• Title/Summary/Keyword: PC room

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A Study on the Development of Non-PC High-Early-Strength Concrete Without Steam Curing (증기양생이 불필요한 PC부재용 조강형 콘크리트 개발에 관한 연구)

  • Jun, Woo-Chul;Lee, Ji-Hwan;Park, Hee-Gon;Lee, Jae-Sam;Kim, Kyung-Min;Cho, In-Sung
    • Journal of the Korea Institute of Building Construction
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    • v.14 no.2
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    • pp.156-162
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    • 2014
  • This study aims to develop a rapidly hardening type of concrete to achieve the removal of form intensity (more than 10MPa) using the method of curing at room temperature in order to solve some economic environmental problems by omitting the steam curing process involved in producing PC (Precast Concrete). Therefore, this study evaluated a rapidly hardening cement containing a high amunt of C3S, which is very responsive in expressing early intensity, and a rapidly hardening type of concrete which uses some hardening accelerator to increase thehydration reaction of $C_3S$. The results of the experiment on concrete using some hardening accelerator are asfollows. In the slump flow experiment for identifying the liquidity and the air test, the desired values were met. The compression strength showed rapid expression response by 12 hours, and met the desired value within 6~9 hours. Its drying shrinkage value and Autogenous shrinkage value were measured as below ($-754.5{\times}10^{-6}$),and satisfied the requirements. In addition, in the Semi-Adiabatic Temperature Test, it was found that the concrete rose to its peak temperature within 24 hours and then its temperature dropped.

A Study on rural middle and high school students' Recognition Degree of harmful environment around Schools (지방소재 중 . 고등학생들의 학교주변 유해환경에 대한 인지도 조사연구)

  • 이명선
    • Korean Journal of Health Education and Promotion
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    • v.18 no.1
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    • pp.109-125
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    • 2001
  • The purpose of this study was to provide the basic data for establishing school education environment protection measures, on the basis of comparing and analyzing the realities and students' recognition degree of the environment and hygiene around the middle and high schools located in the rural areas. These study data were investigated by the self-administered questionnaires, taking as subject the 805 students in the middle and high schools located rural areas. And the results were as follows: First, as the result of having investigated the distribution degree of harmful environment within the purification zone around schools, it was found out that students responded: within the purification zone around the middle school, there were cartoon rooms (46.2%), electronic game rooms (45.9%), and singing rooms (45.0%). within the purification zone around the high school, there were electronic game rooms (46.3%), singing rooms (42.3%), billiard halls (41.4%), PC rooms (40.1 %), and Soju-room (35.2%). Secondly, as having analyzed student's recognition degree of the harmful environment around the school, it was found out that middle school students responded that sexual utensils-treating shops (3.74 points) were most harmful, and next corrupted bathhouses (3.52 points), and Soju-room (3.47 points), and high school students also responded relating to harmfulness in a similar sequence. Thirdly, in case of students' recognition degree of the harmful environment around the school according to general characteristics, 1) girl students had a higher ratio of recognition that the environment around the school was harmful than boy students (p〈0.001). 2) groups of students whose living standard was high had a higher ratio of recognition that the environment around the school was harmful than groups of students whose living standard was low (p〈0.05). 3) groups of students whose school was located near the park or the residential street had a higher degree of recognition that the environment around the school was harmful than groups of students whose school was located near the factory or the shopping area (p〈0.01). 4) groups of students whose school was located near the park or the residential street had a higher degree of recognition that the environment around the school was harmful than groups of students whose school was located near the amusement area or the shopping area (p〈0.05). Fourthly, 1) relating to the harmful shops where they experienced most highly the behavior of drinking and smoking, middle school students responded that they did so in the electronic game room (22.5%) and high school students did so in the singing room (31.4%), and high school students had a very high experience ratio of drinking and smoking, compared with middle school students (p〈0.001). 2) relating to the harmful shops where they could get in contact with lewd articles, both of middle school students (5.3%) and high school students (8.3%) responded that they could do so in the video room. 3) relating to the harmful shops where they experienced unsound opposite sex acquaintance, both of middle school students (5.8%) and high school students (16.6%) responded that they did so most highly in hotels, and high school students had a remarkably high experience ratio of unsound opposite sex acquaintance, compared with middle school students (p〈0.05). 4) relating to the harmful shops where they experienced violence, middle school students responded that they did so in the electronic game room (14.0%) and then in the singing room (3.7%), and high school students responded that they did so in the electronic game room (9.3%), the nightclub (4.6%), Soju-room (4.1 %), and high school students had a remarkably high experience ratio of violence, compared with middle school students (p〈0.05). 5) relating to the harmful places where they experienced drugs both of middle school students (0.8%) and high school students (2.4%) responded that they did so in the hotels. Fifthly, when going to the harmful shops, students had the experience of being guided and regulated roughly 1 time - 2 times, and middle school students (16.4%) and high school students (16.7%) had almost similar experience ratios of being guided and regulated. Conclusively, there was a limit in controlling the environment and purification zone only by legal regulations and institutional controls, the self-control purification effort for the school and the surrounding environment was required greatly, in order to protect students from harmful environment. In addition, the constant study to establish the educational environment purification measures must be carried out.

