정의, CTQ의 도출 및 선정, Project의 실행 계획은 프로젝트의 성공과 실패를 좌우하는 중요한 요인이다. 본 연구는 F사에서 수행했던 프로젝트를 대상으로 정의 단계의 각 Step마다 적정한 Activity에 따라 수행되었는가를 분석하여 F사의 6시그마 활동의 문제점을 조사하여 향후 6시그마 활동의 방향을 제시하려한다.

• Journal of Korean Society for Quality Management
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• v.50 no.3
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• pp.373-386
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• 2022

Purpose: This study proposes the application of Six Sigma management innovation method for more systematically enhanced execution of Quality by Design (QbD) activities. QbD requires a deeper understanding of the product and process at the design and development stage of the drug, and it is very important to ensure that no fault is fundamentally generated through thorough process control. Methods: Analyzing the background and specific procedures of quality improvement based on the drug design basis, and analyzing the key contents of each step, we have differentated and common points from the 6 Sigma methodology. We propose a new model of Six Sigma management innovation method suitable for pharmaceutical industry. Results: Regulatory agencies are demanding results from statistical analysis as a scientific basis in developing medicines to treat human life through quality improvement activities based on drug design. By utilizing the education system to improve the statistical analysis capacity in the Six Sigma activities and operating the 6 Sigma Belt system in conjunction, it helped systematically strengthen the execution power of quality improvement activities based on pharmaceutical design based on the members of the pharmaceutical industry. Conclusion: By using QbD Six Sigma, which combines quality enhancement based on pharmaceutical design basis and Six Sigma methodology suitable for pharmaceutical industry, it is possible to obtain satisfactory results both by pharmaceutical companies and regulators by using appropriate statistical analysis methods for preparing scientific evidence data required by regulatory.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1586-1592
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• 2017

Voltage sourced converter (VSC) based direct-current (DC) grid has the ability to control power flow flexibly and securely, thus it has become one of the most valid approaches in aspect of large-scale renewable power generation, oceanic island power supply and new urban grid construction. To solve the optimal power flow (OPF) problem in DC grid, an adaptive particle swarm optimization (PSO) algorithm based on fuzzy control theory is proposed in this paper, and the optimal operation considering both power loss and voltage quality is realized. Firstly, the fuzzy membership curve is used to transform two objectives into one, the fitness value of latest step is introduced as input of fuzzy controller to adjust the controlling parameters of PSO dynamically. The proposed strategy was applied in solving the power flow issue in six terminals DC grid model, and corresponding results are presented to verify the effectiveness and feasibility of proposed algorithm.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.2
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• pp.75-82
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• 2017

PURPOSE: The purpose of this study was to determine the effects of arm training in standing position on balance and walking ability in chronic stroke patients. METHODS: Sixteen chronic stroke patients were allocated equally and randomly to an experimental group (n=8) or a control group (n=8). All participants received 60 minutes of comprehensive rehabilitation treatment, the experimental group additionally received an arm training in standing position for 30 minutes, while the control group additionally performed a treadmill training for 30 minutes. These 30-minute training sessions were held three times per week for six weeks. Upper extremity function was assessed using Fugle-Meyer motor assessment function upper extremity (FMA-UE), balance was assessed using Berg balance scale (BBS), and walking ability (gait speed, cadence, step length, and double limb support period) was assessed using the GAITRite system. RESULTS: Improvement on all outcome measures was identified from pre-to-post intervention for both groups (p<.05). Post-intervention, there was a significant between-group difference on BBS, gait speed, cadence, step length, and double limp support period (p<.05). The experimental group exhibited greater improvement in the BBS (p=.01; z=-2.48), gait speed (p=.01; z=-3.26), cadence (p=.02; z=-2.31), step length (p=.01; z=-3.36), and double limb support period (p=.03; z=-2.84) compared to the control group. CONCLUSION: The findings of this study suggest that arm training in standing position may be beneficial for improving balance and walking ability of patients with chronic stroke.

