• Journal of The Korean Astronomical Society
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• v.33 no.2
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• pp.89-95
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• 2000

As an efficient method to detect blending of general gravitational microlensing events, it is proposed to measure the shift of source star image centroid caused by microlensing. The conventional method to detect blending by this method is measuring the difference between the positions of the source star image point spread function measured on the images taken before and during the event (the PSF centroid shift, ${\delta}{\theta}$c,PSF). In this paper, we investigate the difference between the centroid positions measured on the reference and the subtracted images obtained by using the difference image analysis method (DIA centroid shift, ${\delta}{\theta}$c.DIA), and evaluate its relative usefulness in detecting blending over the conventional method based on ${\delta}{\theta}$c,PSF measurements. From this investigation, we find that the DIA centroid shift of an event is always larger than the PSF centroid shift. We also find that while ${\delta}{\theta}$c,PSF becomes smaller as the event amplification decreases, ${\delta}{\theta}$c.DIA remains constant regardless of the amplification. In addition, while ${\delta}{\theta}$c,DIA linearly increases with the increasing value of the blended light fraction, ${\delta}{\theta}$c,PSF peaks at a certain value of the blended light fraction and then eventually decreases as the fraction further increases. Therefore, measurements of ${\delta}{\theta}$c,DIA instead of ${\delta}{\theta}$c,PSF will be an even more efficient method to detect the blending effect of especially of highly blended events, for which the uncertainties in the determined time scales are high, as well as of low amplification events, for which the current method is highly inefficient.

• Journal of Korea Port Economic Association
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• v.32 no.2
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• pp.91-103
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• 2016

The purpose of this study is to analyze the efficiency and productivity of domestic trucking transportation companies using DEA-CCR, BCC, and Malmquist indexes. Here, we analyze the top 14 domestic trucking transportation companies, based on cargo volume. The number of freight agents, trucks, and assets are used as input variables, and cargo volumes and sales are used as output variables. The efficiency of trucking transportation companies is examined using a DEA approach, and Malmquist indexes are applied to analyze productivity. According to the DEA results, the efficiency levels of the CCR, BCC, and scales for three companies (DMU 4, 5, and 10) are 1, indicating that these companies are operated efficiently. At the same time, the Malmquist indexes show that all companies have values smaller than 1, except for the period 2012-2013, indicating that their productivity decreased. Furthermore, the TECI indexes were all larger than 1, except for the period 2012-2013, indicating that the companies are efficient. Lastly, all TCI indexes are smaller than 1, except for the period 2012-2013, indicating regressing trends.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.1
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• pp.77-86
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• 1997

The advanced development in many fields of engineering and science has caused much interests and demands for crashworthiness and non-linear dynamic transient analysis of structure response. Crash and impact problems have a dominant characteristic of large deformation with material plasticity for short time scales. The structural material shows strain rate-dependent behaviors in those cases. Conventional rate-independent constitutive equations used in the general purposed finite analysis programs are inadequate for dynamic finite strain problems. In this paper, a rate-dependent constitutive equation for elastic-plastic material is developed. The plastic stretch rate is modeled based on slip model with dislocation velocity and its density so that there is neither yielding condition, nor loading conditions. Non-linear hardening rule is also introduced for finite strain. Material constants of present constitutive equation are determined by experimental data of mild steel, and the constitutive equation is applied to uniaxile tension loading.

• Korean Journal of Health Education and Promotion
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• v.31 no.5
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• pp.147-158
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• 2014

