• 대한치과교정학회지
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• 제5권1호
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• pp.25-31
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• 1975

A study of the effects of multibanded orthodontic appliances on the oral lactobacilli was conducted on 41 multibanded group and 41 caries free group. The following conclusions were obtained. 1. In multibanded group, the average count of lactobacilli per milli-liter of saliva showed about 219,300 in male and 254,100 in female. In caries free group, the mean count of lactobacilli per milli-liter of saliva showed about 66,700 in male and 68,500 in female, Therefore, the average of lactobacilli in multibanded group was much higher than that of the caries free group in both sexes. 2. The average of all the types of lactobacilli colonies (Disk-type, Bell-type, Y-type) in multibanded group was much more than that of caries free group. 3. Multibanded orthodontic appliances were found to sufficiently alter oral environment to significantly affect disk-types and total counts in both sexes and bell-type in female, at $1\%$ level of confidence. But changes in bell-type and y-type, in male, were considered to be significant at $5\%$ level of confidence.

• 한국항만경제학회지
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• 제22권1호
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• pp.17-38
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• 2006

This paper suggests the development device of Busan-Jinhae free Economic Zone(BJFEZ) to strengthen the competitiveness of the Port of Busan and promote the regional development in Busan. It deals with the securable feasibility of necessary sites and development costs and financial resources, the foreign investments figure, and the structure of the BJFEZ Authority. In addition, to evaluate the background, process, and contents of 'Special Purpose Local Government', the paper looks into the amendment proposal of 'Act on designation and management of free economic zones' suggested by the central government from the regional view of point. As proposals to promote and activate BJFEZ, it is recommended in the paper that it is required, first, to draw the detailed political methods to guarantee sound and sustainable development project and investment environment in accordance with regional characteristics prior to marketing, second, to develop and implement differentiated policy means to facilitate foreign investment, third, to strengthen specialty of the BJFEZ authority, and finally, to set up the supporting role and cooperation of both the central and local governments.

• ETRI Journal
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• 제43권4호
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• pp.580-593
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• 2021

When operating in confined spaces or near obstacles, collision-free path planning is an essential requirement for autonomous exploration in unknown environments. This study presents an autonomous exploration technique using a carefully designed collision-free local planner. Using LiDAR range measurements, a local end-point selection method is designed, and the path is generated from the current position to the selected end-point. The generated path showed the consistent collision-free path in real-time by adopting the Euclidean signed distance field-based grid-search method. The results consistently demonstrated the safety and reliability of the proposed path-planning method. Real-world experiments are conducted in three different mines, demonstrating successful autonomous exploration flights in environment with various structural conditions. The results showed the high capability of the proposed flight autonomy framework for lightweight aerial robot systems. In addition, our drone performed an autonomous mission in the tunnel circuit competition (Phase 1) of the DARPA Subterranean Challenge.

• Bulletin of the Korean Chemical Society
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• 제14권2호
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• pp.220-225
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• 1993

The influence of temperature and pressure on the free energy of the ion hydration has been considered. The ion radii measured by conductometric method and the saturated dielectric constant cited from other works were used to calculate the free energy in the hydration shell. The Born equation was modified in order to fit in our model. In our model, the environment of ion consists of three regions. The innermost one is the hydration shell in which water is immobilized and electrostricted, the middle one is the one which contains less ordered waters than the bulk medium, and the outermost one is the bulk water which is under the influence of the electric field of ion. Our results for the free energy of ion hydration were compared with those of other attempts. Especially, ${\Delta}$G$_{hyd}$ of $Li^+$ ion is considerably too negative in this study at given temperature, comparing with those of other attempts. But ${\Delta}$G$_{hyd}$ of other ions coincides with each other.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제12권3호
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• pp.35-41
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• 2006

At the moment, a lot of interest in the research on Gnotobiotic Pigs are increasing in order to produce alternative human organs. So, it is very important to design and build proper housing facilities for Germ Free Pigs. Among the design issues related to Gnotobiotic Pigs' farms, circulation system takes a high position because it carries an important role in keeping the pig's housing environment aseptic. Considering those, this study aims to propose the guidelines for the design of circulation system in Germ Free Pig's facilities. The results of this study are as follows. At first, functional areas of Germ Free Pigs' facilities have been divided into three categories according to the clean level; aseptic area, semi-aseptic area, and non-aseptic area. Secondly, the basic principles of circulation system have been proposed. Finally, circulation system of Gnotobiotic Pigs' facility has been explored as a form of diagram according to the circulating subjects. These include human circulation, pig's circulation, and goods' circulation. This study has some limitations in that it is transcendent and lacks empirical evidence. Despite of some weaknesses, it is expected to give some useful guidelines for the design of circulation system in Germ Free Pigs' facilities.