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A Study on Radiotechnologic Students' Satisfaction in Blended Learning (블렌디드 러닝 수업에 대한 방사선과 학생의 만족도 조사)

  • Park, Jeongkyu
    • Journal of the Korean Society of Radiology
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    • v.14 no.4
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    • pp.405-413
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    • 2020
  • Expectations and interests in blended learning are increasing as universities respond to the educational flow of transition to e-learning. This study analyzed the difference between the satisfaction of students in the first grade of radiology and the general characteristics of the subjects when applying blended learning. First, the satisfaction according to the class type was the highest in blended learning classes at 47.2%, followed by lecture room classes at 30.6% and remote classes at 22.2%. Second, the place where the remote lecture was watched by viewing the remote class according to the general characteristics was the highest at 94.4%. The most common medium for attending the remote class was using a PC, with 72.2%, and there was no significant difference in the remote class viewing method (p>0.05). Third, the appropriateness of the blended learning, "Remote lectures and lecture room lectures were properly conducted," had the highest score of 4.27±0.70. In addition, there was no significant difference in response to the teaching method according to gender and age (p>0.05). Fourth, the technology and system support,'Technical support and system support must be done when taking a remote lecture,' showed the highest score of 3.41±0.96. The lack of communication between professors and students,'In the remote class, communication between professors and students is insufficient' was the lowest with 2.88±1.00. In addition, there was no significant difference in the improvement of class according to gender and age (p>0.05). Through this study, it was intended to serve as a basis for the plans of blended classes and the policies of schools that introduced blended classes.

A Web Cache Algorithm for Small Organizations (소규모 기관을 위한 웹 캐쉬 알고리즘)

  • 민경훈;민경훈;장혁수;주우석
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.8A
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    • pp.1115-1123
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    • 2000
  • Most of the existing web caches are used in huge organizations. But many internet users belong to small organizations such as a venture company or a PC room. Users are in general in multiple window environments, and use several programs concurrently with rapid preference change within a relatively short period of time. We develop a network-path based algorithm. It organizes a cache according to the network paths of the requested URLs and builds a network cache farm where caches are logically connected with each other and each cache has its own preference over certain network paths. The algorithm has been implemented and tested in a real site. The performance results show that the new algorithm outperforms the existing algorithms in the hit ratio and response time dramatically with low cost.

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New Unsymmetric Dinuclear Copper(II) Complexes of Trans-disubstituted Cyclam Derivatives: Spectral, Electrochemical, Magnetic, Catalytic, Antimicrobial, DNA Binding and Cleavage Studies