Objectives: This study aims to examine the association of depression, suicidal behaviors with smartphone use behaviors among Korean adolescents. Methods: We analyzed data from 'Youth Health and Life Skills Survey' in 2013. The survey was based on self-reported questionnaires distributed to 915 grade 7th and 8th students at four middle schools in Gangdong-gu, Seoul, Korea in 2013 to evaluate the effects of 'Youth Health and Life Skills' program. Depression and suicidal behaviors were measured in terms of the experience rate, and smartphone use behaviors were measured with average hours of smartphone use a day and overindulged behaviors in smartphone use by using 5-point Likert scales. We examined the association of depression and suicidal behaviors with smartphone use behaviors by using t-test and regression analyses. Results: 21.5% of respondents have ever felt depressed or hopeless to lose interest in school life almost everyday for 2 weeks or longer in the past year. The experience rate of suicidal ideation, suicide plan, and suicidal attempt were 21.1%, 6.1%, and 5.7%, respectively. The mean of average hours of smartphone use a day was 3.9 hours, and the mean score of overindulged behaviors in smartphone use was 2.99. The students who have experienced depression and suicidal behaviors were more likely to have more smartphone using time and higher scores of overindulged behaviors in smartphne use than those who have not. Conclusion: We concluded that for preventing addictive or problematic smartphone use behaviors among adolescents we should consider and develop more positive strategies for the moderate use of smartphone than regulatory measures, which include the implementation of skill-based health education program including life skills at schools and the development of smartphone applications useful for resolving mental stress and promoting mental health.

• Journal of Biomedical Engineering Research
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• v.18 no.3
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• pp.307-313
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• 1997

he photoconductive gain mechanism in amorphus silicon devices was investigated in connection with applications to radiation detection. Various device types such as p-i-n, n-i-n and i-i-p-i-n structures were fabricated and tested. Photoconductive gain was measured in two time scales : one for short pulses of visible light(<$1{\mu}sec$) which simulate the transit of energetic charged particles or ${\gamma}$-rays, and the other for rather long pulses of light(1msec) which simulate x-ray exposure in medical imaging, We used two definitions of phtoconductive gain : current gain and charge gain which is an integration of the current gain. We obtained typical charge gains of 3~9 for short pulses and a few hundreds for long pulses at a dark current density level of 10mA/$cm^2$. Various gain results are discussed in terms of the device structure, applied bias and dark current density.

• Journal of The Korea Institute of Healthcare Architecture
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• v.22 no.1
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• pp.39-49
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• 2016

Purpose: This is the ex-post evaluation on "the Central General Hospital in Quang Nam Province in Vietnam" funded by Korean ODA. Through this evaluation, this study tries to explore useful ways to improve the effectiveness of Korean ODA projects related to hospital establishment. Methods: Field survey and analysis of questionaire to the staffs and patients of Quang Nam Province General Hospital were conducted twice in 2012 and 2014 after the completion of the Hospital. Two sets of surveys and questionaire outcomes have been comparatively analysed by statistics in order to seek the trend of satisfaction level of hospital users and find out the improvement way in hospital design and construction. Results: The satisfaction level on the hospital was relatively high and that of 2014 is higher than that of 2012. The satisfaction level of the users was recorded in Likert 5 scales. Continuous facility complement and maintenance is considered as the main contributor in increasing the satisfaction level of users. As far as the satisfaction level of outpatient is concerned, that of 2012 was recorded as 3.65 and that of 2014 was 4.05. In case of inpatient, the satisfaction level on the hospital in 2012 was 3.76, and 4.06 in 2014. Implications: In overseas hospital projects, proper hospital project management system including medical service plan, strategic plan, brief, design & construction and maintenance have to be put together effectively and efficiently for the success of the hospital project. At the same time local climate, culture, building material and local code have to be considered in order to build sustainable hospital.

• The KIPS Transactions:PartD
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• v.8D no.6
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• pp.761-770
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• 2001

As software industry is rapidly evolving, IT business enterprises have been meeting with cutthroat competition in developing software. As software reusability, time to market, and maintainability are considered as a competitive edge, software component techniques have lately attracted considerable attention. Currently, although there are some supporting tools for developing software components, they do not have tight connections among component developing processes such as component identification, component modeling, detailed design, code generation, deployment, and testing. And it is restrictive for users to construct various scales of components on component platform architecture. In this paper, we provide an implementation and a design of a supporting tool for constructing platform-independent software components, which covers all development lifecycles of components. In the phase of component modeling, platform independent, conceptual components are identified from domain model information in the view of system partitioning. Detailed design and implementation of a component are performed on the J2EE platform architecture. And the changes on the design model and source codes are consistently managed by using round-trip techniques.

