• Journal of Preventive Medicine and Public Health
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• v.28 no.1 s.49
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• pp.103-121
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• 1995

An investigation on psychophysiological health and social well-being of shift workers been carried out on workers of a automobile manufacturing plant in Ulsan, for 1 month from April, 1993. This cross-sectional survey compared shift workers(n=544) with day workers(n=115). Each subject completed a questionnaire about his personal habit, background, shift schedule, sleep and eating patterns, subjective digestive symptom and psychological well-being and distress using the General Well-Being Schedule(GWB) by self administrated questionnaire that was developed for the U.S. Health and Nutrition Examination Surveys (HANES I). Chi-square analysis was used for discontinuous data and the t-test was used for continous data to determine whether differences noted between the two groups. In terms of sleep quality, a greater percentage of shift workers frequently had trouble getting back to sleep once awakend(p<0.01), and a greater percentage of shift workers awakend tired or sleepy frequently more often than day workers(p<0.05). In rating the quality of their sleep, more shift workers rated their sleep fair to poor than day workers, and greater percentage of shift workers felt tired or sleepy at work two or more times per week(p<0.01) and a much higher percentage of shift workers felt tired or sleepy after work every days(p<0.01). In terms of sleep patterns, a much higher percentage of day workers reported uninterrupted sleep per 24hours than shift workers. The shift workers reported different eating patterns from day workers but there were no statistically significant and rate of their appetite. Thirteen percent of day workers reported the best appetite but only 6.6% of shift workers had the best appetite. The gastric complaints is more frequent in shift workers than day workers(p<0.01). Among subscores in General Well-Being Schedule, anxiety, depression, positive well-being and vitality subscale of shift workers were lower than those of day workers(p<0.05) and general health and self control subscale of shift workers were lower than .those of day workers but there were no statistical significant difference. Based on these study result, it could be concluded that the shift work has significant effects on some psychophysiological conditions of the workers.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.1
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• pp.16-25
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• 2012

To calculate the total mass flux that change in dry and flood season in the Yeomha Channel of Gyeonggi Bay, the 13 hour bottom tracking observation was performed from the southern extremity. The value of the total mass flux(Lagrange flux) was calculated as the sum of the Eulerian flux value and stroke drift value and the tidal residual flow was harmonically analyzed through the least-squares method. Moreover, the average during the tidal cycle is essential to calculate the mass flux and the tidal residual flow and there is the need to equate the grid of repeatedly observed data. Nevertheless, due to the great differences in the studied region, the number of vertical grid tends to change according to time and since the horizontal grid differs according to the transport speed of the ship as a characteristic of the bottom tracking observation, differences occur in the horizontal and vertical grid for each hour. Hence, the present study has vertically and horizontally normalized(sigma coordinate) to equate the grid per each hour. When compared to the z-level coordinate system, the Sigma coordinate system was evaluated to have no irrationalities in data analysis with 5% of error. As a result of the analysis, the tidal residual flow displayed the flow pattern of sagging in the both ends in the main waterway direction of dry season. During flood season, it was confirmed that the tidal residual flow was vertical 2-layer flow. As a result of the total mass flux, the ebb properties of 359 cm/s and 261 cm/s were observed during dry and flood season, respectively. The total mass flux was moving the intertidal region between Youngjong-do and Ganghwa-do.

• Journal of the Korean Geographical Society
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• v.31 no.4
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• pp.699-715
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• 1996

This paper examines the cross-sectional development of children's conception of place. Previous research by Piaget and Weil, Jahoda, Daggs has questioned how young children develop the ablity to comprehend place. Oral interview and graphic test were made vy the children at the age of 5-14, in order to attain information on their knowledge, understanding and feeling about place. These data were used ti indentify developmental stages through cluster analysis. The results suggest that young children's conception of place develops with an identifiable 4 stages. There is no significant difference in development of conception of place between the 2nd year of kindergarten and the 1st year of elementary school, or the between the 5th, 6th year of elementary school and 1st, 2nd year of middle school. Rather, the 4th year of elementary school is an important and crucial truning point in the development of children's conception of place. It is concluded that children's conception of place develops in line with Piaget's general cognitive developmental theory in which the pre-conceptual stage ends at age 7 and the concrete-operation stage starts at age 11 to 12.

