• 한국콘텐츠학회논문지
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• 제11권10호
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• pp.93-107
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• 2011

우리나라의 경우 SO와 위성방송사업자는 직접사용채널을 운용할 수 있다. 그런데 직접사용채널을 어떠한 목적과 방식으로 운용할 것인지에 대해서는 방송법상 규정이 없다. 때문에 SO와 위성방송사업자는 직접 사용채널을 운용하지 않거나 운용하더라도 주로 수익채널로 활용하고 있는 실정이다. 이런 점에서 직접사용채널을 어떻게 운용하는 것이 바람직한가를 살펴보기 위하여 미국과 일본의 사례를 검토하였다. 미국의 경우 수익성 채널, 공동이용채널, 액세스 채널 등 다양한 성격으로 활용하고 있었다. 일본의 경우 지방자치 단체와 긴밀한 연계를 통해 지역소식과 이슈에 대한 여론을 형성하고, 지역행사를 안내하는 등 지역채널로 서의 성격이 강조되고 있었다. 우리나라의 경우 SO는 직접사용채널이 아닌 지역채널을 통해 일본과 유사한 성격의 지역채널을 운용하고 있고, 위성방송은 주로 자사의 수익을 목적으로 직접사용채널을 운용하고 있다. 이런 점에서 방송사업자의 자사 이익에 의해 운용하는 방식이 아니라 직접사용채널의 위상과 운용방안에 대한 심도깊은 논의를 통해 공익적 측면에서의 활용방안을 모색해야 할 것이다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2003년도 춘계학술발표논문집 (하)
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• pp.2117-2120
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• 2003

Trusted channel provides a means of secure communication and it includes security services such as confidentiality, authentication, and so on. This paper describes the implementation of trusted channel between secure operating systems that integrates access control mechanisms with FreeBSD kernel code[1]. The trusted channel we developed offers confidentiality an4 message authentication for network traffic based on the destination address. It is implemented in the kernel level of IP layer and transparent to users.

• International Journal of Fluid Machinery and Systems
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• 제3권4호
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• pp.379-385
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• 2010

We developed a high-efficiency, wide-operating-range centrifugal blower stage to meet the demand for reduced total energy-consumption in sewage treatment plants. We improved the efficiency of the two-dimensional impeller using a shape optimization tool and one-dimensional performance prediction tool. A limit of the throat deceleration ratio was set to maintain the stall-margin of the impeller. The low solidity vaned diffuser and return channel were designed using a sensitivity analysis with orthogonal arrays and three-dimensional steady flow simulations. The low solidity diffuser was designed in order to improve the performance in the low-flow-rate region. The return channel was designed so that the total pressure loss in the return channel was minimized. Model tests of both the conventional and optimized blower stages were carried out, and the efficiency and operating range of both stages were compared. The optimized blower stage improved in stage efficiency by 3% and in operating range by 5% compared with the conventional blower stage.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2097-2100
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• 2003

Many studies have been done on secure operating system using secure kernel that has various access control policies for system security. Secure kernel can protect user or system data from unauthorized and/or illegal accesses by applying various access control policies like DAC(Discretionary Access Control), MAC(Mandatory Access Control), RBAC(Role Based Access Control), and so on. But, even if secure operating system is running under various access control policies, network traffic among these secure operating systems can be captured and exposed easily by network monitoring tools like packet sniffer if there is no protection policy for network traffic among secure operating systems. For this reason, protection for data within network traffic is as important as protection for data within local system. In this paper, we propose a secure operating system trusted channel, SOSTC, as a prototype of a simple secure network protocol that can protect network traffic among secure operating systems and can transfer security information of the subject. It is significant that SOSTC can be used to extend a security range of secure operating system to the network environment.

• 정보보호학회논문지
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• 제14권3호
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• pp.3-12
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• 2004

보안운영체제는 운영체제에 내재된 보안상의 결함으로 인하여 발생할 수 있는 각종 해킹으로부터 시스템을 보호하기 위해서 기존 운영체제에 다양한 보안기능을 추가한 운영체제이다. 보안운영체제는 시스템 보안을 목적으로 고안되었으나 전체 시스템의 안전을 위해서는 네트워크 측면에서의 보안이 필수적이다. 이를 위해서 IPsec이나 SSL과 같은 네트워크 보안 프로토콜들이 개발되어 사용되고 있으나 정책이나 키 관리에 많은 주의를 필요로 하고 보안운영체제의 특성을 반영하기 어렵다. 본 논문에서는 보안운영체제 사이에서 안전한 통신을 제공하기 위한 간단한 신뢰채널 메커니즘을 소개한다. 본 신뢰채널은 네트워크 트래픽에 대해 기밀성과 인증 서비스를 제공하며, 보안운영체제에 사용되는 특정 보안정보를 전달할 수 있는 구조를 가진다. IP 계층의 커널 수준에서 구현된 신뢰채널은 단순한 처리구조를 통하여 신뢰채널 처리과정에서 발생할 수 있는 오버헤드를 줄일 수 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.129-130
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• 2006