• The Korean Journal of Pain
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• v.6 no.1
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• pp.49-54
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• 1993

The use of intravenous patient-controlled analgesia is an effective and increasingly used means of providing postoperative pain relief. Recently a non-electric, disposable and portable infusor, the Baxter $Infusor^{(R)}$, has developed. This delivers not only a continuous drug infusion but can also deliver extradoses of medication on demand. The present study examined the benefits of two kinds of analgesics for pain management in 28 patients undergoing gynecological surgery. One group, 14 patients, received i.v. meperidine 0.5 mg/kg as loading dose in the recovery room and PCA with meperidine 3 mg/kg/day for 3 days only(M group). In the other group, 14 patients, also received i.v. meperidine 0.5 mg/kg as loading dose in the recovery room and PCA meperidine 3 mg/kg/day for 3 days and droperidol 5 mg(MD group). The PCA device used was the Baxter $Infusor^{(R)}$. This unit was fitted with patient control module which had a flow rate 0.5 ml/hr and the lockout time was 15 min. Resulting from the study, the MD patients in the first and second days post-operatively, reported less pain compared with the M group. VAPS(Visual Analogue Pain Scales) values were $3.52{\pm}l.61$ vs. $2.22{\pm}0.69$, $2.38{\pm}1.12$ vs. $1.45{\pm}0.48$ and $1.93{\pm}1.65$ vs. $0.98{\pm}0.36$, respectively pertaining to M and MD groups. In conclusion, the MD group with meperidine and droperidol(mixed regimen) provided more effective postoperative analgesia than M group(meperidine only).

• Applied Microscopy
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• v.36 no.1
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• pp.25-33
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• 2006

This study applied a bleaching agent. which is commonly used in the beauty salons, to the hair of normal adult women, collected the hair immediately and 10 days and 20 days from the bleaching, were investigated the degree of degradation of the hair by using scanning and transmission electron microscopes. The surface of hair just after bleaching was observed to be similar to that of normal hair, showing no split or damage of scale. In the hair of 10 days after bleaching, however, the scale came off. From this time, scale on the cuticular layer of hair began to be separated. In 10 days from bleaching, the scale on the cuticular layer was separated from hair and some cytoplasm of cuticular cells was broken into pieces or fell off. The cell remains made the surface coarse and uneven. At this period, damaged scales had a sharp end. In the hair of 20 days after bleaching, scale fell off from the whole surface of the hair and the surface looked rough. On the bleached hair, many vacuoles were formed in the endocuticle of cuticular cells. As a result, deformation caused by the formation of vacuoles in cuticles broke up the cuticular cells.

• Korean Institute of Interior Design Journal
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• v.21 no.5
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• pp.145-152
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• 2012

Since 1966 when James Turrell completed his studies on Art, he has been working on the consistent theme of Art. For the 46 years of time, site contexts, scales, methods of light have been changed and they made Turrell's unique 'project series'. Each series has different spatial, visual-perceptual forms and characteristics from other series. The differences were caused by the given situations, but also Turrell intentionally pursued it. However, there are essential theme of art that has not changed in most of Turrell's projects. Target of this paper is to study the unchanged theme as well as the differences. The study starts with three questions: first, what is the geometrical space composition?, second, what is the visual-perceptual phenomenon?, third, what is the hidden consistent theme? This research focuses on three case projects: Wedgework, Space Division Constructions, Skyspaces. These project series are in between the early small object-like installations and the late mega-scale outdoor projects. The study found that geometrical space composition has important role to give visual-perceptual dynamism to the viewer. The phenomenological perception is connected to the questions of relationship between human and space, ultimately human and the world. Although the Merleau-Ponty's philosophy has been related to the work of Turrell in various previous studies, Cartesian 3-dimensional geometry has also crucial role to experiment a viewer's perceptual boundaries. Image of infinity is another aspect of three cases, especially Space Division Constructions and Skyspaces. Through these structure, Turrell's work lead to an ultimate question of meaning for human existence in infinite space. It is hoped that this paper is helpful for Architecture and Interior design field in which light and space are essential.