• Journal of Periodontal and Implant Science
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• v.24 no.1
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• pp.131-143
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• 1994

For maintenance of exposed implant in healthy state, it is necessary to treat the surface of implant fixture and provide the surface adjustable to surrounding tissues. Variable techniques have been introduced such as citric acid and air-abrasive system to treat the failed implant. Although when the rough surface of HA coated implant was exposed to oral environment, the surface treatment method with citric acid or air-abrasive system is effective for removal of bacterial endotoxin, it is unsuccessful to prevent plaque deposition due to difficulty in removal of rough surface of HA coated implant. Thus, in this study the method that removes bacterial endotoxin and makes smooch surface without alteration of surface characteristics was studied. HA coated disc manufactured by IMZ Co. Was treated with high speed diamond bur, low speed diamond bur, stone bur, rubber point, jetpolisher. And then its surface state was examined with profilometer and SEM to evaluate the surface smoothness, and its surface component was analyzed with EDX to evaluate wheter the surface characteristics were altered or not. As a result, following results were obtained. When the surface roughness of each implant disc was measured by profilometer, the group I showed a $R_{max}\;2.11{\mu}m$ and the group II, III, IV, V showed a $R_{max2}\;4.17{\mu}m$, $7.28{\mu}m$, $8.61{\mu}m$ and $39.44{\mu}m$ respectively. That is, surface smoothness was highest in the group I and it has been gradually decreased in the group II, III, IV and V. Under the SEM examination, the group I showed relatively smooth surface and the group II showed slightly rougher surface than the group I due to partially remaining HA particles while most HA particle was removed. The group III and IV showed rough topography due to HA particles that was not grinded, and HA coated surface in group V showed very irregular surface with deep groove and prominence. In cross-sectional view, the group I showed uniform surface, and the group III, IV showed rough surface due to remaining HA particles but the thickness of HA coating was remarkably reduced. The group II has similar pattern in group I, and the group V showed about $40{\mu}m$ thickness although it was not constant. By analysis of surface component with EDX, the group II in which the grinding was effective showed a small quantity of calcium and phosphorous and the group III, IV, in which the grinding was incomplete showed calcium and phosphorus peak. In all experimental group, no other than titanium, aluminum, calcium, phosphorus was observed.

• Tuberculosis and Respiratory Diseases
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• v.62 no.1
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• pp.11-18
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• 2007

Background: Patients with chronic obstructive pulmonary disease (COPD) have often been reported to suffer from depression and anxiety possibly due to the exacerbation, hospitalization and mortality of COPD. However,scarce data are available in Korea. This study assessed degree of depression and anxiety, and evaluated the factors associated with depressive symptoms in COPD. Methods: The cross-sectional data on the lung function measurements, smoking behavior, body mass index (BMI), age, gender, depressive symptoms using Beck Depression Inventory (BDI) and anxiety using the State-Trait Anxiety Inventory (STAI) were evaluated in 72 outpatients with COPD and 50 controls without underling lung diseases from September, 2005 to October, 2006 in the Ewha medical center. Results: 1) The age, body mass index (BMI) and serum albumin levels were similar in the patients and controls. The BDI scores (16(0-37) vs. 12(1-30), p=0.001) and the prevalence of depression (36% vs. 6%, p<0.0001) were higher in the COPD patients than in the controls. In the COPD group, the prevalence of depression increased with increasing GOLD stage (p=0.008). The prevalence was 18%(4/22), in mild cases, 30%(6/20) in moderate cases, 52%(13/25) in severe cases and 60%(3/5) in very severe cases. 2) The SAI and TAI scores were higher in the COPD patients (44(20-67) and 47(20-66)) than in the healthy controls (39(26-65) and 44(33-90)). There were a significant correlation between the depression and anxiety scores (p<0.001). 3) A lower BMI, lower postbronchodilator $FEV_1$, current smoking behavior and severity of COPD were univariately associated with the depressive group in COPD, 4) while multivariate logistic analysis revealed only the severe-to-very severe group (OR 3.9, 95% CI 1.2 to 12.9) to be independently associated with depressive symptoms. Conclusion: COPD is strongly associated with depression and anxiety. Therfore, screening for psychological problems in COPD patients is essential, particularly in patients with severe-to-very severe COPD.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.3
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• pp.366-373
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• 2005

