• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.5
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• pp.1154-1163
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• 2008

DAS and SCADA system are main systems, which operate and manage the power system by using computer and communication technology. But DAS and SCADA have been operated independently in Korea, so there was some time delay in the fault handling and live-line work. To improve that problems, studies on the interface between DAS and SCADA have been needed. From November 2005 to December 2007, the pilot project has been performed in KEPCO's branch offices, as a result, direct method will be applied widely all over the country until 2010 because the operation information of substation users want can be transmitted fast and it is possible to control 43RC directly although the expense for direct method is about 1.3 times larger than that for web method. To improve problems revealed during the pilot project, substation object to object communication method is proposed and interface database automatic generation and interface system diagnosis and logging functions are developed. Interface data point and communication data type are defined, substation single line diagram automatic generation or manual editing function, SCADA monitoring and controlling function, log data managing function are developed in SCADA HMI program. It is expecting to reduce the average time for each outage about 33% and to improve the reliability, efficiency of operation, execution of DAS from automatic load transfer under a fault, and to contribute to export project.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.689-695
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• 2010

The effect of the code conversion process of Korean script (Hangul), also known as words for numbers, was investigated using event-related potentials (ERPs) during mental arithmetic operations. Study subjects were asked to determine whether the arithmetic results of a given target stimuli were correctly matched. Visual inspection and statistics of mean ERPs showed stimulus type-dependent processing rather than task-dependent processing. Results of addition and multiplication tasks revealed that the overall temporal profiles of the Arabic numerals were similar to the Hangul words for numbers. The only exception to this observation was a delayed positive-slope peak occurring around 300 ms, which was likely related to the encoding process of Hangul words for numbers to Arabic-digits, defined as a 'transcoding-related potential.' Source analysis confirmed that the topography of different waveforms for the two conditions was attributed to a single dipole located in the left temporo-parietal area; this area is known to be involved in Hangul words for number processing. These results suggest that the initial processing for encoding words for numbers was followed by arithmetic operations without direct access of internal number representation. Korea Academia-Industrial cooperation Society. The Korea Academia-Industrial cooperation Society. The Korea Academia-Industrial cooperation Society. The Korea Academia-Industrial cooperation Society.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.1
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• pp.68-78
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• 2013

In this paper, we propose an early spectrum sensing(ESS) as an advance preparation for radio-access trial, which enables multi-mode terminals to access the most appropriate radio-access system in a cloud-conceptual base station system where multiple radio access technologies(RATs) coexist. Prior to a random access to one of RATs, a multi-mode terminal conducts a spectrum sensing over entire frequency bands of whole RATs, then select the RAT with the lowest sensing power, that is likely to have the most available spectrum. Thus, an access failure caused by that the selected RAT has no available radio spectrum could be avoidable in advance. In computer simulation, we consider as various RATs as possible. First, circuit and packet systems are taken into consideration. In addition, the packet systems are classified according to the feasibility of carrier aggregation(CA). In case of terminal, three modes are considered with circuit-only, packet-only, and multi-mode. Subsequently, packet traffic is classified into real-time and non-real-time traffic with three different tolerable delay levels. The simulation includes a call process starting with a call generation and ending up with a resource allocation reflecting individual user's QoS requirements and evaluates the proposed scheme in terms of the successful access probability, system access time, system balancing factor and packet loss probability.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.409-416
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• 1999

