• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.5
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• pp.605-612
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• 2019

Traditionally, travel demand forecasts have been conducted based on the data collected by a survey of individual travel behavior, and their limitations such as the accuracy of travel demand forecasts have been also raised. In recent, advancements in information and communication technologies are enabling new datasets in travel demand forecasting research. Such datasets include data from global positioning system (GPS) devices, data from mobile phone signalling, and data from call detail record (CDR), and they are used for reducing the errors in travel demand forecasts. Based on these background, the objective of this study is to assess the feasibility of CDR as a base data for travel demand forecasts. To perform this objective, CDR data collected for Daegu Metropolitan area for four days in April including weekdays and weekend days, 2017, were used. Based on these data, we analyzed the correlation between CDR and travel demand by travel survey data. The result showed that there exists the correlation and the correlation tends to be higher in discretionary trips such as non-home based business, non-home based shopping, and non-home based other trips.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.9
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• pp.947-955
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• 2002

In this paper, we derive an outage probability for the Erlang capacity and the link margin respectively, calculate them with the same parameters and outage probability, and then analyze a capacity and cell coverage in city, suburban, and open area. So, the Erlang capacity is more real than in a cell, and the cell coverage can be calculated with high reliability by the margin. When the $E_b/N_o$ decreases from 7 dB to 5 dB within the outage probability of 5 %, it is observed that the capacity is increased from 18 Erlang to 31 Erlang with the same margin of 2.8 dB, then the coverage is increased to 0.4 km, 1 km, and 2.5 km in city, suburban, and open area respectively. Also if the outage probability is decreased from 5 % to 2 % in case of $E_b/N_o$ of 5 dB, the result shows a very reliable link with additional increment of 0.88 dB in the margin and a high QoS (quality of service) within decrement of 0.15 km, 0.5 km, and 1.5 km for the same areas with decrement of 3 Erlang from 31 Erlang.

• Proceedings of the Korea Crystallographic Association Conference
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• 2002.11a
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• pp.11-11
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• 2002

K(H/sub 0.34/D/sub 0.66/)₂PO₄는 KH₂PO₄(KDP)의 수소원자를 중수소가 일부 치환한 결정이다. 실험에 사용한 시료는 KDP 원료시약을 중수(D₂O)에서 성장시킨 것으로, 단결정 구조해석을 통해 D와 H의 점유율을 정련하였다. 본 연구에서는 상전이에 따른 결정구조의 변화를 연구하기 위하여 한국원자력연구소의 연구용 원자로인 하나로에 설치된 고분해능 분말회절장치(HRPD)로 상온에서부터 10K 까지 온도를 변화시켜가며 회절패턴을 측정하였다. 그 결과 190-l95K 사이에서 상전이가 일어났으며, 이것은 DSC(Differential Scanning Calorimetry) 측정결과와 상온에서 단결정 분석결과 D의 점유도로 계산한 상전이 온도와도 잘 일치한다. 10K와 298K에서 측정한 회절패턴에 대해 프로그램 FullProf를 사용하여 각각 리트벨트 구조정련을 수행한 결과, 상온에서는 정방정계이며 공간군은 I-42d 이고 저온에서는 사방정계인 Fdd2로 변한다. 온도변화에 따른 핵밀도 분포를 측정한 결과 상온에서 D/H는 2회 대칭축을 중심으로 50％ 점유도의 두 가지 가능한 위치를 갖는 무질서(disorder) 상태로 존재하나 온도가 내려갈수록 한 쪽으로 치우쳐 상전이 온도 아래에서는 하나의 산소와 결합하여 질서(order) 상태를 보이며 다른 하나와는 수소결합을 이룬다.

• Journal of the Korean Ceramic Society
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• v.44 no.3 s.298
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• pp.175-181
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• 2007

Molecular dynamics simulation (MD) of $(62-x)CaO{\cdot}38Al_{2}O_{3}{\cdot}xBaO$ glasses has been carried out using empirical potentials with the covalent term. The simulations closely reproduce the total neutron correlation functions of glass with 5 mol% BaO and physical properties of these glasses such as elastic constants. For these glasses, aluminum is tetrahedrally coordinated by oxygen, but there is a part of five-fold and six-fold coordination of aluminum. There are no major changes to the mid-range structure of glass, as barium is substituted for calcium. To predict the barium coordination number, we have used the bond valence (BV) theory and also compared the results of simulation with Bond valence. The coordination number for oxygen around barium atoms is close to 8 and the average distance of barium and oxygen is nearly 2.80 A. The viscosity of these glasses increases with the content of barium oxide substituted for calcium oxide.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.932-939
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• 1998

In this paper, we analyze the performance of a multicode-CDMA system which have been proposed for the multimedia communications. The performance of a multicode-CDMA system, providing good spectrum efficiency as well as serving various bit rates, is analyzed with multipath, frequency selective, slowly fading Rayleigh channel. Also the proposed scheme adopting RAKE receiver with MRC(Maximal Ratio Combine) is advantageous to multipath channel. For a practical channel modeling, the JTC(Joint Technical Committee) recommended channel model(JTC(AIR) 23-065R6) is applied to simulation. The proposed schemehas serial-to-parallel convertor which splits input data stream of 2 Mits/s into 20 branches o 100 kbits/s. From the result of simulation, the case of RAKE receiver with 3 fingers to reduce the system complexity required the relatively large $E_{b}/N_O$ of 0 dB~1.5 dB, compared to the case of RAKE receiver with the number of path finger to keep the average error rate to be $1{\times}10^{-3}$ in channel A.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.150-154
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• 2005

