• 조명전기설비학회논문지
• /
• 제18권4호
• /
• pp.181-187
• /
• 2004

3상 4선식 배전계통을 채용하는 우리나라는 비선형 부하의 증가로 중성선에는 많은 중성선 고조파 전류가 관측되고 있다. 또한 접지 임피던스는 고조파가 있는 중성선 전류에 영향 끼친다고 알려져 있다. 전위 강하법에 따라 현장에서 실측한 고조파 전류와 전압을 측정하고, Pattern Search 기법으로 고조파 해석용 접지 임피던스를 모델링 하였다. 여기서 구한 임피던스 모델은 현장 시험에 의한 임피던스 모델과 비교하여 유사한 결과를 얻었고, 접지 시스템의 고조파 및 과도 응답 특성을 평가하는데 활용될 것으로 사료된다.

• 전기학회논문지P
• /
• 제60권3호
• /
• pp.155-160
• /
• 2011

IPTV functions not only as media player that does play the broadcasting industry's contents, also as the gateway is guaranteed of QoS(Quality of Service). This is for free contents-sharing that device stores contents using home network circumstance, and is for watching with seamless network service. Also this have required next QoS model that can handle stably as it may contain more data of the small computing device in next generation home system. We need ubiquitous-oriented QoS's design and development project that focuses on internal and external media service, not the existing QoS nor one-sided QoS of media sevice industry. This paper focuses on network module development. This supports IPTV in media industry and two-way capability of QoS highlighting multimedia service in network industry. In additional, this can handle stably the multiplex signal of USN/RFID as the representative ubiquitous and home network that services high-speed wire and wireless interface, and support the seamless u-QoS.

• 한국대기환경학회지
• /
• 제18권1호
• /
• pp.51-58
• /
• 2002

Destruction process of toluene using a wire-cylindrical BBD (Dielectric Barrier Discharge) reactor packed with catalysts was investigated to characterize the synergetic effects of non-thermal plasma and catalyst process. The catalysts used in the present study were ${\gamma}$-Al$_2$BO$_3$ and Pt/${\gamma}$-Al$_2$O$_3$. Under the numerous test conditions, specific energy density (SED (J/L)) and the conversion of toluene, defined as (1 -[C$_{f}$]/[C$_{i}$]), were measured. The test results showed that toluene decomposition efficiency followed the pseudo-first order in the case of plasma only process. The pseudo-first order process, however, was modified to pseudo-zeroth order reaction in the case of catalyst-assisted plasma process. This modification of the reaction order was verified based on a simple kinetic model proposed in the present study. Owing to the modification of reaction order, which resulted from the catalytic process, the specific energy to achieve the high removal efficiencies, i.e. 80~90%, was reduced significantly.y.y.

• Computers and Concrete
• /
• 제18권1호
• /
• pp.53-68
• /
• 2016

In this study, an investigation is made from the statics and economic aspects of the possibility of using the composite material ferrocement on the surfaces of squat cylindrical grain silos. For this purpose, the geometry of two model silos, each of height 5 m and diameter 5 m and 12.5 m, was designed. Five different reinforced plates of 10 and 20 mm thickness were produced to research the most suitable ferrocement plates to be used on the surface of these silos. Most durable reinforcement type for covering the silo surface was determined by pressure and bending tests. Grade 30 and Grade 55 steel plates were also considered for use in covering steel-coated silos. In the statics analysis performed with SAP2000, the least plate thicknesses needed for silos surfaced with Grade 30 and Grade 55 steel were found to be 6.20 mm and 4.70 mm respectively for silos of diameter 5 m, and 6.70 mm and 5.00 mm for silos of diameter 12.5 m. In the economic analysis, it was found that 20 mm thick Type 4 (with a wire diameter of 0.30 mm and a mesh aperture of $2mm{\times}2mm$ square type) reinforced ferrocement surfacing material was 5.6-6.1 times more economical than Grade 30 steel surfacing material and 4.4-4.7 times more economical than using Grade 55 steel. These results show that ferrocement can be used in place of steel from the point of view both of statics and economy.

• Journal of information and communication convergence engineering
• /
• 제6권2호
• /
• pp.122-128
• /
• 2008

Multiprocessor architectures and platforms, such as, a multiprocessor system on chip (MPSoC) recently introduced to extend the applicability of the Moore's law, depend upon concurrency and synchronization in both software and hardware to enhance design productivity and system performance. With the rapidly approaching billion transistors era, some of the main problem in deep sub-micron technologies characterized by gate lengths in the range of 60-90 nm will arise from non scalable wire delays, errors in signal integrity and non-synchronized communication. These problems may be addressed by the use of Network on Chip (NOC) architecture for future System-on-Chip (SoC). We have modeled a concurrent architecture for a customizable and scalable NOC in a system level modeling environment using MLDesigner (from MLD Inc.). Varying network loads under various traffic scenarios were applied to obtain realistic performance metrics. We provide the simulation results for latency as a function of the buffer size. We have abstracted the area results for NOC components from its FPGA implementation. Modeled NOC architecture supports three different levels of quality-of-service (QoS).