  • Prabu, R.;Vijayaraj, A.;Suresh, R.;Jagadish, L.;Kaviyarasan, V.;Narayanan, V.
    • Bulletin of the Korean Chemical Society
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    • v.32 no.5
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    • pp.1669-1678
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    • 2011
  • Six new binuclear copper(II) complexes have been prepared by template condensation of the dialdehydes 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-l,4,8,11-tetraazacyclotetradecane (PC-a) and 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-l,4,8,11-tetraazacyclotetradecane (PC-b) with appropriate aliphatic diamines, and copper(II) perchlorate. The structural features of the complexes have been confirmed by elemental analysis, IR, UV-vis and mass spectra etc. The electrochemical behavior of all the copper(II) complexes show two irreversible one electron reduction process. The room temperature magnetic moment studies depict the presence of an antiferromagnetic interaction in the binuclear complexes. The catechol oxidation and hydrolysis of 4-nitrophenylphosphate were carried out by using the complexes as catalyst. The antimicrobial screening data show good results. The binding of the complexes to calf thymus DNA (CT DNA) has been investigated with absorption and emission spectroscopy. The complex [$Cu_2L^{1a}$] displays significant cleavage property of circular plasmid pBR322 DNA in to linear form. Spectral, electrochemical, magnetic and catalytic studies support the distortion of the copper ion geometry that arises as the macrocyclic ring size increases.

Health Risk Assessment of Occupants in the Small-Scale Public Facilites for Aldehydes and VOCs (일부 미적용 다중이용시설의 실내 공기 중 알데히드류 및 휘발성유기화합물 노출로 인한 건강위해성 평가)

  • Yang, Ji-Yeon; Kim, Ho-Hyun;Shin, Dong-Chun;Kim, Yoon-Shin;Sohn, Jong-Ryeul;Lim, Jun-Hwan;Lim, Young-Wook
    • Journal of Environmental Science International
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    • v.17 no.1
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    • pp.45-56
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    • 2008
  • This study was to assess the lifetime cancer and non-cancer risk of exposure of worker and user at public facilities in Korea to volatile organic compounds (VOCs). We measured the concentrations of two aldehydes and five VOCs in indoor air at 424 public buildings that 8 kinds of public facilities (70 movie theaters, 86 offices, 86 restaurants, 70 academies, 22 auditoriums, 30 PC-rooms, 30 singing-rooms and 30 bars) all over the country. There were estimated the human exposure dose and risks with averages of the using-time and frequency for facility users and office workers, respectively. Carcinogens (formaldehyde, acetaldehyde, and benzene) were estimated the lifetime excess cancer risks (ECRs). non-carcinogens (toluene, ethylbenzene, xylene, and styrene) were estimated the hazard quotients (HQs). The average ECRs of formaldehyde and benzene for facility worker and user were $1{\times}10^{-3}{\sim}1{\times}10^{-4}\;and\;1{\times}10^{-4}{\sim}1{\times}10^{-5}$ level, respectively, in all facilities. HQs of four non-carcinogens did not exceed 1.0 for all subjects in all facilities. The estimated ECRs for restaurant and auditorium were the highest, and the PC-room and bar were the next higher facilities. Furthermore, people in a smoking facility had the highest cancer risk. Higher ECRs of formaldehyde and benzene were observed in indoor smoking facilities such as restaurant and auditorium. Higher HQs of toluene and xylene were observed at the restaurant and office building.

The Evaluation of the Characteristics of Electromagnetic Waves on CFRTP for Multimedia Instrument Applications (Multimedia 기기에의 적용을 위한 CFRTP에 대한 전자파 특성의 평가)

  • ;Ri-ichi Murakami
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.8 no.3
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    • pp.254-263
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    • 1997
  • As the communication and electronic industry develops, it is important to study the electromagnetic shielding effectiveness (SE) of carbon fiber (CF) reinforced thermal plastics (CFRTP) against the electromagnetic (EM) radiation. In this paper the shielding effectiveness of CFRTP was measured experimentally in an electromagnetic shielding room. The resin ma- terials used were PC, PP, PEI, PMMA and PA. Experiments were carried out by using a copper box and a monopole antenna with a spectrum analyzer. From the experimental results it was found that CF was a good candidate as an electromagnetic shielding material. The sheilding effectiveness was found to be increased in the composite as the number of laminated layers of CF was increased. As the minor damage increased, the SE increased due to increasing of the plane density, transmitting thickness and reflected angle of the CF. Other characteristics of the SE depended on the material used for the resin matrix, distance of the antennas and the noise frequency band.