• Nuclear Engineering and Technology
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• v.41 no.7
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• pp.885-892
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• 2009

This manuscript will discuss a numerical method where the six equations of two-phase flow, the solid heat conduction equations, and the two equations that describe neutron diffusion and precursor concentration are solved together in a tightly coupled, nonlinear fashion for a simplified model of a nuclear reactor core. This approach has two important advantages. The first advantage is a higher level of accuracy. Because the equations are solved together in a single nonlinear system, the solution is more accurate than the traditional "operator split" approach where the two-phase flow equations are solved first, the heat conduction is solved second and the neutron diffusion is solved third, limiting the temporal accuracy to $1^{st}$ order because the nonlinear coupling between the physics is handled explicitly. The second advantage of the method described in this manuscript is that the time step control in the fully implicit system can be based on the timescale of the solution rather than a stability-based time step restriction like the material Courant limit required of operator-split methods. In this work, a pilot code was used which employs this tightly coupled, fully implicit method to simulate a reactor core. Results are presented from a simulated control rod movement which show $2^{nd}$ order accuracy in time. Also described in this paper is a simulated rod ejection demonstrating how the fastest timescale of the problem can change between the state variables of neutronics, conduction and two-phase flow during the course of a transient.

• PNF and Movement
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• v.14 no.1
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• pp.23-32
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• 2016

Purpose: The purpose of this study was to determine the effects of a coordinative locomotor training program on the functional movement screen (FMS) scores of badminton players. Methods: The participants consisted of 31 badminton players who were randomly assigned to either an experimental group (n=15) or a control group (n=16), and engaged in exercise five times per week for six weeks. The experimental group engaged in coordinative locomotor training and the control group engaged in general exercise. An FMS kit (USA) was used to measure the following: FMS score, deep squat, hurdle step, in-line lunge, shoulder mobility, active straight leg raise, trunk stability push up, and rotary stability. Results: The FMS score, deep squat, hurdle step, in-line lunge, active straight leg raise, and trunk stability push up showed significant improvement in the experimental group (p<0.05). Conclusion: The coordinative locomotor training program was able to produce confirmation that functional movement screen scores change in the case of effective exercise interventions in badminton players.

• International Journal of Air-Conditioning and Refrigeration
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• v.11 no.4
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• pp.209-217
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• 2003

The term “energy saving is economical” is appropriate for the national view point and for design and assessment of one system, but not appropriate when choosing the system by comparing alternative systems in the early design step. Sometimes, non-energy saving system is more economical than energy saving system because of the price of electricity, gas or oil, which are used for operating the air conditioning system. Therefore, when designing a system, we should consider the efficient alternatives through economic assessment of energy saving method. However, research on non-operating number control of the system is not sufficient because it is more common to use operating number control of the system for most economic assessment of air conditioning systems. For this reason, this research can provide the economic operating number control method as basic design data. The data obtained through analysis of life cycle cost based on amount of yearly energy use, are produced by system simulation of HASP/ACLD/8501 and HASP/ACSS/8502 for six alternative heating$.$cooling systems based on seasonal air conditioning system, which is widely used for medium and large size office buildings in Busan.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.6
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• pp.841-846
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• 2014

The present study was conducted to determine whether the two-step time-restricted feeding improves the fattening traits of one-step time-restricted feeding in geese. Thirty-six 8-wk-old geese were allotted into one of three groups. Group R1 (the 1-step restricted feeding group) was allowed access to feed for 2 h in the morning from 8 wk to 14 wk of age. Group R2 (the 2-step restricted feeding group) was treated as Group R1, but was additionally fed for 2 h in the afternoon from 12 wk to 14 wk of age. Group C (the control group) was fed ad libitum from 8 wk to 14 wk of age. Feed intake and body weight (BW) were recorded daily and weekly, respectively. At 14 wk of age, the blood samples were collected to determine the fasting plasma levels of glucose, triacylglycerols and uric acid before sacrifice. The results showed that daily feed intake (DFI) was lower, feed efficiency (FE) was higher in both Groups R1 and R2 than in Group C, and daily gain (DG) in Group R2 was higher than in Group R1 during the whole experimental period (p<0.05). Group R1 exhibited lower abdominal and visceral fat weights in carcass than did Group C (p<0.05), and Group R2 was in intermediate. The fasting plasma glucose levels in Group C were higher, and triacylglycerol levels in Group R1 were higher, compared with the other groups (p<0.05). It is concluded that time-restricted feeding in the fattening period not only increases FE but reduces DFI, and the additional meal during the late fattening period improves the DG without the expense of FE in geese.