• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.721-729
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• 2008

The purpose of this study is to investigate the engineering properties of concrete for the early strength development. As a result of reviewing it by establishing each experimental factor and level, the cement had more excellent quality performance in CHC and HESPC than OPC. This study has shown that the PC series admixture was more excellent in side of elapsed time (aging) and early strength development than PNS series admixture. In addition, there was much difference according to the curing temperature, but the early strength development showed the considerable vulnerability in curing temperature below $12^{\circ}C$. To satisfy the strength requirements of 5 MPa/18 hr this study has shown that it needed the curing temperature over $17^{\circ}C$ to the minimum in OPC, over $14^{\circ}C$ in CHC, and over $11^{\circ}C$ in HESPC. On the other hand, as to the strength properties according to W/C, the less W/C was, the more strength development was excellent. If this study is to be used in construction filed on a basis of this result, this researcher is considered as possible of the economic execution of construction by advancing the early strength and by the reduction of construction cost according to shortening construction duration.

• Korean Institute of Interior Design Journal
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• v.13 no.5
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• pp.206-214
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• 2004

본 연구는 사무공간에 영향을 주는 물리적 환경 요소 (공간, 가구배치, 미, 주변요소)를 제시하고 각 환경 요소들과의 관계를 파악하며 각 물리적 환경요소들과 직업 만족도 (급여, 진급, 책무, 상사와의 관계, 물리적 공간과 배치, 수업방법의 향상, 현재 직업 만족도)와의 관계를 분석하는데 연구의 목적이 있다. 또한 물리적 환경 요소들, 직업 만족도와 개인 신상 (나이, 성별, 지위, 교육수준, 교육 경력) 의 특성들과의 상관관계를 알아보고자 한다. 본 연구는 오클라호마 주립대학교의 종신 재직권을 가진 교육대학 교수들을 대상으로 세 가지 가설을 바탕으로 작성된 설문지를 배포하여 조사되었다. 각 교수들의 사무공간은 1997년에 개보수를 마치고 그 해 여름부터 사용하고 있다. 설문은 현재 사용하고 있는 사무공간에 대한 평가, 직업 만족도에 대한 평가와 개인 신상의 특성에 대한 질문으로 조사되었다. 조사 결과 사무공간에 영향을 주는 물리적 환경 요소들 간에 밀접한 관계가 있다는 가설이 입증되었고, 또한 조사 결과 물리적 환경의 만족도가 증가할수록 직업만족도가 증가하는 것으로 물리적 사무환경에 대한 만족도와 직업에 대한 만족도가 직접적인 관계가 있다는 가설 또한 확증되었다. 물리적 환경요소, 직업 만족도와 개인 신상의 특성들과의 상관관계가 있다는 가설은 전체적으로는 입증되지는 않았지만 부분적으로 요소들 간에 관계를 보여주고 있다. 남성이 여성보다 가구배치에 대해 불만족스러웠고 교육경력이 적을수록 사무공간의 냉난방과 환기에 대한 불만족을 보였다. 본 연구의 결과는 교수들의 사무환경의 부정적, 긍정적 견해를 지각하여 사무 환경의 질을 높이는데 도움이 되는데 중요한 역할을 할 수 있겠다. 본 연구는 교육대학의 교수들에 국한되어 있었던 바 추후에는 전체 교육자들을 대상으로 장기간의 관찰을 통한 연구가 요구되어 진다.신만의 고유한 해결책으로 발전시키는지를 고찰하고자 한다. 본 논문의 목적은 서울을 사례분석 중 하나로 사용하여 인테리어 디자인 분야의 경계를 대도시로 확장하는 동시에 새로운 적용영역의 가능성을 탐구하는데 있다 하겠다.[C/N]의 값을 나타내었다.다.다.화 기술, 구동방법등에 대한 기술개요와 국내외 기술동향에 대하여 소개하고자 한다.었다.다._{2}$가 0.25[wt%] 첨가된 시편의 20[.deg.C]에서의 유전상수는 16,700으로 최대값을 유전손실을 1.28[%]로 최소값을 나타내었다. 또한 모든 시편은 온도 및 주파수에 따라 유전상수가 완만하게 변화하는 유전이완 특성을 나타내었다.다.수적인 물의 양에 따른 DIAION WA30의 라세미화 효율에 관하여 실험한 결과, 물의 양이 증가할수록 그 효율은 감소하였다. DIAION WA30을 라세미화 촉매로 사용하여 아이소옥탄 내에서 라세믹 나프록센 2,2,2-트리플로로에틸 씨오에스터의 효소적 DKR 반응을 수행해 보았다. 그 결과 DIAION WA30을 사용하지 않은 경우에 비해 반응 전환율과 생성물의 광학 순도는 급격히 향상되었다. 전통적 광학분할 반응의 최대 50%라는 전환율의 제한이 본 연구에서 찾은 DIAION WA30을 첨가함으로써 성공적으로 극복되었다. 또한 고체 염기촉매인 DIAION WA30의 사용은 라세미화 촉매의 회수 및 재사용이 가능하게 해준다.해준다.다. TN5 세포주를 0.2 L 규모 (1 L spinner flask)oJl에서 세포간의 응집현상 없이 부유배양에 적응,배양시킨 후 세포성장 시기에 따른 발현을 조사한 결과 1 MOI의 감염조건 하에서는 $0.6\times10^6$cell/mL의 early exponential시기의 세포밀도에서 72시간 배양하였을 대 최대 발현양을 나타내었다. 나타내었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.384-390
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• 2018

