• Korean Journal of Construction Engineering and Management
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• v.7 no.5
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• pp.85-93
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• 2006

This study is started from a situation of korean construction which has been undergoing diversity. And risk of construction project has been increased recently. The purpose of this study is to propose the model which is able to estimate the proper manpower by eliciting the variable which is offered in the pre-design and construction phase. The existing method of estimate has a problem with calculating exact costs. For this model, it was analyzed the existing manpower estimating model and used historical data of 38 apartment houses, constructed from 2000 to now. Based on these, the regression model of the construction manpower was built. And then the regression model was verified. The result of verification was relatively adequate in the statistics exept for some cases. This regression model will help make it possible for constructor to estimate the deduction of retirement more accurate than existing method.

• Journal of Digital Convergence
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• v.13 no.9
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• pp.89-98
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• 2015

To celebrate the convergence era, Park Geun-Hye government has adhered to the principle sets out to secure revenue no tax increase due to the underground economy legalization, etc. Recently due to the tax deduction policies such as cash receipts and credit card is like getting better transparency on income. However, focusing on the self-employed Evaded income scale is increasing steadily. For the underground economy legalization, it has the plan to increase the transparency of the capital market due to the strengthening of the cash receipt system and the mobile payment market. The purpose of this study is that it hopes the domestic mobile payment market is expanding for the underground economy legalization. To this end, domestic financial companies are hoping to develop a variety of additional services. And the mobile payments market is hoping to gain the trust our customers due to safety and security, etc. As a result the underground economy is expected to disappear naturally.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.1
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• pp.215-224
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• 1998

The following conclusions were obtained from the non-reconstructed and reconstructed subtraction images of the standard intraoral radiographs which were taken with paralleling technique with Rinn XCP only and with occlusal bite registration for geometric standardization using bilateral mandibular premolar and molar regions of two dry human skulls. 1. The SD of the overall subtraction images of the premolars and molars of the non-reconstructed, that is, the manual superimposition showed statistically significant difference between the non-registered and registered groups. 2. In non-reconstructed and non-registered cases, the quality of the subtraction images were improved when superimposition was focally done and this was more evident in areas where the radiographic images tend to be distorted due to anatomic reasons. 3. In non-reconstructed and registered cases, the subtraction images were consistent regardless of the anatomic site or the focus of superimposition. This means that the geometric standardization with only occlusal bite registration could produce serial radiographs which is suitable for subtraction. 4. The SD of the overall subtraction images of the premolars and molars of the reconstructed, that is, the automatic superimposition showed statistically insignificant difference between the non-registered and registered groups. This means that using reconstruction, subtraction radiography is possible without occlusal bite registration. 5. In reconstructed and non-registered cases, compatible quality of the subtraction images were obtained regardless of the anatomic site or area of the corresponding points. 6. In reconstructed and registered cases, best subtraction images whose quality showed sensitivity to the areas of corresponding points were obtained.

• Journal of Digital Convergence
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• v.14 no.7
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• pp.243-250
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• 2016

The purpose of this study is to prevent school safety accidents by conducting an analytic investigation on safety accidents that occur in elementary, middle and high school during 2010-2014 in Chung-Nam. We used the status of safety accidents in school based on the Chung-nam School Safety and Insurance Association database. Data was analyzed by descriptive Statistics. It was found that the incidence of safety accidents in school has increased, and in the case of elementary schools it was higher than in middle school or high school. Safety accidents occurred most during break time, and in schoolyard, and due to student's carelessness. Safety is one of the most basic human needs. To decrease the incidence of safety accidents, we need to set up with comprehensive safety system including human, physical and environmental factors. Based on the this study, it needs more wide study on various countermeasures and to determine effects.