This study was carried out to investigate the self-reported health and eating habit of the elite female adolescent athletes in Incheon. The subjects were 102 elite female athletes of middle and high schools located in Inchon. A self-administered Questionnaire was used for this cross-sectional survey. Statistical analysis by two-way ANOVA was performed to discriminate between the main effects of age (as middle and high school athletes) and sports type, and their interaction. As use of nutritional supplements, 35.8% of the total subjects took vitamin and iron supplements and 62.5% of field and track athletes took vitamin and iron supplements. While mental stress related to exercise was much in fencing ＆gt; shooting ＆gt; field and track ＆gt; swimming athletes, physical burden during training was higher in swimming ＆gt; field and track ＆gt; fencing ＆gt; shooting athletes. More than half of the subjects showed irregular menstrual cycle. As the most severe problem of eating habit, they reported skipping meal ＆gt; overeating ＆gt; prejudiced meal ＆gt; preference to salty and spicy foods. More than half of the subjects skipped meal over three times per week. Fencing and shooting athletes showed very significantly higher frequency of skipping meal and more irregular breakfast time compared to those of other sport types. As for snack, they ate cookies, carbonated drink, chocolate, candy ＆gt; milk, yogurt, ice cream ＆gt; cake, bread, rice cake ＆gt; fried noodle ＆gt; hamburger, pizza. Therefore, nutritional counseling and education by sport type are necessary for health and good eating habit of these elite female adolescent athletes.

• Journal of Korean Society of Forest Science
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• v.86 no.1
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• pp.69-79
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• 1997

The purpose of this study is to acquire essential data to reduce the amount of woody debris resulted from the debris flow. This research examined topographic characteristics of the channelbed affecting generation, movement and storage of woody debris and woody characteristics related to number, sizes, shapes, decay, storage direction to mountainous stream. 1. The number of woody debris had a tendency to increase in proportion to stream width, but it was hardly affected by longitudinal gradient of stream. Especially, the greater amount of woody debris was stored at wide section of the stream with compound channel, and it was found in deposits of channelbed rather than in the present channel. 2. Total woody debris over 10cm in diameter and over 2m in length was 402 units and storage number was 35.3 units per 100m of stream. Average diameter of breast height and length were 14cm and 4m, respectively. The woody debris appeared shorter in length and greater in diameter at down-stream than up-stream. 3. Since woody debris met sediments and bed-materials of great roughness in moving, the greater amount of woody debris without root was found in up-stream and down-stream, but deformed woody debris was discovered in upper stream. Decay of woody debris was more severe in down-stream and woody debris on rotting process was found down-stream. 4. Storage direction of woody debris was mainly parallel to center line of stream, and rate of parallel and perpendicularity was 276 and 126 units, respectively. But, as woody debris storing to the perpendicular direction was unstable, the traveling debris could easily be stored. Therefore, some counterplan was required to prevent the traveling woody debris. 5. Tree species of woody debris was mainly larch, which occupied about two third of total woody debris(256 units). The woody debris of larch is easy to move due to hitting of channelbed materials or lower channelbed fluctuation because the lower part of larch is weaker than its upper part. Therefore, the section of the tree species planting in the riparian vegetation needs much more carefulness.

