• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.45-51
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• 2003

The ship's signal sound dispersed by air, obstacles, and noises due to absorption, reflection, and disturbances, respectively. It is one of the factors of marine casualties by misjudgment if receiving direction The last target of this study is to prevent inherent marine casualty using the analysis-evaluation techniques if the interferences of ship's signal sound. In this work, three-dimensional sound field control model is proposed to simulate various sound transmitting characteristics according to sea environments at sea The efficiency test of the model was carried out using VR-based ship simulator.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.2999-3004
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• 2010

In comparison with some other light sources, LED has merits such as long lifetime, pollution free, and high energy efficiency. Lately, due to development of LED with high brightness and capacity, LED, which has been applied in display system only, has applied in the field of lighting system. As power LED for lighting system can be burned out by heat problem, the driving current of power LED has to be controlled below the designed value. In this paper, power LED photovoltaic lighting system, which has the current limitting function, has been described. After photovoltaic power is generated from PV panel. it is charged into a battery. And then, after the charged power is converted to DC24[V] through a boost DC-DC converter, it is supplied to power LED at night. It has been validated by designing and testing of 72[W] power LED lighting system, which includes a PV charger, a boost DC-DC converter and a current limiter for driving power LED.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.11
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• pp.1754-1766
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• 1993

The application of VXIbus system, an Industry standard, is rapidly spreading with its ability to offer the easiness of integration from GPIB and the fast data transmission from VMEbus system. Compared with VXIbus Register Based Device, VXIbus Message Based Device has a drawback In the aspect of speed. But it is possible to utilize high level ASCII commands to control a Message Based Device, therefore system integration is much easier with Message Based Device than with Register Based Device. And, the FFT analyzer is an instrument for signal analysis which can be inexpensively implemented to be fast and have high resolution. Its wide ability of analysis presents numerous application. So, it is necessary to apply VXIbus system to FFT analyzer. In this paper, the implementation of FFT analyzer is performed using a DSP module and by implementing all A/D conversion circuit and a control module which performs VXIbus interface. The device can be controlled by Slot0 Commender which supports VXIbus Shared Memory Protocol through VXIbus.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.411-413
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• 2012

It is noticeable that the number of newly registered Android applications increases rapidly. Such a recent trend indicates the Android platform is spreading globally. The ongoing platform upgrade might be one of the main reasons of the popularity of the Android mobile platform. Android platform 4.0 or later provides WiFi-Direct APIs that allow smart devices to communicate with each other without intermediate media. In this paper, we propose design and implementation techniques for small-scale impromptu meeting applications based on WiFi-Direct. The proposed meeting application can be used in a situation when one is difficult to connect the Internet. It also provides meeting data sharing capabilities, noting functionality, real-time remote screen control, and grouping of meeting participants. Our development results have demonstrated that the Android WiFi-Direct APIs can be effectively applied to impromptu conferencing mobile applications.

• The KIPS Transactions:PartD
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• v.17D no.5
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• pp.359-370
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• 2010

As web 2.0 becomes one of the important architecture styles, more web applications adopt single page structure instead of multiple web pages and navigations between pages. A single page web application client, called a mashup client in this paper, interfaces more than one services and allows users to navigate in the page. A mashup client page includes complicated functions and has to handle various styles of services and user requirements, and therefore is usually developed manually. In this paper, we propose a model driven code generation approach for in-page navigations. We propose a page model and view navigation design approach, applying REST service architecture patterns. Then, we consider type conditions for each view to have service calls or navigation controls. Also, we developed an XForms page code generation system to demonstrate the efficiency of the proposed method. The developed system generates mashup client pages including navigation controls between services and views. This system can generate ready to use codes from service specifications, so this can help to reduce the development overhead. Moreover, our approach is based on formal model and navigation patterns so the generated result code is simple and easy to understand, and includes only the necessary controls. Therefore, the proposed approach can be more effective for the case of a large number of services.

