• 한국지진공학회논문집
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• 제7권2호
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• pp.39-48
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• 2003

반응수정계수의 핵심구성요소인 연성계수에 대하여 통계적 분석을 수행하였다. 연성계수의 체계적인 산정을 위하여 총 1,860개의 지진기록을 수집하였다. 수집된 지진기록을 지반 전단파의 평균속도에 따라 4가지로 분류하고, 탄소성 이력거동을 가지는 단자유도 구조물에 대하여 비탄성 스펙트럼을 작성하였다. 작성된 비탄성 스펙트럼으로부터 연성계수를 구하고, 변위연성비, 토질조건, 규모 및 진앙거리가 연성계수에 미지는 영향을 분석하였다. 토질 조건별로 평균연성계수를 구하고, 산정된 연성계수의 산포도를 검토하기 위하여 변동계수를 산정하였다.

• Bulletin of the Korean Chemical Society
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• 제24권1호
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• pp.70-74
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• 2003

The heterogeneous bioluminescence immunoassay for digoxin was developed using photoprotein, native aequorin as a label and the site-directed immobilization technique based on avidin/biotin interaction. Aequorin is a bioluminescence protein, originally isolated from the jellyfish Aequoria Victoria and an attractive label in analytical applications because of sensitive detection due to virtually no background bioluminescent signal. Digoxin is a cardioactive drug, and its therapeutic level in serum is at low concentration with very narrow therapeutic index. The aequorin-digoxigenin conjugates were synthesized by the N-hydroxysuccinimide ester method and characterized in terms of bioluminescent residual activity. The resulting dose-response curve shows that the detection limit is $1.0\;{\times}\;10^{-10}\;M$ and a dynamic range is three orders of magnitude, which was obtained by $1.0\;{times}\;10^{-10}\;M$ conjugate and 0.9 μg/mL anti-digoxin antibody. Three structurally similar molecules to digoxin were examined for their cross-reactivity. None of these three compounds showed any crossreactivity with digoxin antibody employed in this study. Standard amounts of digoxin corresponding to the therapeutic range were spiked into the each serum solution. Study of the serum matrix effect indicated that correlation coefficient shows good agreement between luminescence light intensity between in buffer and in serum.

• 한국소음진동공학회논문집
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• 제17권5호
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• pp.373-378
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• 2007

Today, the use of the sound absorptive material is increasing to improve the room acoustics in the auditorium and music hall, etc. Usually, the sound absorption materials have been used to enhance the performance of a noise barrier and improve the room acoustics in construction site. Generally, the sound absorbtion coefficients are the most important factor reflecting the sound absorbtion performance. There are two methods to measure the sound absorption coefficient. The first one is the reverberation room method, and the second is the impedance tube method. In this study, we measure the sound absorbtion coefficients using these two methods, and then we compared the results of the sound absorbtion coefficients to look into the difference of results between reverberation room method and impedance tube method. Also we compared the results of the sound absorbtion coefficients with respect to the size of sample and the volume of reverberation room. From the experiment, we could see that the sound absorbtion coefficients are measured equally for different sample size. But the sound absorbtion coefficients are measured differently according to test methods and test conditions.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.130-135
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• 2000

The purpose of this study is to examine the physical properties of water-permeable concretes. The water-permeable concrete with cement-aggregate ratios of 1:3.5 to 1:6.0 and two type of coarse aggregate size of 8~13 and 13~18mm used OPC(ordinary portland cement) as a binder and superplasticizer are prepared, and then tested for flexural strength, compressive strength, compressive strength, continuous void percentage and coefficient of water permeability. It is concluded from the test result that the superior flexural and compressive strengths, coefficient of water permeability and continuous void percentage of water-permeable concretes that use OPC were obtained at cement-aggregate ratios of 1:3.2, 1:6.0 respectively, The water-permeable concretes with coarse aggregate of 8~13 and 13~18mm size used OPC as a binder havinga flexural strength of 24.81~45.56kgf/$\textrm{cm}^2$, 21.99~40.62kgf/$\textrm{cm}^2$, a compressive stength of 93.63~ 242kgf/$\textrm{cm}^2$, 114.8~191.7.kgf/$\textrm{cm}^2$, a coefficient of permeability of 0.59~1.85kgf/$\textrm{cm}^2$, 0.73~ 2.25kgf/$\textrm{cm}^2$, and a continuos void percentage of 16.6~26.32%, 13.52~24.35% respectively during 28 curing days.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1998년도 지반조사위원회 봄 학술세미나
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• pp.37-46
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• 1998

Several researchers have developed a number of theoretical time factors to determine the coefficient of consolidation by biezocone excess pore water dissipation test in soft clay deposits. However, depending on the assumptions and analytical techniques, the estimated coefficient of consolidation could be in a considerably wide range even for a specific degree of consolidation. These solutions are obtained from an initial excess porewater pressure distribution which can be determined from. either the cavity expansion theory or the strain path method. The 야ssipation of the initial excess porelvater pressure has been usally simulated by means of linear-uncoupled consolidation analysis and then the dissipation curve is normalized by the initial excess porewater pressure for easy use. However. since there is no guidelines or rules on which method gives the best solution for obtaining the coefficient of consolidation from the dissipation curve, the final selection was only based on engineer's extrience and Judgements. Thus, such an arbitrary selection might be inappropriate for a specific site to characterize the consolidation behavior. In this paper, we reviewed various theoretical time factors and, based on this consideration, we mentioned needs for researches in selecting a specific solution that is compatible for Korean clays. Also we listed some source of errors that can be encountered in the procedure of dissipation analysis.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권1호
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• pp.119-131
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• 2014

