• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.143-152
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• 2001

A method for miniaturization of microstrip patch antenna without degrading its radiation characteristics is investigated in this paper. It involves perforating the patch to form a microstrip square-ring antenna, and it's BW enhancement is investigated numerically and experimentally. A ring geometry introduces additional parameters to the antenna, and those are used to control impedances, resonance frequencies, and bandwidths. For a single square ring antenna, an increase of the size of perforation increases its input impedance, decreases the resonance frequency, and bandwidths. But it affects little on directivity of the antenna. To match the antenna to a transmission line and also enhance its bandwidth, the ring is stacked by a square patch or another square ring. Also numerically simulated results by the IE3D, and experimental data are compared for proof.

• Journal of Biomedical Engineering Research
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• v.23 no.5
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• pp.397-403
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• 2002

Urine glucose monitoring system is a self-monitoring system that display the glucose level by non-invasive measurement method. In this paper, We developed a noninvasive urine glucose monitoring system that improved defects of urine glucose measurement with a colorimeter method and invasive blood glucose measurement method. This system consist of bio-chemical sensor for urine glucose measurements, signal detecting part, digital and signal analysis part, display part and power supplying part. The developed bio-chemical sensor for the measurement of urine glucose has good reproducibility, convenience of handing and can be mass-produced with cheap price. To evaluate the performance of the developed system, We performed the evaluation of confidence about the detection of glucose level by a comparison between a standard instrument in measuring glucose level and the developed system using standard glucose solutions mixed with urine. Standard error was 2.85282 from the evaluation of confidence based on regression analysis. Also, In analysis of S.D(standard deviation) and C.V(coefficient of validation) that are important parameters to evaluate system using bio-chemical sensor, S.D was 10% which falls under clinically valid value, 15%, and C.V was under 5%. Consequently from the above results, compared to blood glucose measurement, the system performance is satisfactory.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.12
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• pp.1027-1035
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• 2016

In this study, a strain-controlled fatigue test of widely-used 316L stainless steel with excellent corrosion resistance and mechanical properties was conducted, in order to assess its fatigue life. Low cycle fatigue behaviors were analyzed at room temperature, as a function of the strain amplitude and strain ratio. The material was hardened during the initial few cycles, and then was softened during the long post period, until failure occurred. The fatigue life decreased with increasing strain amplitude. Masing behavior in the hysteresis loop was shown under the low strain amplitude, whereas the high strain amplitude caused non-Masing behavior and reduced the mean stress. Low cycle fatigue life prediction based on the cyclic plastic energy dissipation theory, considering Masing and non-Masing effects, showed a good correlation with the experimental results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1823-1830
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• 2003

This paper presents a multiple face detector based on a robust pupil detection technique. The pupil detector uses active illumination that exploits the retro­reflectivity property of eyes to facilitate detection. The detection range of this method is appropriate for interactive desktop and kiosk applications. Once the location of the pupil candidates are computed, the candidates are filtered and grouped into pairs that correspond to faces using heuristic rules. To demonstrate the robustness of the face detection technique, a dual mode face tracker was developed, which is initialized with the most salient detected face. Recursive estimators are used to guarantee the stability of the process and combine the measurements from the multi­face detector and a feature correlation tracker. The estimated position of the face is used to control a pan­tilt servo mechanism in real­time, that moves the camera to keep the tracked face always centered in the image.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.199-203
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• 1999

This paper is on the DSP system design and implementation for real time MPEG-2 AAC multichannel audio, and MPEG-4 object oriented audio coding. This DSP system employs two DSPs of the state of the art TMS320C6701, developed by TI semiconductor. DSP board has PCI interface for downloading application program and control the system. DSP board was designed to use for both encoder and decoder, by setting several switches. The system contains external input and output box also, for A/D and D/A conversion for eight channel audio. The input box converts multi channel digital audio to ADI format, that provides serial interface for eight channel digital audio. And the output box converts ADI format signal to multi channel audio. Through this ADI interface, DSP boards can be connected to input, output box. Implemented DSP system was tested for integration with MPEG-2 AAC encoder and decoder S/W. Currently the DSP system performs realtime AAC 4-channel audio encoding with two DSPs, and 8-channel decoding with one DSP.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.549-552
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• 2005

Multiple wireless devices in wired and wireless heterogeneous networks communicate with counterparts via a single access point (AP). In this case, the AP becomes a bottleneck of the network, therefore buffer overflows occur frequently and result in TCP performance degradation. In this paper, a new algorithm that prevents buffer overflows at AP and enhances TCP fairness is proposed. Depending on the buffer usage of AP, the new algorithm adaptively controls each TCP senders' transmission rate, prevents buffer overflows and thus guarantees improved TCP fairness. It is proved that the algorithm makes better of TCP throughput and fairness by preventing buffer overflows.

• Journal of Navigation and Port Research
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• v.34 no.5
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• pp.325-330
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• 2010

An open water rudder test was carried out to figure out the flow characteristics around a twin rudder at $Re=1.5{\times}10^4$. In the analysis, the unique characteristics of a twin rudder, which affects rudder forces, were explained. The analysis includes varying angles of attack from 10 to 30 degrees. In this paper, the measured results have been compared with each other to predict the performance characteristics of a twin rudder's 2-dimensional section by 2-frame grey level cross correlation PIV method. The length L=0.75C between upper and lower rudders could be defined as the critical length.

• Journal of Navigation and Port Research
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• v.31 no.10
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• pp.845-852
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• 2007

An OWC-type Wave Energy Conversion passes through 3 steps energy conversion process. This paper deal with the impulse turbine with staggered blade to improved performance by numerical analysis using commercial CFD code, FLUENT Maximum value of axial airflow velocity during exhalation is higher than that during inhalation This paper deal with special-type of Impulse Turbine so-called "Staggered Blade" for more efficiency to making air flow direct to on pressure side. Also, this paper has proposed special-type turbine with self-pitched blade more efficient.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2131-2139
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• 2014

In this paper, a binary-coded physical-layer network coding (PNC) is considered when high-order modulation techniques are used at source nodes in wireless communication environments. In the conventional PNC schemes, tight power control and phase compensation are required at a relay node. However, they may not be feasible in practical wireless communication environments. Thus, we do not assume the pre-equalization in this paper, and we only utilize the channel state information at receiver (CSIR). We propose a signal detection method for the binary-coded PNC with high-order modulation, such as QPSK and 16QAM, at the source nodes, while the conventional scheme only consider the BPSK at source nodes. We also analyze the bit-error performance of the proposed technique in both uncoded and coded cases.

• Journal of KIISE:Information Networking
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• v.29 no.1
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• pp.31-39
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• 2002

The VPN(Virtual Private Network) is a private network constructed logically on a public network infrastructure. There have been numerous studies to support the VPN services by using different technologies such as IP in IP, GRE, L2TP, MPLS and so on. Among these technologies, MPLS has shown many merits in aspects of QoS, security, and management, compared with other technologies. As an enhancement of the VPN that is controlled by MPLS PE(Provider Edge) routers, this paper presents the VPN controlled by MPLS CE(Customer Edge) routers. The functional architecture of the CE based VPN and operations of the CE routers are described along with the performance comparison of CE based MPLS VPN. It has been shown that the CE based VPN has more advantages than PE based VPN with respect to independency, scalability, security, and complexity.