• Journal of Fisheries and Marine Sciences Education
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• v.5 no.2
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• pp.98-109
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• 1993

By the Article 28 of the Korean Fishing Vessels Act and the Article 47-1 of the Enforcement Ordinance of the Act, fishing vessels over 5 gross tone must be insured the fishing vessels mutual insurance or marine insurance. Therefore the distant-water fishing vessels and vessels registered with Classification Society can be insured to the marine insurance, and non-registered vessels and the small fishing vessels can be insured to the fishing vessels mutual insurance of Fisheries Co-operatives. Moreover, the shipowners of fishing vessels over 5 gross tons to be insured a liability insurance for their crew, and it is to compensate effectively the crewman's accidents prescribed in the Seaman's Act. The shipowner's Liability Insurance to be insured the seaman's Compensation Insurance or the seaman's mutual insurance of the Fisheries Co-operatives and the Protection and Indemnity but they still involve lots of problems to cover the crewman's accidents reasonably. The author's views on the improvement way of the fisheries mutual insurance system are as follows. 1. The size of fishing vessels over 5 gross tons prescribed by the Article 28 of the Fishing Vessels Act must be revised into over 1 gross tons. And the regulations concerning penalties against nonfulfilment of the regulation must be strengthened in order to have legal effectiveness. 2. The level of the government subsidy for the fisheries mutual insurance must be raised up from the large point of view for protection of fishermen. It is concluded that the Government have to take charge of the remutual insurance in order to develop the fisheries mutual insurance system. 3. The mutual insurance system of fish catch have to be executed in order to guarantee the stable income for fishermen on the base of the amount of money by fish catch in the previous year.

• The Korean Journal of Financial Management
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• v.15 no.2
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• pp.183-210
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• 1998

1975년 1월${\sim}$1996년 12월까지의 기간에서 월별주가수익률 자료를 이용하여 반대투자전략의 경제적 유용성을 검증한 결과 다음과 같은 사실을 발견할 수 있었다. 첫째, 보유기간비정상수익률 사이의 시계열상관분석에서는 18개월 이내의 기간에서 통계적으로 유의적인 시계열상관성을 발견하지 못하였으나 24개월 이상의 기간에서는 통계적으로 유의적인 부(-)의 시계열상관성이 존재하였다. 한편 36개월의 보유기간비정상수익률을 측정하는 경우 시장조정수익률모형보다 시장위험조정수익률모형에서 더 높은 시계열상관성이 관찰되었다. 둘째, 표본증권을 대상으로 하여 시장조정수익률모형에 따라 형성기간의 보유기간비정상수익률을 측정하여 반대투자전략을 수행하는 경우 검증기간의 보유기간비정상수익률이, 패자포트폴리오에서는 1% 수준에서 통계적으로 유의적인 31.1%이었으나 승자포트폴리오에서는 비유의적인 1.1%이었다. 그러나 포트폴리오를 운용하는 과정에서 부담해야 하는 거래비용을 공제하는 경우 36개월간의 보유기간비정상수익률이 21.1%인 것으로 나타나고 있어 경제적인 유용성면에서 한계가 있는 것으로 나타났다. 셋째, 시장조정수익률모형보다 시장위험조정수익률모형이 승자 및 패자포트폴리오의 구성종목에 대한 선별력이 높은 것으로 나타났다. 시장위험조정수익률모형을 이용하는 경우 36개월간의 보유기간비정상수익률이, 패자포트폴리오에서는 1%수준에서 유의적인 120.9%이었으며, 승자포트폴리오에서도 1% 수준에서 유의적인 -36.5%를 보임으로써, 시장조정수익률모형에 기초한 반대투자전략과 비교할 때, 경제적 유용성이 현저히 높은 것으로 나타났다. 넷째, 검증기간에서의 위험변화가 반대투자전략의 투자성과에 상당히 영향을 미치는 것으로 나타났다. 차익포트폴리오에서 위험변화를 고려하는 경우 36개월간의 거래비용공제전 보유기간비정상수익률이 157.4%에서 67.8%로 줄어들었다.

• Journal of Periodontal and Implant Science
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• v.31 no.2
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• pp.465-475
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• 2001

