• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.6
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• pp.417-426
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• 2021

Recently, use of the precast concrete (PC) system, which can increase economy by minimizing field work, has rapidly increased. However, the PC system cannot exhibit structural performance under construction, specifically before integration between members. Furthermore, since it is difficult to secure the structural integrity of beam-column joints even after construction, the PC system is vulnerable to progressive collapse. In the PC system, various types of details for PC beam-column joints have been proposed, while the structural/construction details of PC system generally used in Korea differ from those of overseas PC systems. However, studies on the progressive collapse of the domestic PC system are limited. Thus, in this study, we investigated the structural/construction details of PC beam-column joints mainly used in Korea. Based on the investigation, for the prototype PC system with typical joint details, a nonlinear finite element analysis was carried out to evaluate its structural performance under progressive collapse. Further, a parametric study was performed, and the effect of the design parameters was investigated, to recommend a method to improve the progressive collapse resistance of the PC system.

• Steel and Composite Structures
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• v.30 no.6
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• pp.535-550
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• 2019

Prestressed concrete (PC) bridges using corrugated steel webbing have emerged as one of the most promising forms of steel-concrete composite bridge. However, their long-term behavior is not well understood, especially in the case of large-span bridges. In order to study the time-dependent performance, a large three-span PC bridge with corrugated steel webbing was compared to a similar conventional PC bridge to examine their respective time-dependent characteristics. In addition, a three-dimensional finite element method with step-by-step time integration that takes into account cantilever construction procedures was used to predict long-term behaviors such as deflection, stress distribution and prestressing loss. These predictions were based upon four well-established empirical creep prediction models. PC bridges with a corrugated steel web were observed to have a better long-term performance relative to conventional PC bridges. In particular, it is noted that the pre-cambering for PC bridges with a corrugated steel web could be smaller than that of conventional PC bridges. The ratio of side-to-mid span has great influence on the long-term deformation of PC bridges with a corrugated steel web, and it is suggested that the design value should be between 0.4 and 0.6. However, the different creep prediction models still showed a weak homogeneity, thus, the further experimental research and the development of health monitoring systems are required to further progress our understanding of the long-term behavior of PC bridges with corrugated steel webbing.

• Polymer(Korea)
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• v.35 no.6
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• pp.537-542
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• 2011

Fracture behaviors of polycarbonate (PC)/polyestrercarbonate (PEC) blends and their miscibility have been examined to find out the mechanism of ductilie-brittle transition of fracture behavior which would be a main governing factor on the thickness sensitivity of impact strength of PC. $T_g$ measurement showed that PEC with a carbonate content higher than 30 mol% was miscible with PC. In the notched Izod impact test of PC, ductile-brittle transition occurred in the range of 4 to 5 mm thickness. The impact strength of miscible PC/PEC5 blends ductile-fractured in the thin specimens decreased with increasing PEC5 content, which was in accordance with the decrease of elongation at break in tensile test. In the brittle fracture of the thick specimens, the impact strength was well correlated with the plastic zone size in the vicinity of the notch tip.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.798-803
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• 2018

In order to use Si as an anode material for lithium-ion battery, the particle size was controlled to less than $0.5{\mu}m$ and carbon was coated on the surface with the thickness less than 10 nm. The carbon fiber was grown on the Si surface with 50~150 wt%, and the carbon coating was carried out once again. The Si composite material was mixed with dissimilar metals to increase the conductivity, and graphite was mixed to improve cyclic life characteristics. The physical and electrochemical characteristics of composite materials were measured with XRD, SEM, TEM and coin cell. The discharge capacity of Si/PC/CNF/PC was lower than that of Si/PC (Pyrolytic Carbon)/CNF (Carbon Nano Fiber). However, the cyclic life of Si/PC/CNF/PC was higher. Initial discharge capacity of 1512 mA h g-1 at 0.2 C rate and initial efficiency of 78% were shown. It also showed a capacity retention of 94% in 10 cycles.

