• Journal of Soil and Groundwater Environment
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• v.10 no.5
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• pp.37-44
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• 2005

The main object of this study is to develop the infiltration facility that it can be used in grounds, parking areas, roads, pathway, housing etc. As a result, it is much alike in the infiltration method of facility to use permeable concrete, permeable hole and be filled with broken stones. And through this experiment, it was perceived the truth that the state of ground, the groundwater level, buildings around them, the history of submerging and the applicable infiltration facilities are the key. To verify how much the infiltration facility reduce the outflow, we set up the infiltration facility in the test area. In result, it reduced the outflow 89% in 24 mm rainfall, 93% in 12 mm, 51% in 140 mm, 75% in 64 mm and 80% in 54 mm. As the rainfall rate increased, the infiltration increased up to the limited rainfall. And in the limited rainfall, we knew that the infiltration was reduced suddenly. Infiltration is closely related to the state of ground, the rain interval etc. and we will analyze these conditions through the continuous monitoring.

• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.2
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• pp.152-156
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• 2014

The purpose of this study is to compare efficiency of broad spectrum LEDs ($VALO^{(R)}$, Ultradent, USA) with conventional LED curing lights ($Elipar^{TM}$ Freelight 2, 3M ESPE, USA) using a microhardness test. The light curing units used were $VALO^{(R)}$ in three different modes and $Elipar^{TM}$ Freelight 2. The exposure time was used according to the manufacturer's instructions. After cured resin specimens were stored in physiological saline at $37^{\circ}C$ for 24 hours, microhardness was measured using Vickers microhardness tester. The microhardness of upper and lower sides of the specimens were analyzed separately by the ANOVA method (Analysis of Variance) with a significance level set at 5%. At upper side of resin specimens, an increased microhardness was observed in the broad spectrum LED curing light unit with a high power mode for 4 seconds and plasma emulation mode for 20 seconds (p < 0.05). However, at the lower side of resin specimens, there were no significant differences in microhardness between broad spectrum LED curing light unit and conventional LED curing light unit.

• Korean Journal of Construction Engineering and Management
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• v.17 no.2
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• pp.21-30
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• 2016

The current PF project is entirely relying on construction company's credibility. As such, it has increased a negative and bad recognition in domestic real estate economy. In addition, PF experts has a perception that a project's safety of future cash flow profitability is more important than the construction company's credibility. So many PF experts make an effort in order to set aside safe project structure of PF and analyse systematically the risks of the project. In common feasibility study of the PF Project, financial specialists and real estate specialists are forecasting and evaluating the suitability of the project through reviewing the development profit from the project of sales. However, cash flow analysis and evaluation from the perspective of mid-sized construction companies are still in the primary level. Therefore, this study has analysed the current feasibility study and go/no go decision making procedures. Then the authors have a new cash flow analysis method from the perspective of mid-sized construction companies, by improving the feasibility study and go/no go decision making procedures.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.12
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• pp.1653-1661
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• 2007

The research aimed to establish the standard extraction procedure for examining brazilin, the major chromophoric substance of Sappanwood, using GC-MS with the ultimate goal of identifying the sappanwood dye in severely faded archaeological textiles. The amount of brazilin represented by the GC abundance was the largest when acetone was used as the extraction medium, followed by methanol. Shaking plate operated at room temperature was more effective than the waterbath shaker which was operated at $30^{\circ}C$. In both cases, the extraction method which incorporated one hour pre-soaking before the 12 hours of actual extraction resulted in a larger amount of brazilin detection than the extraction procedure without the one hour pre-soaking. In case of water extraction, pH 5 resulted in the most effective pH level for the extraction of brazilin, The best GC-MS parameter for detecting brazilin was to set the column temperature initially at $50^{\circ}C$. gradually increase to $210^{\circ}C$ at a $23^{\circ}C/min$ rate, finally increase to $305^{\circ}C$ at $30^{\circ}C/min$ rate, and hold for 14 minutes, and the MSD scan range at $75{\sim}400m/z$.