• 융합보안논문지
• /
• 제5권3호
• /
• pp.15-22
• /
• 2005

인터넷의 보급과 다운사이징, SI 기법이 등장하면서 기존의 집중식 컴퓨팅은 급격히 분산 컴퓨팅으로 변하고 있다. 또한 분산 컴퓨팅은 유선으로 연결된 네트워크에서 벗어나 유비쿼터스 컴퓨팅으로 빠르게 변화하고 있다. 점차 복잡해지는 이기종 환경에서 용융 프로그램과 운영체제에 원만한 통신을 이룰 수 있게 하는 미들웨어로 CORBA가 널리 사용되고 있다. 그러나 지능적이고 다양화되는 공격들(해커, 바이러스, 웜 등) 속에서 분산처리 환경은 절대 안전할 수 없는 것이 현실이다. 본 논문에서는 OMG에서 제시한 CSS를 기반으로 유비쿼터스 환경에 적합한 DB보안 모델을 설계하고 기존 모델과 비교 분석하여 효율성을 제시하고자 한다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
• /
• pp.57-60
• /
• 2005

The objective of this paper is to investigate and analyze the behaviour of prestressed I section structural members constructed with ultra high perfomance steel fiber reinforced cementitious concrete (SFR-UHPC). This material is known as reactive powder concrete (RPC) mixed with domestic materials and its compressive strength is over 150MP. The parameters of test specimens were span to depth ratio, prestressing force, prestressing wire placement and web width. Most influential parameter to determine the failure mode between shear and flexural action was proved to be shear span ratio. The characteristics of ultra high-strength concrete is basically brittle, but due to the steel fiber reinforcement behaviour of this structure member became ductile after the peak load. As a result of the test, the stress block of compressive zone should be redefined. The proposed analytical calculation of internal force capacity based by plastic analysis gave a good prediction for the shear and flexural strength of specimens. The numerical verification of the finite element model which constitutive law developed for Mode I fracture of fiber reinforced concrete correctly captured the overall behaviour of the specimens tested.

• 대한치과의사협회지
• /
• 제54권2호
• /
• pp.134-141
• /
• 2016

Use of ready-made orthodontic appliance can lead to inefficiencies in the final stages of the orthodontic treatment. Because patients' teeth have anatomic variations, brackets that have been designed to fit on average tooth surface may result in positional discrepancies when leveling and alignment is completed. As a result, additional steps such as rebonding, wire bending and use of auxiliaries may be needed. Even in patients who have normal tooth anatomy and proper tooth size relationships, precise bracket placement is crucial in order to efficiently control the tooth positions. Digital models can provide advantages in clinical orthodontics as virtual tooth setup could be performed, and clinicians can easily visualize the predicted final occlusion. Through this setup model, customized brackets with individualized prescription and archwires that optimally fit with the patients' dental arches can be produced using CAD/CAM technology. Also, the brackets can be accurately placed with an aid of 3D-printed jigs. The purpose of this article is to introduce the commonly used labial and lingual customized orthodontic appliance systems using digital technology.

• 한국통신학회논문지
• /
• 제30권5B호
• /
• pp.324-329
• /
• 2005

전화망의 설비 제공에 따른 상호 정산 방식은 원가를 기반으로 하여 체계적이고 합리적으로 정착되어 있다. 기술의 발전으로 통신서비스는 음성과 데이터, 유선과 무선, 통신과 방송 등 다양한 산업 분야간을 결합하여 제공되고 있다. 따라서 광대역 통합 네트워크에서는 새로운 정산 방식이 필요하다. 본 고에서는 광대역 통신망에서 사업자간 상호 정산의 방법으로, 접속 대역속도와 전송거리 요소를 이용하여 접속 원가를 산정하는 방법을 제시하였다. 또한 광대역통합망의 계층별로 설비비용 가중치를 반영하여 다양한 서비스들에 대한 정산을 쉽게 하였다. 광대역통합망의 정산 모형으로서, 사업자간에 상호 접속 및 정산을 접속대역 속도계수와 이용거리계수로 표본화하여 효과적으로 반영하고자 하였다.

• 한국전기화학회:학술대회논문집
• /
• 한국전기화학회 2001년도 전지기술심포지움
• /
• pp.145-161
• /
• 2001

Novel characterization of thermal properties of a battery has been introduced by defining its frequency-dependent thermal impedance function. Thermal impedance function can be approximated as a thermal impedance spectrum by analyzing experimental temperature transient which is related to the thermal impedance function through Laplace transformation. In order to obtain temperature transient, a process has been devised to generate external heat pulse with heating wire and to measure the response of battery. This process is used to study several commercial Li-ion batteries of cylindrical type. The thermal impedance measurements have been performed using potentionstat/galvanostate controlled digital signal processor, which is more commonly available than flow-meter usually applied for thermal property measurements. Thermal impedance spectra obtained for batteries produced by different manufactures are found to differ considerably. Comparison of spectra at different states of charge indicates independence of thermal impedance on charging state of battery. It is shown that thermal impedance spectrum can be used to obtain simultaneously thermal capacity and thermal conductivity of battery by non-linear complex least-square fit of the spectrum to thermal impedance model. Obtained data is used to simulate a response of the battery to internal heating during discharge. It is found that temperature inside the battery is by one-third larger that on its surface. This observation has to be considered to prevent damage by overheating.