• Korean Journal of Pharmacognosy
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• v.40 no.4
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• pp.351-356
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• 2009

Many isoquinoline alkaloids including berberine lower dopamine content by reducing tyrosine hydroxylase (TH) activity and aggravate L-DOPA-induced cytotoxicity in PC12 cells. In this study, the effects of berberine on 6-hydroxydopamine (6-OHDA)-induced cytotoxicity in PC12 cells and on unilateral 6-OHDA-lesioned rat models were investigated. Berberine at 10-30 ${\mu}M$ did not affect cell viability in PC12 cells. However, berberine at concentrations higher than $50{\mu}M$ caused cytotoxicity at 24 h. Berberine (10-50 ${\mu}M$) also enhanced 6-OHDA (10-50 ${\mu}M$)-induced cytotoxicity at 24 h compared to 6-OHDA alone with an apoptotic process. In addition, treatment with berberine (5 and 30 mg/kg, i.p.) for three weeks showed a dopaminergic cell loss in substantia nigra of 6-OHDA-lesioned rats: 30 mg/kg berberine was more intensive cytotoxic. The levels of dopamine were also decreased by berberine (5 and 30 mg/kg) in the ipsilateral substantia nigra of 6-OHDA-lesioned rats. These results suggest that berberine aggravated 6-OHDA-induced cytotoxicity in PC12 cells and treatment with berberine (5 and 30 mg/kg) in 6-OHDA-lesioned rats also enhanced the degeneration of dopaminergic cell death and the decrease in dopamine levels in substantia nigra. Therefore, the long-term L-DOPA therapeutic patients with isoquinoline compounds including berberine may need to be checked for the adverse symptoms.

• Bulletin of the Korean Chemical Society
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• v.7 no.5
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• pp.338-341
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• 1986

Hydrocarbon solution of $Ir(PPh_3)_2(CO)OClO_3$ reacts with $Ph_2PC_6H_4$-o-CHO and 3-methyl-2-aminopyridinyl aldimine to yield ${\bar{Ir(Ph_2PC_6H_4-o-CO)}}\;(PPh_3)_2(CO)(H)ClO_4$(1) and ${\bar{Ir(NC_6H_6NC}}C_6H_5)(PPh_3)_2(CO)(H)ClO_4$(2), respectively. The compound $Ir(PPh_3)_2N_2Cl$ also reacts with $Ph_2PC_6H_4$-o-CHO and 3-methyl-2-aminopyridinyl aldimine to give ${\bar{Ir(Ph_2PC_6H_4-o-C}}O)(PPh_3)_2(H)Cl(3)$ and $Ir(NC_6H_5NCC_6H_5(PPh_3)_2(H)Cl(4)$, respectively. Compounds 1, 2, 3, and 4 were characterized by infrared, $^1H$ NMR, $^{31}p$ NMR, UV spectra, and conductivity measurements.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.1037-1040
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• 2003

본 논문에서는 LAN 상에서 유휴 PC 들을 연산에 활용하는 PC Cluster 시스템에 대해 연구하였다. 특히, PC 실습실에 있는 PC 들의 유휴시간(Idle time)대를 이용하여 Cluster 연산에 사용함으로써 별도의 전용 클러스터 시스템을 설치하기 위한 하드웨어 및 설치 공간이 필요로 하지 않는다는 장점을 갖는다. PC 실습실의 PC 들은 주간에는 주로 교육 및 실습에 사용되며 오후 6시부터 오전 9시까지의 실습에 사용되지 않는 유휴시간을 CPU-Intensive 한 작업들을 병렬로 수행하는 PC Cluster로 구성하여 저가격의 고성능 시스템을 구축할 수 있다. 그리고 특정 연산을 전담하는 노드들을 지정하고 이 노드들의 연산 결과를 인접한 다른 노드들에게 전달함으로써 연속적인 다음 연산을 적용할 수 있도록 파이프라인(Pipeline) 형태로 구성한다. 파이프라인 형태의 PC Cluster 에서 연산을 겹침(Overlapped)으로서 처리량(Throughput)을 높일 수 있다. LAN으로 연결된 PC 실습실의 PC 들은 인터넷상의 연산 자원들보다 안정되고 신뢰성이 있기 때문에 복잡한 보안 기법을 사용하지 않아도 된다. 또한 연산시간이 유휴시간으로 고정되어 있기 때문에 네트워크의 부하 및 노드의 부하를 고려하는 복잡한 부하균등화 기법이나 스케줄링 기법이 필요로 하지 않는다.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.79-79
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• 2000