Air and soil are being contaminated by the environmental pollution as a result of climate change and urbanization, resulting in water pollution reaching serious levels. In this studies, we investigated the use of antimicrobial copper for the removal of biological pollutants from water system. Specifically, we tested its effects against E. coli, B. subtilis, S. aureus, K. pneumoniae and P. aeruginosa. Made a sphere shape having a diameter of 2cm using a strip-shaped copper wire of 0.5g, 1g and 2g. And then, to confirm the antimicrobial activities, each copper ball was equipped in the broth which inoculated each pathogens. The results showed that bacterial growth of the five test bacteria was inhibited by more than 99% after reaction with a 0.5 g copper ball for at least 20 minutes. Based on the these results, if perform the further experiment such cytotoxicity, it is expected that will be enough to be used as a filter for water quality purification. The developed technique is expected to be widely applied in various industries.

• Analytical Science and Technology
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• v.25 no.1
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• pp.39-49
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• 2012

A method to detect 37 volatile organic compounds (VOCs) in surface water was described based on headspace solid-phase micro extraction and gas chromatography-mass spectrometry. VOCs in water were vaporized for 30 min at 40 $^{\circ}C$ in a headspace vial and adsorbed on 85 ${\mu}m$ carboxen-polydimethylsiloxane. Under the established condition, the lowest quantification limit was 4.1-96 ng/L by using 4.0 mL water sample, and the relative standard deviation was less than 15% at concentrations of 0.05 and 0.50 ${\mu}g/L$. The detection limits meet lower concentration than 1/10 of the water quality criteria for VOCs established by the US EPA or Germany. The LOQ is a sensitivity which the monitoring for the establishing water quality criteria requires. When the proposed method was used to analyze the target compounds in sixteen surface water samples and total 16 VOCs were detected in surface water samples collected from Gum-River. Maximum concentrations of VOCs detected were not exceeded the EPA or Germany guidelines in any of the samples.

• Analytical Science and Technology
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• v.26 no.5
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• pp.326-332
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• 2013

Geosmin and 2-methylisoborneol (2-MIB) are volatile organic compounds responsible for the majority of unpleasant taste and odor events in drinking water. Geosmin and 2-MIB are byproducts of blue-green algae (cyanobacteria) with musty and earthy odors. These compounds have odor threshold concentration at ng/L levels. It is needed to develop a sensitive method for determination of geosmin and 2-MIB to control the quality of drinking water. In this study, geosmin and 2-MIB in water samples were determined by gas chromatography-mass spectrometry (GC-MS) with headspace-solid phase microextraction (HS-SMPE). The detection limits of this method were 1.072 ng/L and 1.021 ng/L for geosmin and 2-MIB, respectively. Good accuracy and precision was also obtained by this method. Concentrations of the two compounds were measured in raw waters from Nakdong River in the cyanobacterial blooming season. Water bloom formed by cyanobacteria has been occurred currently in Nakdong River. It is needed to investigate the concentrations of geosmin and 2-MIB to control the quality of drinking water from Nakdong River. Both geosmin and 2-MIB were detected in raw waters from Nakdong River at concentrations ranging from 4 to 24 ng/L and 6 to 16 ng/L, respectively.