As the research of wireless personal area network (WPAN) is more activated, various communication systems operating on 2.4Ghz are being developed. Systems such as Bluetooth, 802.11b, Zigbee and DBO-CSS are operating on 2.4Ghz. In addition to these communication systems, microwave oven resides in 2.4Ghz, so co-existance between each of these communication systems and microwave Oven is considered important factor of system performance. The effect of microwave oven on these communication systems is so critical that these systems are recommended to avoid the impact of microwave oven by allocation of different channel. In this paper, based on the DBO-CSS operating on 2.4Ghz, we propose a new algorithm of reducing the effect of microwave oven to develop robust communication system against microwave oven.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.687-689
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• 2004

As using of network increases rapidly, performance of system has been deteriorating because of the overhead and bottleneck. Nowadays, High speed I/O network standard, that is a sort of PCI Express, HyperTransport, InfiniBand, and so on, has come out to improve the limites of traditional I/O bus. The InfiniBand Architecture(IBA) provides some protocols to service the applications such as SDP, SRP and IPoIB. In our paper, We explain the architecture of IPoIB (IP over InfiniBand) and its features in channel based I/O network. And so we provide a performance evaluation result of IPoIB which is compared with current network protocol. Our experimental results also show that IPoIB is batter than TCP/IP protocol. For this test, We use the dual processor server systems and Linux Redhat 9.0 operating system.

• 한국수소및신에너지학회논문집
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• 제29권1호
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• pp.41-55
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• 2018

General polymer electrolyte fuel cell (PEMFC) operates at less than $80^{\circ}C$. Therefore liquid phase water resulting from electrochemical reaction accumulates and floods the cell which in turn increases the mass transfer loss. To prevent the flooding, it is common to employ serpentine flow channel, which can efficiently export liquid phase water to the outlet. The major drawback of utilizing serpentine flow channel is the large pressure drop that happens between the inlet and outlet. On the other hand, in the high temperature polymer electrolyte fuel cell (HT-PEMFC), since the operating temperature is 130 to $180^{\circ}C$, the generated water is in the state of gas, so the flooding phenomenon is not taken into consideration. In HT-PEMFCs parallel flow channel with lower pressure drop between the inlet and outlet is employed therefore, in order to circulate hydrogen and air in the cell less pumping power is required. In this study we analyzed HT-PEMFC's different flow channels by parallel computation using previously developed 3-D isothermal model. All the flow channels had an active area of $25cm^2$. Also, we numerically compared the performance of HT-PEMFC parallel flow channel with different manifold area and Rib interval against the original serpentine flow channel. Results of the analysis are shown in the form of three-dimensional contour polarization curves, flow characteristics in the channel, current density distribution in the Membrane, overpotential distribution in the catalyst layer, and hydrogen and oxygen concentration distribution. As a result, the performance of a real area fuel cell was predicted.

• 전기학회논문지
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• 제57권3호
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• pp.488-493
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• 2008

This paper represents a dual-mode type transmission technique for a high reliable narrow-band power line communication(PLC) modem, and its design and implementation of a system-on-chip(SoC). The proposed transmission technique is based on a Chirp modulation for the purpose of overcoming time variations of power line channel environments in the narrow-bandwidth of the frequency range of 95-145.5 kHz. The designed modem is fabricated utilizing a mixed 0.18 ${\mu}m$ CMOS technology. Especially, according to the power line channel environments the data transmission rate can be selectively changed into 2.5 kbps and 480 bps. The total hardware complexity of the implemented chip is about 50,000 gates, the power consumption is about 26mW, and the operating frequency is up to 5.12 MHz.

• 한국정보통신학회논문지
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• 제1권1호
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• pp.77-83
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• 1997

본 논문에서는 현재 디지털 이동통신 시스템에서 운용되고 있는 QCELP(Qualcomm Code Excited Linear Predictor) 음성부호화 방식과 향후 IMT-2000 (International Mobile Telecommunications 2000) 등의 시스템에서 사용 예정인 CS-ACELP(Conjugate Structure Algebraic Code Excited Linear Prediction) 음성부호화 방식과의 성능을 비교한다. 특히 무선 채널을 사용하는 이동통신환경의 특징인 채널에러로 인한 음성부호화기의 성능을 비교함으로써 채널에러에 강인한 음성부호화 알고리즘 설계에 대한 고찰을 유도한다.