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Conceptual Design of PLS-II Control System for PLS (가속기 제어시스템의 성능향상을 위한 연구)

  • Yoon, J.C.;Lee, J.W.;Lee, E.H.;Ha, H.G.;Kim, J.M.;Park, S.J.;Kim, K.R.
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.1658_1659
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    • 2009
  • PLS(Pohang Light Source) will begin the PLS-II project that has been funded by the KOREA Government in order to further upgrade the PLS which has operated since 1992. The control system of the PLS-II has distributed control architecture, with two layers of hierarchy; operator interface computer (OIC) layer and machine interface computer (MIC) layer. The OIC layer is based on SUN workstation with UNIX. A number of PC-based consoles allow to remotely operating the machine from the control room. PC-based consoles use the Linux or Windows operation system. Similar consoles in the experimental hall are used to control experiments. The MIC layer is directly interfaced to individual machine devices for low-level data acquisition and control. MIC layer is based on VMEbus standard with vxWorks real-time operating system. Executable application software modules are downloaded from host computers at the system start-up time. The MIC's and host computers are linked through Ethernet network. It should enable the use of hardware and software already developed for specific light source requirements. The core of the EPICS (Experimental Physics and Industrial Control System)[1] has been chosen as the basis for the control system software.

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A Study on the Terrain Analysis using TIN & GRID-Based Digital Terrain Model (TIN과 GRID기반의 수치지형모델을 이용한 지형분석에 관한 연구)

  • 윤철규
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.16 no.1
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    • pp.67-74
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    • 1998
  • This paper performed terrain analysis using DTM(digital terrain model) with TIN/ GRID structure on PC environment. Contour layer from 1:5,000 scale map was used to produce DTM. DTHs were produced with and without considering breakline for each data structure. Processing time, file size, mean elevation and standard variation were analyzed for each DTM. slope map, aspect map were analyzed for grid structure with consideration of TEX>$5\times{5m},\;l0\times{10m},\;15\times{15m},\;l0\times{30m},\;45\times{45m},\;60\times{60m}$ cell size respectively. The results suggest following; The incorporation of breakline does improve mapping accuracy for highly disturbed landscape, Mean elevation doesn't increase as the grid size increases, while processing time, storage room is significantly lessened. Thus, the optimal grid size must be determined in advance for efficient application. slope decreases, while aspect increases as grid size is increasing.

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Thickness Effect of ZnO Electron Transport Layers in Inverted Organic Solar Cells

  • Jang, Woong-Joo;Cho, Hyung-Koun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.08a
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    • pp.377-377
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    • 2011
  • Organic solar cells (OSCs) with low cost have been studied to apply on flexible substrate by solution process in low temperature [1]. In previous researches, conventional organic solar cell was composed of metal oxide anode, buffer layer such as PEDOT:PSS, photoactive layer, and metal cathode with low work function. In this structure, indium tin oxide (ITO) and Al was generally used as metal oxide anode and metal cathode, respectively. However, they showed poor reliability, because PEDOT:PSS was sensitive to moisture and air, and the low work function metal cathode was easily oxidized to air, resulting in decreased efficiency in half per day [2]. Inverted organic solar cells (IOSCs) using high work function metal and buffer layer replacing the PEDOT:PSS have focused as a solution in conventional organic solar cell. On the contrary to conventional OSCs, ZnO and TiO2 are required to be used as a buffer layer, since the ITO in IOSC is used as cathode to collect electrons and block holes. The ZnO is expected to be excellent electron transport layer (ETL), because the ZnO has the advantages of high electron mobility, stability in air, easy fabrication at room temperature, and UV absorption. In this study, the IOSCs based on poly [N-900-hepta-decanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] (PCDTBT) : [6,6]-phenyl C71 butyric acid methyl ester (PC70BM) were fabricated with the ZnO electron-transport layer and MoO3 hole-transport layer. Thickness of the ZnO for electron-transport layer was controlled by rotation speed in spin-coating. The PCDTBT and PC70BM were mixed with a ratio of 1:2 as an active layer. As a result, the highest efficiency of 2.53% was achieved.

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