액체/고체 경계면에 레일레이각으로 초음파 pulse를 입사시키면 입사된 에너지의 상당 부분이 고체쪽으로 침투여 표면으로부터 약 1.5 파장 깊이 정도까지 에너지 분포를 가지고 고체 표면을 따라 전파하는 레일레 이파로 전환되며, 이러한 입사각에서는 기하학적인 거울 반사가 일어나지 않고 반사파의 중심이 Schoch 변위만큼 전방으로 이동되고, 또 입사 방향으로 후반 산란되는 초음파의 신호가 급격히 증가하는 현상이 관찰된다. 만일 고체에서 초음파의 감쇠가 산란에 의해 크게 영향을 받고, 레일레이각에서 고체 쪽으로 침투한 에너지의크기를 $E_0$라고 하면, 고체 표면과 표면 근처를 전파하는 레일레이파의 산란파 에너지, $E_S$는 Schoch 변위, ${\Delta}_S$와 산란에 의한 감쇠계수 ${\alpha}_S$에 비례하는 관계가 있음을 이론적으로 구하였다. 입사 방향으로 후방산란되는 초음파는 산란파의 일부이므로 후방산란 초음파 에너지, E_{Bs}도 이와 같은 관계를 가진다. 그러므로, 레일레이각으로 입사된 초음파의 후방산란 에너지, $E_{B_S}$ 산란체(e.g. grain)의 평균 크기, D와 주파수 f와는 레일레이 산란 영역과 Stochastic 산란 영역에 대해 각각 $E_{B_S}\;\propto\;D^{3}f^{3}$와 $E_{B_S}\;\propto\;D\;f$인 관계를 가지는 것으로 얻어졌다. 이것은 액체/고체 경계면에서 레일레이각으로 입사되어 레일레이파로 전환된 초음파가 다시 액체로 그 에너지를 누설하여 그 산란 영역이 Schoch 변위 내에서 일어나기 때문이며, 이러한 영향에 의해서일반적인 산란에서의 주파수 의존성과는 달리 각 산란 영역에서 그 지수는 1씩 작은 값을 갖는다.향에 따라 음장변화가 크게 다를 것이 예상되므로 이를 규명하기 위해서는 궁극적으로 3차원적인 음장분포 연구가 필요하다. 음향센서를 해저면에 매설할 경우 수충의 수온변화와 센서 주변의 수온변화 사이에는 어느 정도의 시간지연이 존재하게 되므로 이에 대한 영향을 규명하는 것도 센서의 성능예측을 위해서 필요하리라 사료된다.가지는 심부 가스의 개발 성공률을 증가시키기 위하여 심부 가스가 존재하는 지역의 지질학적 부존 환경 및 조성상의 특성과 생산시 소요되는 생산비용을 심도에 따라 분석하고 생산에 수반되는 기술적 문제점들을 정리하였으며 마지막으로 향후 요구되는 연구 분야들을 제시하였다. 또한 참고로 현재 심부 가스의 경우 미국이 연구 개발 측면에서 가장 활발한 활동을 전개하고 있으며 그 결과 다수의 신뢰성 있는 자료들을 확보하고 있으므로 본 논문은 USGS와 Gas Research Institute(GRI)에서 제시한 자료에 근거하였다.ऀĀ耀Ā삱?⨀؀Ā Ā?⨀ጀĀ耀Ā?돀ꢘ?⨀硩?⨀ႎ?⨀?⨀넆돐쁖잖⨀쁖잖⨀／ࠐ?⨀焆덐瀆倆Āⶇ퍟ⶇ퍟ĀĀĀĀ磀鲕좗?⨀肤?⨀⁅Ⴅ?⨀쀃잖⨀䣙熸ጁ↏?⨀

• Journal of the Korean Geophysical Society
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• v.9 no.1
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• pp.37-45
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• 2006

Velocity structures were defined in the vicinty of the 140-m deep test borehole in the pungam basin through simultaneous inversion of surface seismic refraction and far-ofset VSP traveltime data. Seismicenergy generated at the surface by a seisgun was recorded both at 42 surface locations at 3-m intervalsalong the profiles in the N20E and its orthogonal directions and at 71 m depth in the borehole. Forthe ofset VSP study, seismic energy was generated by a 5 kg sledgehamer at the surface in the horizontal ofset range of -19.5∼+19.5 m from the borehole. The seismic signals were detected at 9∼99 m depths with 1∼2 m intervals and recorded for 204 ms per shot. After shot static corrections,first-arrival times picked from both the surface refraction and borehole records were simultaneouslyinverted to yield velocity tomograms. The tomograms indicate that a 1.5 m thick soil layer with velocities les than 500 m/s overlies basements having a velocity range of 3,067 ∼5,717 m/s. Within the basements,∼4 m and deeper than 71 m. The high-velocit yzones may be due to conglomerates intercalated with sandstones and siltstones. No evidence for large-scale fracture zones or faults is detected near the borehole

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4C
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• pp.331-340
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• 2006

In this Paper, we propose to extend the TSS-LS(Two-Step Search scheme with Linear search based Second step) scheme which was already proposed by the authors for coherent UWB(Ultra Wide Band) systems, to rapid and reliable acquisition of noncoherent UWB systems in multipath channels. The proposed noncoherent TSS-LS employing simple energy window banks utilizes two different thresholds and search windows to achieve fast acquisition. Furthermore, the linear search is adopted for the second step in the proposed scheme to correctly find the starting point in the range of effective delay spread of the multipath channels, and to obtain reliable BER(Bit Error Rate) performance of the noncoherent UWB systems. Simulation results with multipath channel models by IEEE 802.15.3a show that the proposed two-step search scheme can achieve significant reduction of the required mean acquisition time as compared to general search schemes. ]n addition, the proposed scheme achieves quite good BER performance for large signal-to-noise ratios, which is favorably comparable to the case of ideal perfect timing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.96-103
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• 2000

