• Journal of IKEEE
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• v.13 no.4
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• pp.70-74
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• 2009

In this paper, We propose the visible light communication(VLC) link based on white light emitting diode (LED) and Photo detector(PD). The proposed architecture is demonstrated experimentally and its performance is verified through the experimental results of quality-factor(Q-factor) and eye pattern of 10Mb/s PRBS signal. The ambient light effect from a typical type fluorescent lamp source was also analyzed. when the distance between the LED and the PD is about 1m, error free wireless transmission of the LED was achieved up to 10Mb/s data rate. Under the condition with ambient light, low BER, data transmission of the VLC link is achieved up to 5Mb/s data rate at 1m. Also, when the PD is placed away from the center, low BER data transmission of the VLC link is achieved up to 1Mb/s at 10cm and 10Mb/s at 5cm.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.2
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• pp.83-90
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• 2010

The hydrodynamic interaction of two floating bodies in waves freely floating or connected by a rigid link is studied by using a boundary element method in the frequency-domain. The exact two-body hydrodynamic coefficients of added mass, wave damping and exciting force are calculated from the radiation-diffraction potential solution of the improved Green integral equation associated with the free surface Green function. The irregular frequencies in the conventional Green integral equation make it difficult to predict the physical resonance of the fluid in the gap between two bodies floating side by side. However, the improved Green integral equation employed in this study is free of irregular frequencies and always yields the exact solution of the multi-body radiation-diffraction potential boundary value problem. The 6 degree-of-freedom motions of two bodies freely floating side by side or connected parallel by a rigid link have been calculated for the incident wave frequencies ranging from 0.1 to 5 radians per second in head, left and right bow quartering seas. The 6-component load of the rigid link have also been presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.6
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• pp.561-566
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• 2017

The weight reduction design process of tension links could be studied based on the variation of tension, bending and torsional stiffness after substituting STKM11A steels with aluminum alloys (A356) with tensile strength of 245 MPa. The existed I-beam type link component may have a weak point for loads applied from a special direction. Therefore, it was investigated to the optimal shape of the link component that could withstand loads from all directions and at the same time reduce weight. Various types of link shapes were designed and analyzed, and the optimized shape was found. The optimized design can reduce over 40% of the original steel link weight, and it could be suggested for light-weight design guides and safe design conditions for the development of tension links.

• Journal of Advanced Navigation Technology
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• v.25 no.1
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• pp.84-89
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• 2021

The alternative method for symmetric configuration in optical link consisted of dispersion management and optical phase conjugation for compensating of the distorted optical signals due to chromatic dispersion and nonlinear effects of standard single mode fiber is proposed. The symmetric configuration means number of fiber spans, dispersion distribution in former half section and latter half section, etc should be symmetrical about optical phase conjugator. In dispersion-managed proposed in this research, optical phase conjugator is located after former half section consisted of 6 fiber spans and before latter half section of 14 fiber spans, and the averaged residual dispersion per span (RDPS) of each half section are consistence. The compensation effects of the distorted signals in the proposed link is analyzed by comparing with the results obtained in dispersion-managed link with the unequally averaged RDPS of each half section. From the simulation results, it is confirmed that RDPS deviation between adjacent fiber span has a grater effect on the compensation than the equivalent of the averaged RDPS.

• Korean Institute of Interior Design Journal
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• no.20
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• pp.91-97
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• 1999

Telecommuting becomes a new form of work according to the development of information technology. Therefore, the purpose of this study is to provide basic data for the interior space planning of telecommuting centers by means of surveying office workers' opinions. The major findings of this research are as follows. The opinion about whether to use telecommuting center if provided is showed highly positively. In the matter of space type of telecommuting center, 'mixing type I (open plan office but division with high partition)' is the most preferred, the next, is 'closed type'. The most preferred type of workstation is 'independent type', the next is 'X type' and the third is 'link type'. Preferred partition height is '1,300-1,500mm'. When planning telecommuting center, the most important element of space plan is 'size and layout of workstation' and the second is 'private space for confidential work'. In public workplace, the most important element 'refreshment space', and the second one is 'mailing system'.

• Proceedings of the Korean Institute of Interior Design Conference
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• 1999.04a
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• pp.27-30
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• 1999

Telecommuting becomes a new form of work according to the development of computer and telecommunication technology. Therefore, the purpose of this study is to provide basic data for the interior space planning of telecommuting centers by means of surveying office workers' opinions. The major findings of this research are as follows. The opinion about whether to use telecommuting center if provided is showed highly positively. In the matter of space type of telecommuting center, 'mixing type I (open plan office but division with high partition)' is the most preferred, the next is 'closed type'. The most preferred type of workstation is 'individual space type ', the next if 'X type' and the third is 'link type'. referred partition height is '1m300-1,500mm'.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.307-308
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• 2015

본 논문은 3-레벨 T-type 인버터의 새로운 중성점 전압 제어 기법을 제안한다. 3-레벨 T-type 인버터는 dc-link 전압을 커패시터 2개로 나누어 사용하며 두 커패시터간의 전압 차이로 인해 출력 전압의 왜곡을 야기한다. 공간 벡터 변조 기법으로 P-type과 N-type 전압 벡터의 스위칭 시간을 조절함으로써 복잡한 수학적 모델링 없이 중성점 전압을 제어하는 간단한 방식을 제안하였다. 제안된 중성점 제어 알고리즘을 설명하고, 10kW급 3-레벨 T-type 인버터 시제품을 제작하여 본 논문에서 제안하는 방식에 대한 타당성을 검증하였다.

• Bulletin of the Korean Mathematical Society
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• v.52 no.4
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• pp.1077-1095
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• 2015

In this paper we study equivariant crossed modules in its link with strict graded categorical groups. The resulting Schreier theory for equivariant group extensions of the type of an equivariant crossed module generalizes both the theory of group extensions of the type of a crossed module and the one of equivariant group extensions.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.238-242
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• 2005

This paper considers a routing problem on a RPR(Resilient Packet Ring). The RPR is one of the ring-type data telecommunication network. Our major problem is to find an optimal routing algorithm for a given data traffic on the network under no splitting the traffic service, where the maximum load of a link is minimized. This paper characterizes the Minmax problem and develops two heuristic algorithms. By using the numerical comparison, we show that our heuristic algorithm is valuable for efficient routing the data traffic on a RPR.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.288-292
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• 2001

In this paper, a maximum power control of a low-cost and rugged cage-type induction generator system is proposed, where the machine-side PWM converter is used for maximum power generation and field excitation control, and the line-side PWM inverter is used for the dc link voltage control and source-side power factor control. Simulation results through Matlab Simulink have been demonstrated.