본 논문에서는 LabVIEW program을 사용하여 크기가 다른 파이렉스 글라스 방전관의 오존 농도를 연속적으로 측정하여 특성을 분석하였다. 또한 Flux-2D program을 사용하여 파이렉스 방전관의 전계를 분석하였다. 실험 결과에 따르면 1[$\ell$/min]에서 가장 오존 농도가 높았으며, 파이렉스 글라스 방전관 I 에서는 약 62[g/$m^3$]. 파이렉스 글라스 방전관II 에서는 약 48[g/$m^3$]으로 나타났다. 또한 고압 펄스 전원에 따른 오존농도 변화를 3D분석을 통해 확인 할 수 있었다. 확인된 분석을 통해 오존농도를 요구하는 만큼 생성한다면, 에너지 손실을 감소시키고 전극 수병을 최대화 할 수 있다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.01a
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• pp.255-256
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• 2020

생산 현장에서 발생되는 다양한 형태의 데이터는 스마트한 제조관리를 가능하게 하는 원동력으로 이를 효율적으로 저장하고 처리, 분석하는 일련의 과정이 4차 산업혁명 기반의 제조혁신에 능동적으로 대응하기 위한 핵심요소로서, 이와 관련한 다양한 연구들이 활발히 이루어지고 있다. 특히, 제조데이터 분석이라는 영역은 단순하게 기존의 데이터를 통계적인 접근 수단으로만 보는 것이 아니라 다양한 산업별 업종 도메인의 특성에 기반하여 빅데이터 분석과 기계학습 등의 인공지능 모델로 발전하고 있다. 본 논문에서는 다양한 산업별 제조현장을 이해하는 도메인 경험 및 특성을 고려하여 데이터를 효과적으로 저장, 처리, 분석할 수 있는 클라우드 형태의 빅데이터 시스템을 제안한다.

• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.314-320
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• 2001

In this paper, the properties of an expansive agent (CaO-CaS $O_4$) for dry shrinkage compensation were investigated by a series of experimental program, which might be used at On-Dol heating system as mortar type. The expansion principle of the CaO-CaS $O_4$ was mainly verified. As a result of this study, the correlation between the content of the expansive agent and the compressive strength was obtained in the form of exponential function(Y = A $e^{-x}$), showing that as the content of expansive agent increased as the expansion performance with the compressive strength increased by only a certain amount. Also, as a results of the analysis of a correlation between the expansive performance and the chemical properties which generally accompanied a part of quality management in manufacturing the expensive cement, the expansive performance was relative to only the contents of the F-CaO among chemical properties(Blaine, +44$\mu\textrm{m}$R, F-CaO, S $O_3$,L.O.I). And it was clarified that the results were relative to the second order function, showing that if the contents of the F-CaO increased the expansive performance Increased.d.

• Journal of IKEEE
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• v.26 no.2
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• pp.329-332
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• 2022

In this paper, retention characteristics of lateral charge migration according to parameters of 3D NAND flash memory to which ferroelectric (HfO₂) structure is applied and ∆V_th were analyzed. The larger the P_s, the greater maximum polarization possible in ferroelectric during Programming. Therefore, the initial V_th increases by about 1.04V difference at P_s 70µC/cm² than at P_s 25µC/cm². Also, electrons trapped after the Program operation causes lateral charge migration over time. Since ferroelectric maintains polarization without applying voltage to the gate after Programming, regardless of P_s value, polarization increases as P_r increases and the ∆V_th due to lateral charge migration becomes smaller by about 1.54V difference at P_r 50µC/cm² than P_r 5µC/cm².

• Journal of the Society of Cosmetic Scientists of Korea
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• v.43 no.4
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• pp.309-320
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• 2017

In this study, the antioxidative effects and component analysis of 50% ethanol extract, ethyl acetate fraction and aglycone fraction obtained from Annona muricata leaf were investigated. Free radical scavenging activities were performed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, total antioxidant capacities were estimated using luminol-dependent chemiluminescence assay and $^1O_2$ quenching effects were estimated. Free radical scavenging activities ($FSC_{50}$) of 50% ethanol extract, ethyl acetate fraction and aglycone fraction were 45.6, 29.8 and $18.0{\mu}g/mL$, and total antioxidant capacities ($OSC_{50}$) were 4.4, 1.1 and $2.8{\mu}g/mL$, respectively. As a result of $^1O_2$ quenching experiment, ethyl acetate and aglycone fraction showed similar activities to L-ascorbic acid used as a comparative control. The cellular protective effects of 50% ethanol extract on the $^1O_2-induced$ cellular damage of human erythrocytes were exhibited at concentration-dependent ($5-50{\mu}g/mL$). TLC and HPLC were used to analyse components in the ethyl acetate fraction and aglycone fraction of Annona muricata leaf. In ethyl acetate fraction, rutin (quercetin-3-O-rutinoside), kaempferol-3-O-neohesperidoside, nicotiflorin (kaempferol-3-O-rutinoside), p-coumaric acid were identified. In aglycone fraction, kaempferol was identified. These results suggest that the extracts of Annona muricata leaf have the applicability as antioxidant cosmeceutical ingredients.