The purpose of this study was to evaluate effect of platelet rich plasma on the treatment of Grade II furcation involvement, with and without porous resorbable calcium carbonate($Biocoral^{(R)}$)in humans by digital subtraction radiography. 15 teeth(control group) were treated with porous resorbable calcium carbonate($Biocoral^{\(R)}$), and 15 teeth(test group) were treated with porous resorbable calcium carbonate($Biocoral^{(R)}$) and Platelet Rich Plasma. The change of bone density was assessed by digital subtraction radiography in this study. The change of mineral content by as much as 5%(vol) could be perceived in the subtracted images. The change of mineral content was assessed in the method that two radiographs are put into computer program to be overlapped and the previous image is subtracted by the later one. Both groups were statistically analyzed by Wilcoxon signed Ranks Test and Mann-whitney Test using SPSS program(5% significance level). The results were as follows: 1. In test group, the radiolucency in 3 months after surgry were significantly increased than 1 month after surgery(p<0.05). 2. In test group, there were no significant difference between 1 month after surgery and 6 months after surgery(p>0.05). 3. In test group, the radiopacity in 6 months after surgery were significantly increased than 3 months after surgery(p<0.05). 4. In control group, the radiolucency in 3 months and 6 months after surgery were significantly increased than 1 month after surgery(p<0.05). 5. In control group, the radiopacity in 6 months after surgery were significantly increased than 3 months after surgery(p<0.05). 6. There were no significant difference between test group and control group at 1 month, 3 months after surgery, but radiopacity in test group were significantly increased than control group at 6 months after surgery(p<0.05). In conclusion, Platelet Rich Plasma can enhance bone density.

• Journal of Bio-Environment Control
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• v.2 no.1
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• pp.16-26
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• 1993

A sundry system is one of popular systems for composting livestock manure, of which main honest is to utilize unlimited, clean, and free solar radiation. A sundry system with a composter of two horizontal screw-type concrete ducts at different height, was constructed and operated for three days for each test in May, 1993, to evaluate its composting performance. Four treatments of the mixture ratio of swine manure and saw dust (manure : sawdust= 1 : 1.25, 1 : 1, 1 : 0.7, 1 : 0.5) were implemented to evaluate the effect of the mixture ratio on degradation of the composting materials of a sundry system with a screw-type composter. Maximum temperature of the composting materials was over 5$0^{\circ}C$ at D1 or D2 (one or two days after operation starts) for each test. Mean C/N ratio and water contents of the materials were reduced by more than 15 and 20％, respectively. Microbial density of each test showed a typical variation with the lapse of the composting time. Mesophilic microorganism seemed to play more important role on degradation of the materials than thermophilic. A sundry system with a screw-type composter can be considered as a feasible system on basis of maturity data. The conclusion was completely reverse from that of Choi et at., although both adopted a sundry system. A further study is recommended to pursue the cause of better performance of the screw-type composter, whether it was due to affirmative weather or more efficient composter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.2055-2061
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• 2009

There can be some variation in the load carrying capacity of high-tension bolt friction joints when oversize bolt holes are made on the base plate and the cover plate. This study performed a static tensile test in order to examine the variation of slip load and slip coefficient according to standard bolt hole and oversize bolt hole in high-tension bolt friction joints. According to the results of the static tensile test, the slip coefficient changed to some degree according to oversize bolt holes on the base plate and the cover plate, but it was somewhat unreasonable to find a pattern in the change. Sliding strength showed a difference of up to 26% between the use of standard bolt holes and the use of oversize bolt holes. Because this exceeds the design sliding strength, however, its effect on the serviceability of joints under service load is insignificant. Thus, if the regulation on oversize bolt holes, which may be inevitable in making steel members, is applied flexibly, we may improve efficiency and economy in the design and construction of structures.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.3
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• pp.256-260
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• 1995

This study was carried out to select economic-crops according to the improvement methods of newly-reclaimed soils. Silage corn, soybean, Job's tears and sweet potato were cultivated under 6 treatments including integrated improvement plot, control plot, compost plot, subsoiling plot, phosphate plot and lime plot on the Songjeong loam from 1985 to 1988. Crop yields and soil physical properties were investigated throughout the experiment. Soil porosity in the sweet potato plots were highest. In case of cultivated years, those of 4th year were lowest. Averaged yield increasing ratios of silage corn, soybean, job`s tears and sweet potato in the integrated improvement plots were 132%, 29%, 49% and 59%, respectively. And that of 5 soil improved treatments for 4 crops were 53%, 15%, 25% and 38%, respectively. After subtraction of the total expenses of soil conditioners, the economical efficiency of soil improvements were clear in the 4 crops except the compost plot of silage corn. That of sweet potato plot was the highest.