• Tribology and Lubricants
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• v.15 no.3
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• pp.248-256
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• 1999

Many tribological components in automobile engine undergo high load and sliding speed with thin film thickness. The lubrication characteristics of the components are regarded as ether hydrodynamic lubrication or boundary lubrication, whereas in a working cycle they actually have both characteristics. Many modem engine lubricants have various additives for better performance which make boundary film formation even under hydrodynamic lubrication regime. Conventional Reynolds equation with the viewpoints of continuum mechanics concerns only bulk viscosity of lubricant, which means that its simulation does not give insights on boundary lubrication characteristics. However, many additives of modern engine lubricant provide mixed modes of boundary lubrication characteristics and hydrodynamic lubrication. Especially, high molecular weight polymeric viscosity index improvers form boundary film on the solid surface and cause non-Newtonian fluid effect of shear thinning. This study has performed the investigation about journal bearing system with the mixed concepts of boundary lubrication and hydrodynamic lubrication which happen concurrently in many engine components under the condition of viscosity index improver added.

• Korean Journal of Pharmacognosy
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• v.21 no.2
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• pp.158-162
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• 1990

As a part of studies on the quality control of crude drug preparation, So-Shi-Ho-Tang, index components of Scutellariae Radix were identified by TLC and quantified by HPLC. Wogonin and baicalein were identified in ethyl ether fraction on silica gel plate with benzene/ethyl acetate (1 : 1, v/v). The content of baicalin was determined by HPLC on ${\mu}-Bondapak\;C_18$ column with 0.5%-phosphoric acid/acetonitrile (73 : 27, v/v). Its recovery rate in the extract granules, compared to the content in the Scutellariae Radix, was $52.1\;{\pm}\;0.7%$.

• Korean Journal of Medicinal Crop Science
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• v.22 no.2
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• pp.91-97
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• 2014

The contents of index components in 5 medicinal crops cultivated at different heights in Andong area. The contents of allantoin in Dioscorea batatas Decne and catalpol in Rehmannia glutinosa Liboschitz were not different by cultivation heights (100 ~ 200m). But the contents of index components in Astragalus membranaceus and Angelica acutiloba Kitagawa were higher in samples cultivated at elevated heights. At 700 m of heights, the contents of formononetin and astragaloside I in Astragalus membranaceus were 1.20 and $201.2{\mu}g/g$, respectively. The contents of decursin and nodakenin in Angelica acutiloba Kitagawa were 68.3 and 4.20 mg/g, respectively. Thus Astragalus membranaceus and Angelica acutiloba Kitagawa are recommended to be cultivated in higher altitude.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.17-22
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• 2016

Alloy 600 widely used in nuclear power plant is susceptible to primary water stress corrosion cracking (PWSCC). It is important to prioritize the inspection of Alloy 600 components using PWSCC susceptibility index. Plant-specific model for the susceptibility index was reviewed. The normalized PWSCC susceptibility index to a reference value is suggested and applied. The result was found to be reasonable.

• Journal of Environmental Impact Assessment
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• v.15 no.1
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• pp.45-52
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• 2006

The purpose of this study is to assess spatiotemporal variation of coastal water quality according to time and location changes. For this we developed numerical marine trophic index base on four water quality components (chlorophyll, suspended solids, dissolved inorganic nitrogen and phosphorus) and applied this index to the water quality data measured in the korean coastal zone for the 7-years period from 1997 to 2003. Water quality data are obtained only at selected sites even though they are potentially available at any location. Therefore, in order to estimate spatial variation of coastal water quality, it is necessary to estimate the unknown values at unsampled locations based on observation data. In this study, we used IDW (Inverse Distance Weighted) method to predict water quality components at unmeasured locations and applied marine trophic index to predicted values obtained by IDW interpolation. The results of this study indicate that marine trophic index and spatial interpolation are useful for understanding spatiotemporal characteristics of coastal water quality.

• Journal of the Ergonomics Society of Korea
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• v.25 no.4
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• pp.51-62
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• 2006

The concept of universal design has recently emerged as an important aspect of product design. Universal design is considerably analogous to ergonomic design in a way that it takes the capabilities and limitations of users into consideration during the product development process. However, relatively few studies have been devoted to reflect the practical use of ergonomic principles on universal design. This research attempts to develop a universal design index for mobile phone design to quantify how well a product complies with principles of universal design. The research also emphasizes on ergonomic principles as a basis of evaluation. A generation of the evaluation items was done by cross-checking among the personal, activity and product components. Personal components consist of human characteristics including age, physique, perceptual capacity, life-style, etc. Activity components were derived from those scenarios of mobile phone use while product components were composed of the parts to which a user interacts. Further analysis systematically generated a universal index from relationship matrices among the three components. The index was then used to test its suitability by applying to the evaluation of mobile phones currently on the market. This study demonstrates a development process through which evaluations can be made possible for universal design. The research suggests an improved approach to the appraisal of how well mobile phones are universally designed based on ergonomic principles.