• Korean Journal of Environmental Agriculture
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• v.26 no.3
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• pp.223-227
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• 2007

This study was carried out to establish the reasonable level of nitrogen (N) fertilization based on soil nitrate nitrogen $(NO_3-N)$ content for cucumber (Cucumis sativus L.) under plastic film house. Cucumber plants were cultivated with standard and free N fertilization in eight soils which had various amount of $NO_3-N$ ranging from 67 to 343 mg/kg. The yield of cucumber was in the range of 1006 to 2369 g/plant depending on the nitrogen supplying capability of soils. The amount of $NO_3-N$ in the soil was negatively correlated with agronomic efficiency (AE) and N use efficiency (NUE). The critical level of soil $NO_3-N$ content for cucumber in N free fertilization was found to be about 260 mg/kg in Cate-Nelson analysis of variance between soil $NO_3-N$ and AE or NUE. Also the same critical soil $NO_3-N$ content was found in the yield and amount of N uptake of cucumber under N free fertilization. A standard N fertilization was required when soil $NO_3-N$ content was below 70 mg/kg. The optimal application rate of N fertilizer for cucumber in the soils containing $NO_3-N$ between 260-70 mg/kg could be recommended by the equation Y=-1.032X+269.2 (Y: N fertilization rate, kg/ha; X : soil $NO_3-N$ content mg/kg).

• Informatization Policy
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• v.28 no.4
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• pp.76-92
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• 2021

The value of personal information is increasing with the digital transformation of the 4th Industrial Revolution. The purpose of this study is to analyze the efficiency of personal information protection efforts of 2,000 private companies. It uses a stochastic frontier approach (SFA), a parametric estimation method that measures the absolute efficiency of protective activities. In particular, the personal information activity index is used as an output variable for efficiency analysis, with the personal information protection budget and number of personnel utilized as input variables. As a result of the analysis, efficiency is found to range from a minimum of 0.466 to a maximum of 0.949, and overall average efficiency is 0.818 (81.8%). The main causes of inefficiency include non-fulfillment of personal information management measures, lack of system for promoting personal information protection education, and non-fulfillment of obligations related to CCTV. Policy support is needed to implement safety measures and perform personal information encryption, especially customized support for small and medium-sized enterprises.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.7
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• pp.1267-1273
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• 2022

Although the Korea shipbuilding industry has recently been receiving most of the orders for ships in the world, production processes are being disrupted due to a shortage of manpower at the production site. This is because the workers quit the shipyard as both work and wages were reduced due to the long slump in the shipbuilding industry. The main reason for the increase in orders was the large-scale orders for Qatar LNG carriers, and the situation in which the technical specifications required for ships are becoming more complex is also working to an advantage. Because the contract delivery time is of utmost importance for ships, the dock launch plan is the most important management item among the shipyard's major processes. The structure to be built in the dock may be a hull that has left the design work or a finished vessel, and in some cases, it is often at the level of some blocks of the hull. When launching, the hull is affected by the hogging or sagging moment due to the fluid force, and securing the safety of the structural strength of the block connection is of utmost importance. In a normal process, the connecting member launches after welding has been completed, but in actual shipbuilders, quick decision-making is needed on the conditions for securing structural safety to comply with the docking schedule. In this study, a detailed analysis method and applicability using a bending stress evaluation method and finite element analysis modelling were analyzed to rationally judge the above-mentioned problems from an engineering point of view. The main contents mentioned in the thesis can be used as good examples when conducting similar structural strength evaluations in the future.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.2
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• pp.1-14
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• 2023

This study derives quantitative data on how much the fiscal deficit of subway operation agencies can be reduced in the process of charging free rides for the elderly in metropolitan subways during peak periods. In smart card data, every trip of elderly is recorded except fares. Therefore, it is required to establish a methodology for estimating the fares of elderly passengers and distributing them to subway opertation agencies as income. This study builds a simultaneous dynamic traffic allocation model that reflects the assumption that elderly selects a minimum time route based on the departure time. The travel route of the elderly is estimated, and the distance-proportional fare charged to the elderly is calculated based on this, and the fare is distributed by reflecting the connected railway revenue allocation principle of the metropolitan subway operating agencies. As a result of conducting a case study for before and after COVID-19 in 2019 and 2020, it is analyzed that Seoul Metro's annual free loss of 360 billion won could be reduced 6~8% at the morning peak (07:00-08:59), and 13~16% at the morning and afternoon peak (18:00-19:59).

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.5
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• pp.437-445
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• 2018

Devices have a lot of small breakdowns rather than big breakdowns. But it often wastes time and increases cost of maintenance, such as calling a service technician for small breakdowns. So, if we use remote control and monitoring service using Internet of Things, we can minimize the time period and cost for the maintenance. However, security is important because remote control and monitoring services contain personal information which when leaked, may be dangerous. There are many types of Internet based monitoring devices that are in use, but it is difficult to expect a high level of security because there are many cases in which the performance is minimal. Therefore, in this paper, we classify remote control and monitoring services based on Internet of Things type and derive encryption requirement for four types. We also compared and analyzed the lightweight cryptographic algorithms that can be expected to use high performance even on the Internet of Things. And it is derived that LED is used as a equipment management type, DESLX as a environment management type, CLEFIA as a healthcare management type and LEA as a security management type are the optimal lightweight cryptographic algorithms for each type.