• The Korean Journal of Applied Statistics
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• v.21 no.1
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• pp.141-149
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• 2008

Recently we frequently analyze multivariate data with quite large number of variables. In such data sets, virtually duplicated variables may exist simultaneously even though they are conceptually distinguishable. Duplicate variables may cause problems such as the distortion of principal axes in principal component analysis and factor analysis and the distortion of the distances between observations, i.e. the input for cluster analysis. Also in supervised learning or regression analysis, duplicated explanatory variables often cause the instability of fitted models. Since real data analyses are aimed often at multiple purposes, it is necessary to reduce the number of variables to a parsimonious level. The aim of this paper is to propose a practical algorithm for selection of a subset of variables from a given set of p input variables, by the criterion of minimum trace of partial variances of unselected variables unexplained by selected variables. The usefulness of proposed method is demonstrated in visualizing the relationship between selected and unselected variables, in building a predictive model with very large number of independent variables, and in reducing the number of variables and purging/merging categories in categorical data.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.353-358
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• 2003

Recently there has been huge efforts to improve performance in construction process by applying emerging techniques such as the Lean principle, Just-in-time concept and so on. However, little achievement as we expected has come out in reality due to the lack of strategy to set a definite goal of the execution and differences of personal viewpoints on construction productivity. Accordingly, it is the most important to promote the circumstances for the construction process improvement by quantifying the goals of respective unit activity groups. This research explores feasible solutions for the improvement of construction projects performance by combining the six-sigma principle for the generic administrative innovation based on the idea of construction process performance. For this purpose, mutual comparisons of various current approaches are performed in an attempt to establish the advantages in applying six-sigma idea and to provide its fundamental strategy. Furthermore, through a case study with the simulation of applying six-sigma to a unit activity group in construction process, this paper verifies that the overall performance improves as the degree of sigma level gets advanced.

• Progress in Medical Physics
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• v.11 no.1
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• pp.39-47
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• 2000

In Stereotactic Radiosurgery (SRS), there are three imaging methods of target localization, such as digital subtraction Angiography (DSA), computed tomography (CT), magnetic resonance imaging (MRI). Especially, DSA and MR images have a distortion effect generated by each modality. In this research, image properties of DSA were studied. A first essential condition in SRS is an accurate information of target locations, since high dose used to treat a patient may give a complication on critical organ and normal tissue. Hut previous localization program did not consider distortion effect which was caused by image intensifier (II) of DSA. A neurosurgeon could not have an accurate information of target locations to operate a patient. In this research, through distortion correction, we tried to calculate accurate target locations. We made a grid phantom to correct distortion, and a target phantom to evaluate localization algorithm. The grid phantom was set on the front of II, and DSA images were obtained. Distortion correction methods consist of two parts: 1. Bilinear transform for geometrical correction and bilinear interpolation for gray level correction. 2. Automatic detection method for calculating locations of grid crosses, fiducial markers, and target balls. Distortion was corrected by applying bilinear transform and bilinear interpolation to anterior-posterior and left-right image, and locations of target and fiducial markers were calculated by the program developed in this study. Localization errors were estimated by comparing target locations calculated in DSA images with absolute locations of target phantom. In the result, the error in average with and without distortion correction is $\pm$0.34 mm and $\pm$0.41 mm respectively. In conclusion, it could be verified that our localization algorithm has an improved accuracy and acceptability to patient treatment.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.1
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• pp.57-68
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• 2010

The purpose of this study is to analyze the characteristics of environment-friendliness of waterproof materials based on comprehensive experiments on waterproofness in terms of coefficients of permeability, harmfulness of waterproof materials and fish toxicity of Oryzias latipes mortality to verify eco-toxicity of each method of construction and waterproof material, which are to be applied by taking eco-toxicity into account when building ecological flows in upper areas on natural and artificial grounds. As a result, the following conclusions have been reached in this study: 1. In regard of the harmfulness analyzed, each material showed a different result of analytical value in each lab tank. Compared to input water, pH, COD, SS, T-P, and T-N values increased a little, but DO value decreased. The value of turbidity analyzed independent of the water quality standard of aquatic ecosystem set forth by the Ministry of Environment increased a little compared to the value in input water. 2. In the experiment of fish toxicity, compacted quicklime, cement fluid waterproof material, cement mortar waterproof material and bentonite powder were found to have 100% of fish mortality, respectively, and membrane waterproof material showed 83.3% of mortality, indicating strong fish toxicity. Improved asphalt sheet (63.3%) and synthetic rubber sheet (53.3%) were analyzed to have medium fish toxicity, while bentonite sheet (6.7%), Hwang-toh (6.7%) and clay (3.3%) showed relatively lower mortality and fish toxicity. 3. Regarding the analysis on waterproofness in terms of the coefficient of permeability of each waterproof material, improved asphalt sheet, synthetic rubber sheet, membrane waterproof material, cement fluid and mortar waterproof material and bentonite sheet were found impervious in case no leakage takes place in construction. Bentonite powder was found practically impervious based on the analytical results from the experiment done in compliance with weight ratios. So were the clay and Hwang-toh from the experimental results. To sum up such results as found in the experiment mentioned so far, the values of harmfulness and waterproofness analyzed were different in each lab tank, but there was absolutely little correlation with the mortality gained from the experiment on fish toxicity. In the experiment of fish toxicity, environment-friendly waterproof materials were analyzed, and it was found that clay, Hwang-toh and bentonite sheet are highly environment-friendly. In contrast, synthetic rubber and improved asphalt sheets were found to have medium-level environment-friendliness. Also, membrane water-proof materials, compacted quicklime, cement fluid and mortar waterproof material and bentonite powder were analyzed to have low environment-friendliness.