The phenomenon of cavitation is an unsteady flow, which is nearly inevitable in pump. It would degrade the pump performance, produce vibration and noise and even damage the pump. Hence, to improve accuracy of the numerical prediction of the pump cavitation performance is much desirable. In the present work, a homogenous model, the Zwart-Gerber-Belamri cavitation model, is considered to investigate the influence of the empirical coefficients on predicting the pump cavitation performance, concerning a centrifugal pump. Three coefficients are analyzed, namely the nucleation site radius, evaporation and condensation coefficients. Also, the experiments are carried out to validate the numerical simulations. The results indicate that, to get a precise prediction, the approaches of declining the initial bubble radius, the condensation coefficient or increasing the evaporation coefficient are all feasible, especially for declining the condensation coefficient, which is the most effective way.

• 대한건축학회논문집:구조계
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• 제35권5호
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• pp.161-168
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• 2019

Construction industry is becoming more advanced, but safety accidents are not decreasing and unsafe act (UA) and human errors (HE) are the main causes of safety accidents. Therefore, this study aims to analyze the relationships between unsafe acts and human errors for construction accident prevents. Specifically, the Correlation Analysis is used to quantify 24 combinations of the relationship between the UA and HE. Then, the Kano Model, and Timko Satisfied Coefficient was utilized to find 6 combinations for construction accident prevention plans. As the result of Timko Satisfied Coefficient, an interview was conducted with three safety managers and 6 safety prevention plan is proposed. Through these results, it is expected that the combination of 24 accidents will be basic data of safety management. Especially, the proposed safety prevention plans considering the characteristics of 6 combinations with high correlation can contribute to prevention of safety accidents at the construction site.

• 한국안전학회지
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• 제38권4호
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• pp.60-67
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• 2023

Various lifting slings are used in domestic industrial sites depending on the purpose, form, and environment. Each sling has its characteristics, and safe lifting work is possible when its performance meets the regulations. Therefore, this study analyzed domestic and foreign regulations and guidelines related to chain slings. It identified significant problems by analyzing the chain-sling-related disaster cases. The current status of chain slings used by various industries and the ways to improve chain sling safety were studied. The major chain sling issues were: 1) employing improper components to chains, 2) having different safety coefficients between the regulation and industrial standards, and 3) using chains unsuitable for lifting purposes. Based on these issues, the following measures were proposed to improve chain sling work safety: 1) revise the safety coefficient requirements under the Regulations on Occupational Safety and Health Standards, 2) disseminate specialized sling courses, and 3) strengthen on-site chain slings-related training. In the future, this study is expected to minimize chain use mistakes by unifying the safety coefficient related to chain slings and recognizing the importance of correctly selecting components employed in the chain.

• 한국물환경학회지
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• 제25권2호
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• pp.295-305
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• 2009

The purpose of this study was to understand of water quality characteristics of lake Paldang, especially at a certain representative site, right in front of Paldang dam ($P_2$ site) and to propose the directions of water quality management of lake Paldang. Water characteristics at $P_2$ site was investigated by principle components analysis and the Pearson correlation coefficient analysis. Also, seasonality was identified by the Kruskal-Wallis test and long term trend of nutrients and chlorophyll-a was analyzed by seasonal decomposition method at lake Paldang statistically. The primary factor affecting on water quality at $P_2$ site was identified as nutrients, while physical parameters, such as rainfall and inflow rate were also important factors. At the result of linear regression analysis particulate organic phosphorus (POP) vs total phosphorus (TP) showed very high correlation of 0.78. TP loading was increased annually from 1995 to 2006. Chlorophyll-a and nutrients show seasonality at $P_2$ site. Long term trend of Chlorophyll-a was increased by increase of TP at lake Paldang.

• 한국산업보건학회지
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• 제23권3호
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• pp.243-249
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• 2013

Objectives: This study assessed the status of domestic industrial hygiene laboratories using data from on-site investigation for revision of quality control systems in 2012-2013. Methods: The target laboratories were 60 industrial hygiene laboratories chosen by random selection and nationwide distribution which had participated in on-site investigations for revision of quality control systems from March 2012 to August 2013. The investigation was performed on-site following standard quality control procedures. The score between each group was compared using Mann-Whitney and Kruskal-Wallis tests, and the correlation between analytical career, sex, academic major of analyst and score of analytical performance was expressed as Spearman's rank correlation coefficient. Results: The assessment revealed that the items to be improved, in sequence, were effort at staff training (score 65.5), ability to calculate data (score 73.4), establishment of internal quality control guidelines (score 75.7), laboratory facilities (score 77.1), degree of understanding and skill at gas chromatography (score 77.1). Analysis performance showed a positive correlation with career of analyst (r=0.56, p<0.01). Conclusions: The practice of on-site investigation for quality control systems showed the current status of industrial hygiene laboratories in the first trial. There were many laboratories which needed improvement and development of analytical systems. This assessment can provide information for the systematic operation and improvement of facilities at each laboratory. Further practice of this investigation will lead to a proficiency testing and accreditation system for autonomous quality control as is the practice in many countries, rather than mandatory practice by legal regulation.