The voice traffic is one of the most important real-time objects in WATM(Wireless Asynchronous Transfer Mode) networks. In this paper, we propose a new MAC(Medium Access'Control) protocol for the efficienttransmission of voice traffic over WATM networks in the multimedia environment and compare the performanceto existing similar protocols. The new protocol separates the reservation slot period for voice and that for data toguarantee some level of QoS(Quality of Service) in voice traffic. This is denoted by a slot assignment functiondepending on the frame size. According to the characteristics of voice traffic which is repeatedly in silent states,the protocol allocates voice reservation request slots dynamically with respect to the number of silent(off state)voice sources and also sends the first block of talkspurt restarted after silent period with a reservation requestslot to reduce the access delay.The simulation results show that the proposed protocol has better performance than Slotted Aloha in bandwidthefficiency, and can serve a certain level of QoS by the given slot assignment function even when the number ofvoice terminals varies dynamically. This means we can observe that the new MAC protocol is much better thanthe NC-PRMA(None Collision-Packet Reservation Multiple Access) protocol.

• Fire Science and Engineering
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• v.30 no.5
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• pp.93-99
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• 2016

This study tested the combustion characteristics of veneer specimens coated with four kinds of ammonium salts. Each veneer specimen was coated three times with 20 wt.% ammonium salt solutions at room temperature. After drying, the combustion characteristics of the specimens coated with chemicals, were investigated using the cone calorimeter (ISO 5660-1, 2). The specimens coated with monoammonium phosphate (MAPP) and, diammonium phosphate (DMPP) showed a 6.7% and, 10.0%, lower mean heat release rate ($HRR_{mean}$), respectively, than that of the uncoated specimen. On the other hand, the specimens coated with MAPP showed a 15.7% higher $CO_{peak}$ production rate and the specimens coated with DAPP showed by 8.2% lower rate than that of the uncoated specimen. The veneer coated with ammonium sulfate (AMSF) and DAPP showed a 9.6% and 33.3% lower the peak smoke production rate ($SPR_{peak}$) than that of the uncoated specimen. In addition, the time to the peak smoke extinction area ($SEA_{peak}$) was delayed by 38.4% in the specimens coated with DAPP than the uncoated specimen. Therefore, DAPP inhibited the combustion properties of the veneer and showed a tendency to reduce smoke production.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.128-135
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• 2011

In this study, in order to develop ultra rapid hardening mortar(URHM) for tunnel repairs using bottom ash of low recycle ratio and Admixture as Eco concept, fundamental properties of URHM on temperature condition of construction field were performed. Test result, URHM of three types for fluidity and setting time were as in the following : B > C > A. Those for low temperatures were later than the standard condition. Compressive, bending and bond strength were similar with three types as follow. In compressive strength, initial strength of the low were smaller than the standard but the low in the long-term were similar with the standard. On the contrary to this, bending strength were similar in initial strength but the low in the long-term were smaller than the standard. The low in bond strength was average 35% less than the standard. Length changes was as in the following : A > C > B. the low is two times much as the standard but the case using blast furnace slag particles noticeably reduced length changes. Water absorption coefficient and water vapor resistance were as in the following : C > A > B. In case of URHM added bottom ash, water absorption coefficient and water vapor resistance were increased because bottom ash is porous material.

• Korean Journal of Food Science and Technology
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• v.37 no.4
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• pp.648-655
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• 2005

Effects of two types of formula designed for commercial product on forced-swimming capacity and related biochemical parameters of Sprague-Dawley rats were evaluated. Treatment groups were fed diet supplemented with 4.56% formula A (EFA: exercise-trained and formula A-supplemented group) or B (EFB: exercise-trained and formula B-supplemented group) for 4 weeks. All groups were regularly trained twice a week to be accustomed to swimming. After 4 weeks, each group was divided into two subgroups: 90 min swimming (90-min subgroups) and swimming until exhaustion (all-out subgroups). Serum was collected, and skeletal muscles were dissected out after swimming. Forced-swimming time until exhaustion was significantly longer (p<0.05) in EFA and EFB groups than that of exercised control group. Among 90-min subgroups, serum ammonia level of EFB group was significantly lower than that of exercised control group (p<0.05). Among all-out subgroups, serum lactate levels were not significantly different among exercised control and treatment groups, whereas serum-free fatty acid levels of EFA and EFB groups were significantly lower than that of exercised control group (p<0.05). In conclusion, EFA and EFB groups enhanced forced swimming capacity of rats by increasing fat utilization and delaying accumulation of serum fatigue factor.