• Journal of the Korean Society of Food Culture
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• v.7 no.4
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• pp.309-321
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• 1992

A study was designed to assess the current status of infant feeding and weaning practice through an retrospective survey on feeding method, a period of weaning and various kinds of weaning food. Analysing a few influential environmental factors while assessing the level of knowledge today's mothers have on infant nutrition. The results are as follows: 1. As random samples for this study, a total of 516 mothers having infants under the age of 3 were surveyed. Among them, 235 were from Seoul and 281 were from Kyongi province (Yongin, Suwon, Bupyong, Poil, Kihung, Ansan(Chungbuk)). 2. Among the infants who fell under the category of normality (Kaup index $15{\sim}18$), the infants from Seoul area amounted to 60.7%, surpassing the percentage of the infants from Kyongi province, 41.9%. The percentage of the infants belong to a group of under nutrition (Kaup index <13) was relatively higher than that of the infants in a group of overnutrition (Kaup index >20). 3. 16.1% of mother surveyed were breast-fed, 54.6% were formula-fed and 29.3% were mixed-fed. The result indicated that the percentage of breast-fed infants of high-educated, working mothers were relatively lower than those of low-educated housewives. 4. Most of the respondents knew the significance or the necessity of supplementary food in terms of weaning. 5. 98.8% of those surveyed responded that the mother's adequate knowledge on weaning was necessary. 70.1% of them replied that they wanted to get various and in-depth information in printed materials such as books or other kinds of publications. They, also showed deep interest in recipe of weaning food. 6. The average period when those surveyed began weaning of their infants was $4.3{\pm}1.8$ months. The tendency of earlier weaning in 3 months was founded among 41.1% of them. About half of the respondents, 52.3%, started weaning of their infants in $4{\sim}6$ months. In overall, 93.4% of them set on weaning in less than 6 months after babies were born. The survey, in addition, revealed an interesting fact that earlier weaning of infants was shown in the group of high-educated mothers. 7. According to the study, finishing period of weaning was $13.3{\pm}5.4$ months on average. Only 38.9% of the respondents ended weaning of their infants in 12 months, the proper period recommended by renowned experts. In general, the infants on formula-feeding finished their weaning later than those on breast-feeding (p<0.05).

• Korean Journal of Adult Nursing
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• v.15 no.3
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• pp.472-482
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• 2003

Purpose: Purposes of this study were to understand the current trends on complementary therapy in relieving chemotherapy-induced nausea and vomiting and to suggest the future research direction. Method: Subjects were selected on CINAHL, MEDLINE, Korean Academy Data Base from 1980 to 2001 which used nausea, vomiting, chemotherapy and complementary therapy as key words in experimental studies. Eight korean articles and twenty-one international articles were analyzed in terms of general characteristics, research methods, and types of complementary therapy. Data were analyzed by using descriptive statistical methods. Result: Since 2000, researchers have more actively used complementary therapy. In subject characteristics, mean age was 35.5 years old, 45% of the researchers were performed with high level of incidence of chemotherapy induced vomiting, 14% of them set limit of consecutive cycle during research, and 65% of them did not comment the selecting criteria of sample. About 60% of them were designed post-test only control group; 35% used INV by Rhodes, 31% used Likert scale, and 24% used VAS for dependent variable. Muscle relaxation therapy was mostly applied for relief of nausea and vomiting. Conclusion: Further studies will be needed to control extrinsic variables affecting nausea and vomiting in research design and to accumulate evidence with studies applying various complementary therapies.