In this Paper, the PC input device using MEMS gyros and accelerometer is newly developed, so that it can measure rotation rate and linear acceleration of the human body in space. In General, the human motion has 6 degree of freedom but 2 degree of freedom is enough PC monitor with 2D display. Therefore the simple method is proposed to achieve minimum degree of freedom. It is also applied to the PC mouse. This method can be expanded to the input device for internet set-top box or internet TV.

• The Journal of Korean Academic Society of Nursing Education
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• v.6 no.1
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• pp.7-22
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• 2000

The purpose of this study was to identified the level of the exposure to the PC Pornography and what's their post-exposure reactions to the PC pornography. The subjects were 423 middle school boys in Pusan. The survey was executed from July 12 through October 30, 1999. The collected data were analyzed by SPSS WIN using the %, mean, ANOVA. The results of this study were as follows: 1. 79.4%(336 boys) were exposed to the PC pornography. 46.3%(196 boys) answered that they experienced the published pornography prior to the PC pornography. 2. 78.5%(333 boys) answered that they had their PC in their homes. This ratio revealed the higher level of possession. 67.6% said that their PC were set in their own rooms. 57.9% of the subject answered they experienced the Internet Communications. 68.6% of the subject said that they tried PC communications once or twice in a week. 38.5% of the subject expressed that they used their own PC for 1-2 hours in a day. Most of them(82.7%) enjoyed the PC games or entertainment programs. 81.3% of the subject answered that their school performance didn't show the progress after the use of their own PC. 78.3% of the subject answered that they acquired information. 45.2% of the subject answered that they made their friend through the Internet communications. 78.7% of the subject answered that the time of family dialogue decreased. 70.7% of the subject answered that the time of their TV watching decreased. 3. As for their post-exposure reactions the subject who were exposed to the PC Pornography showed the point 2.93 in the item 'pleasure'. The point of 'sexual impulses' was 2.81. But the point of 'anxiety' was 2.75, the point of 'dislike or disgust' was 2.62, the point of 'guilty' was 2.59. 4. According to the frequency, the motivation and the companionship on the exposure to PC Pornography, their post-exposure reaction scores showed differences significantly. Finally, the post-exposure reaction had relation to the frequency, the motivation, the companionship and the place (F=3.28 ~ 8.40, p=.012 ~ .000).

• Bulletin of the Korean Chemical Society
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• v.19 no.5
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• pp.565-568
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• 1998

Novel mononuclear metal complexes with the formula $[M(Ph_2PC_6H_4NC_3H_6NC_6H_4PPh_2)]$ (M=Pd (1); M=Pt (2)) were obtained when N,N'-bis[2'-(diphenylphosphino)phenyl]propane-1,3-diamine, I was mixed with cisdichlorobis(diethylsulfide)palladium and platinum in the presence of NEt3. Two mononuclear metal compounds with the fomula [M(Ph2PC6H4NH)(SEt2)Cl] (M=Pd (3); M=Pt (4)) were synthesized from $M(SEt_2)2Cl_2$ and N-(2'-diphenylphosphinophenyl)-4-amino-1,1,1,5,5, 5-hexafluoro-3-penten-2-one, II by the elimination reaction of hexafluoro pentenone. The X-ray single crystal structures of 1 and 4 are described. X-ray single crystal diffraction analyses reveal that compound 1 is a mononuclear palladium compound with P,N,N,P-coordination mode and 4 is a mononuclear platinum compound with P,N-coordination mode.