• 무역상무연구
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• 제16권
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• pp.117-154
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• 2001

The objective of the study is to propose to the strategy to make korean main ports to international logistics center in Northeast Asia. so this study's construction is constructed four steps. First, analysis the environment of economy, business and logistics industry in Northeast Asia. Second, analysis the constructions and characters of Free Zone Act. Third, analysis of Korean Government's policy about Free Zone. Forth, propose the growing strategy of Free Zone. In 1999 Northeast Asia was adopted in Korea, which will facilitate the process and strengthen the international logistics capability as a international logistics hub in Northeast Asia. But only adoption in the point of law is not enough to growing korean main seaport and airport to a international logistics hub. so various strategies are needed. In this study, we propose the growing strategies that are to establish and manage the free zone of ports and its hinterland are: the establishment of a long-term vision of international logistics complexes, the improvement of the proximity to markets/customers by way of linkage of global networks, the activation of the industrial complex in hinterland, the development of the skilled labor and the labor climate, the cooperation between governmental bodies and government/provincial bodies, continuous development of logistics infrastructure and so on.

• 한국주거학회논문집
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• 제11권4호
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• pp.35-42
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• 2000

The purpose of this study is to prepare desirable elderly housing facilities system in compliance with various characteristics of each region and to help establish policies regarding elderly housing facilities. Present realities and problems of the eight free welfare facilities of two sorts, a free home for the aged and free nursing home in Jeju Province have been studied. In Jeju Province, the average life span and the ratio of the aged people older than 65 are longer and higher than other provinces and the mentality of self-reliance is more widespread. The results are as follows : 1) The average age of the aged is 70 or older and more facilities are located in rural districts. 2) Some facilities are located in the places where are not adequate for life of the aged, and not even suitable as welfare facilities for the aged. 3) Housing environmental conditions of the facilities are relatively good, while indoor facilities for recreation and social life were not well equipped. 4) Life in the facilities can be assessed relatively free, while individual privacy is not well protected. 5) Major community contacting activities included home help service, participation in regional activities, opening facilities to the community.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.90-96
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• 2014

The conventional SnPb solders were widely used for several decades in the electronic packing system due to the superior mechanical properties such as low melting point, better wettavility and good mechanical fatigue. However, in recent years, owing to adverse effect on the human health and environment, conventional SnPb solders have been replaced by Lead-free solders. In this research, the shear punch(SP) test of Sn-4Ag-(Cu)/Ni pad was performed. Pb-free solder alloys which are the environmentally friendly of the electronic components were performed at $150^{\circ}C$ for 100hr~1000hr to artificial aging processing. In order to evaluate the mechanical properties of solder joints, the SP test was conducted at $30^{\circ}C$ and $50^{\circ}C$. As a result, the maximum shear strength of almost the whole specimens was decreased with the increase in aging time and temperature of SP test. The mechanical properties of Sn-4Ag-0.5Cu solder were most excellent in all Pb-free solder which were produced by the SP test at $30^{\circ}C$.

• 한국생산제조학회지
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• 제20권2호
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• pp.187-192
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• 2011

UBM(Under Bump Metallurgy) is very important for successful realization of Flip-Chip technology. In this study, it is investigated the interfacial reactions between various Sn-Ag solder alloys and Ni-P/Au UBM and Cu plate finish. It is also evaluated the shear strength by using the micro shear-punch test method for Sn-37Pb alloy, binary and ternary alloys of environment-friendly Pb-free solder alloys which are applied in the electronic packages. In terms of interfacial microstructure, the Pb-free solder joints have thicker IMCs than the Sn-Pb solder joints. The thickness of IMC is related to Reflow time. The IMC has been observed to grow with the increase in Reflow time. As a result of the shear test, in case of Max. shear strength, Pb-free solder showed the highest strength value and Sn-37Pb showed the lowest strength value 10 be generally condition of Reflow time.

• Bulletin of the Korean Chemical Society
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• 제29권2호
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• pp.363-371
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• 2008

As a computational method for the discovery of the effective agonists for PPARd, we address the usefulness of molecular dynamics free energy (MDFE) simulation with explicit solvent in terms of the accuracy and the computing cost. For this purpose, we establish an efficient computational protocol of thermodynamic integration (TI) that is superior to free energy perturbation (FEP) method in parallel computing environment. Using this protocol, the relative binding affinities of GW501516 and its derivatives for PPARd are calculated. The accuracy of our protocol was evaluated in two steps. First, we devise a thermodynamic cycle to calculate the absolute and relative hydration free energies of test molecules. This allows a self-consistent check for the accuracy of the calculation protocol. Second, the calculated relative binding affinities of the selected ligands are compared with experimental IC50 values. The average deviation of the calculated binding free energies from the experimental results amounts at the most to 1 kcal/mol. The computational efficiency of current protocol is also assessed by comparing its execution times with those of the sequential version of the TI protocol. The results show that the calculation can be accelerated by 4 times when compared to the sequential run. Based on the calculations with the parallel computational protocol, a new potential agonist of GW501516 derivative is proposed.