• Korean Journal of Applied Biomechanics
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• v.26 no.2
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• pp.143-151
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• 2016

Objective: The purpose of this study was to investigate the effect of fatigue induction on ground reaction force (GRF) components, postural stability, and vertical jump performance in Taekwondo athletes. Method: Ten Taekwondo athletes (5 men, 5 women; mean age, $22.30{\pm}2.62years$; mean height, $174.21{\pm}9.20cm$; mean body weight, $67.28{\pm}12.56kg$) participated in this study. Fatigue was induced by a short period of strenuous exercise performed on a motorized treadmill. The analyzed variables included vertical jump performance, static stability (mediolateral [ML], center of pressure [COP], anteroposterior [AP] COP, ${\Delta}COPx$, ${\Delta}COPy$, and COP area), postural stability index values (ML stability index [MLSI], AP stability index [APSI], vertical stability index [VSI], dynamic postural stability index [DPSI]), and GRF components (ML force, AP force, peak vertical force [PVF], and loading rate). To analyze the variables measured in this study, PASW version 22.0 was used to calculate the mean and standard deviation, while a paired t-test was used to evaluate the pre- versus post-fatigue results. Pearson's correlation coefficients among variables were also analyzed. The statistical significance level was set at ${\alpha}$ = .05. Results: Vertical jump performance decreased significantly after the induction of fatigue, while AP COP, ${\Delta}COPx$, COP area, APSI, VSI, and DPSI increased significantly. PVF and loading rate increased significantly after the induction of fatigue, while the postural stability variables (AP COP, ${\Delta}COPy$, COP area, APSI, VSI, DPSI) were similarly correlated with GRF components (PVF, loading rate) after fatigue was achieved (r = .600, $R^2$ = 37%). Conclusion: These results suggest that the induction of fatigue can decrease postural stability and exercise performance of Taekwondo athletes during training and competition sessions.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.6
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• pp.103-111
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• 1995

Drought index calculation based on the principal hydrological parameters, such as rainfall and reservoir storage, can estimate the duration and intensity of drought in irrigation reservoirs. It is difficult to build up a drought criteria since the conditions change variously by the reliability of rainfall. Because of the increasing water demands, it is urgent to prepare a generalized positive countermeasure to overcome drought. Water demands can at calculated but the estimation of drought characteristics, and the effective water management method can be established. The purpose of this study is to obtain a drought index and build up a data-base on the reservoir basins for establishing the fundamental hydrological data-base. This Index can observe the behavior of the WSI(Water Supply Index) and the component indices. The results summarized through this study are as follows. 1. WSI value of zero does not correspond to 100% in average due to the skewness in the probability distributions. 2. WSI is not a linear index; that is, given change in terms of water volume or percentage of average does not result in a proportional change on the WSI scale. 3. WSI is not always between the reservoir and the rainfall index in magnitude. This is only true if the component indices are of opposite sign. If they are of the same sign, the SWSI will often have a mangitude greater than either of the component indices. This is easily understood, because the concurrence of extreme values of the same sign for the two components is rarer than the occurrence of extreme values for either of the two components individually.

• The korean journal of orthodontics
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• v.27 no.6 s.65
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• pp.871-880
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• 1997

Multiple features of occlusion have been combined by epidemiologists in attempts to objectively to determine malocclusion severity and treatment priority. Jenny et al were developed DAI(Dental Aesthetic Index), which is an orthodontic index based on socially defined aesthetic standards. This study aimed to evaluate association between 10 occlusal components of DAI and individual measures of skeletal morphology by use of univariate and multivariate analysis. In addition the relationship between a Dental Aesthetic Index score and skeletal morphology was evaluated. The data for this study were obtained from cephalometric radiographs and dental casts of 182 Korean patients(79 men, 103 women) with permanent dentition who had been accepted for the orthodontic treatment at Department of Orthodontics, Chonbuk National University. The results are as follows: 1. Several occlusal components of DAI(missing, crowding and spacing in the incisal segment, diastema, largest anterior irregularity on upper and lower arch) were not associated with individual measures of craniofacial morphology. 2. Sagittal occlusal components of DAI were associated with anteroposterior skeletal measures. 3. The relation between vertical occlusal components of DAI and vertical skeletal measures was low magnitude. 4. A Dental Aesthetic Index, which is based on several aspects of occlusion, did not identify craniofacial morphology. We can conclude that combination of certain occlusal components of the DAI may be related with specific skeletal morphology; but, this concept could not be accepted generally.

• Journal of Korean society of Dental Hygiene
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• v.4 no.1
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• pp.31-48
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• 2004

Dental caries taking place with milk teeth affects eruption of permanent teeth adversely, and thus, it is very important to prevent dental caries from taking place with a child in maintaining his/her physical, mental and emotional health. In this study as conducted to obtain basic data to be required for development of a program for letting preschool children form a habitual life for oral health and right dietary life, a total 172 children aged 5 years and 6 years were selected from children who lived in Hwasung-si, Kyunggi-do and attended preschools (childrens houses) located there with the consent of their guardians. Then, the weight length index (WLI) and blood components of each child were analyzed, and each relation between the weight length index (WLI) and dental caries of milk teeth and between blood components and dental caries of milk teeth was comparatively examined, and thereby, the following results were obtained. When the dmf rate of each group according to the obesity was examined, it was found to be 87.50% in the under-weight group, 71.20% in the normal weight group and 83.87% in the overweight group. And when the dmft rate of each group was examined, it was found to be 48.43% in the under-weight group, 37.10% in the normal weight group and 47.17% in the overweight group. Also, when the dmft index of each group was examined, it was found to be 3.9 in the under-weight group, 3.0 in the normal weight group and 3.8 in the overweight group. That is to say, the under-weight group and the overweight group having an abnormal weight were found to be higher in all of the dmf rate, the dmft rate and the dmft index than the normal weight group. It could be, therefore, known that normal weight should be maintained in order to prevent dental caries of milk teeth. And, it is thought that a right dietary life habit ensuring intake of balanced nutrients should be formed for maintenance of a normal weight. As a result of examining the relation between nutrient components in blood and dental caries of milk teeth, in the case of children with no dental caries, inorganic nutrient components of blood had a tendency to be a little higher, but no statistical significance was observed therein. Meanwhile, it was found that there was a relation between blood type and the dmft index.