• Journal of the Korean Society for Railway
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• v.14 no.6
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• pp.555-561
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• 2011

This paper is designed to propose methods to both analyze and control the reasons for cracks appearing during the construction of piers. For this aim, a numerical analysis was performed to identify the properties of crack which resulted from heat of hydration and differential drying shrinkage with the key influence factors considered. The results show that the thermal cracks occurred within a few days, and the drying shrinkage cracks within a few weeks. Meanwhile, settlement shrinkage cracks occurred within a few hours. Discussing the control methods based on the time of the cracks appearing, quality control, reduction of the unit quantity of cement, and the preservation of moisture on the surface are proposed as the realistic and effective methods for preventing settlement cracks, thermal cracks, and drying shrinkage cracks respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.8
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• pp.1790-1802
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• 1997

A wavelet transform coding method that fulfills the requirements of HD-VCR(high definition video casstte recorder) for studio applications in proposed. A constant bit rate is achieved by a forward rate control technique whcih determins the quantizer stepsize based on the coding results fo the previous frame. We also propose a two-level coder that consists of both the IDC(independently decodable code) and the DDC(dependently decodable code). To minimize error propagation, the transformed coefficients are restructured into transform blocks which are represented by a tree structure. The result shows thta the proposed coding scheme produces better picture quality with block effects than that of DCT(discrete cosine transform) based coding schemes at the same compression ratio. The proposed method meets most of the requirements of HD-VCR.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.1
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• pp.175-186
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• 1996

An optimal channel input-traffic control (OCIC) policy is proposed for slotted frequency-hopped spread-spectrum multiple access communication systems. When the number of channel input packets is set to the optimal number, the conditional throughput for the OCIC policy is analyzed. The state transition probability is derived, the steady state performance is analyzed, and the mean pracket delay is obtained. It is shown that the mean packet delay decreases considerably when the priority of transmission is given to backlogged users. The smaller is the number of requency slots, the larger are the differences between the preformance of the OCIC policy and that of the other policies.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2005.11a
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• pp.331-334
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• 2005

현재 무선 이동통신의 발달로 고속 신뢰성 높은 데이터 전송을 요구하고 있다. 그러나 무선 이동통신 환경은 데이터 전송 시 지연과 간섭 등에 의해 주파수 선택성 페이딩을 가진다. OFDM은 주파수 선택성 페이딩에 영향을 받는 통신 시스템에서 채용되는 강력한 기술이다. OFDM에 적응 변조와 함께 송수신기에 다중의 안테나를 설치함으로서 채널 지연 확산에 강력히 대응한다. 본 논문의 연구는 MIMO 시스템에 적용된 적응 변조를 가진 OFDM이다. OFDM 각 서브채널의 상태에 따라 최적의 비트값을 할당하고 전력을 제어한다. 본 논문에서 제안한 적응비트로딩 MIMO-OFDM 시스템을 사용하면 현재의 시스템보다 더 좋은 BER을 가지며 고속 통신할 수 있다.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 1999.10a
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• pp.213-220
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• 1999

최근 인터넷의 급속한 확산에 따른 전자상거래의 활성화는 조직과 규모 면에서 열세인 중소기업들의 판로 확장 및 홍보를 위한 새로운 대안으로 인식되고 있다. 그러나, 전자상거래 환경은 비약적으로 성장하고 있지만, 여전히 국내 중소기업들은 인력 및 자금의 상대적인 열세로 이러한 환경변화에 효과적으로 대응치못하고 있다. 본 논문은 이러한 문제를 해결하기위한 노력의 일환으로, 인터넷 상의 판매 에이전트를 지원할 수 있는 가상생산 에이전트(Virtual Manufacturing Agent)의 개발에 관한 내용을 담고 있다. 지금까지의 가상생산 시스템(Virtual Manufacturing Systme)에 관한 연구는 주로 설계, 공정, 제어 최적화에 그 초점을 두고 있으며, 가상생산 에이전트에 관한 연구는 이러한 문제를 지능형 에이전트 구조로 해결하고자 하였다. 본 논문에서는 이러한 기존의 연구와 달리 전자상거래 환경하에서 중소제조업체의 판매활동을 돕기 위한 판매에이전트를 실제 생산시스템과 연계하는 관점에서 가상생산 에이전트를 설계, 구현하였다.