• Journal of Korean Society of Forest Science
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• v.85 no.2
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• pp.288-299
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• 1996

This is the basic study to investigate the amount of transpirational water loss in thrifty mature Quercus mongolica stand by the heat pulse method. The differences of heat pulse velocity by direction and depth, differences of heat pulse velocity by dominant, codominant and suppressed trees, diurnal changes of heat pulse velocity due to the change of leaf water potential, vapor pressure deficit and radiation, and sap flow path way in sapwood by dye penetration were measured in stems. Finally the amounts of daily and annual transpiration in stand were calculated by the heat pulse velocity. The results obtained were summarized as follows : 1. Relationship between heat pulse velocity(V) and sap flow rate(SFR) was obtained as a equation of SFR=1.37V. 2. The sap flow rate was high in the order of dominant, codominant, and suppressed trees. The daily heat pulse velocity changed with radiation, temperature and vapor pressure deficit. 3. The heat pulse velocity showed the similar diurnal variation as the leaf water potential change. 4. The heat pulse velocity showed the highest value in May(4.0cm/hr in average), the lowest one in July(2.9cm/hr in average). 5. The heat pulse velocity in the same stem presented the highest value in the northern direction, medium in western, and the lowest in southern and eastern. 6. The heat pulse velocity in stem was highest in 0.5cm, medium in 1.0cm, and lowest in 1.5cm depth from the surface of stem. 7. The sap flow path way in stem showed sectorial straight ascent pattern in four sample trees. 8. The amount of sap flow(SF) was presented as a equation of $SF=1.37A{\cdot}V$(A: the cross-sectional area of sapwood, V: heat pulse velocity), and especially SF was larger in dominant tree than codominant and suppressed trees. 9. The amount of daily transpiration was 5.6ton/ha/day, and its composition ratio was 72% at day and 28% at night. 10. The amount of stand transpiration per month was largest in May(168ton/ha/month), lowest in July(125ton/ha/month). The amount of stand transpiration per year was 839ton/ha/year.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.1059-1075
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• 2017

The objective of this study was to evaluate the freezing and thawing resistance of the existing drainage system for leakage treatment of underground concrete structures operating in cold regions. The freezing and thawing test was conducted on 4 types of drainage system specimens to evaluate the freezing and thawing resistance of the drainage system. The freezing and thawing resistance was evaluated on 4 types of Hotty-gel, as a waterproofing material, connection methods and on two methods to fix the drainage board with Hotty-gel on the surface of cement concrete specimen. One cycle of the freeze-thaw testing was 48 hours (24 hours of freezing and 24 hours of thawing), and the temperatures of freezing and thawing were at $-18^{\circ}C$ and $10^{\circ}C$, respectively. Among the 4 types of Hotty-gel connection methods, leakage occurred after 28 cycles (8 weeks) of freeze-thawing only in the Hotty-gel connection method with the 'V' groove applied to the corner of the drainage board. No leakage occurred in the 3 types of Hotty-gel connection methods. In two fixing methods, leakage occurred in the method of fixing the drainage board on the cement concrete specimen using the washer, screw and plastic wall plug. Leakage occurred at one point after 10 cycles (3 weeks) of freezing and thawing. After 28 cycles (8 weeks) of freezing and thawing, leakage point increased to 5 points. As time passed, the leak point was not increased, but the amount of leakage was increased at each leak point. The Hotty-gel connection method with cross-sectional diagonal shape was evaluated to be the highest in the production efficiency considering the production time and manufacturing method of the Hotty-gel connection shape. In the construction efficiency considering the construction time and construction method, the fixing method of air nailer, fixed nail and washer was superior to that of the washer, screw and plastic wall plug.

• Korean Journal of Agricultural Science
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• v.10 no.1
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• pp.129-134
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• 1983

Importance has been increased on farming mechanization in harvesting, handling and processing of forage in Korea. Small grasslands are most spread and popular in Korea in comparison with those of Europe and America. Therefore shearing characteristics of some major forage crops should be studied to be contributed to the basic data to develop a moderate size forage harvester being suitable to the small grassland. They were studied on six kinds of forage crops - reed canarygrass, alfalfa, red clover, orchardgrass, meadow fescue and birdsfoot trefoil-in regarding with moisture content levels and shearing angles. The results were as follows; 1. The increase rate of the linear density in relation to the diameter was greater in red clover than other kinds, and order of increase rate in greatness was reed canarygrass, alfalfa and meadow fescue. 2. The increase rates of the maximum shear forces were high in relation to their cross - sectional area in alfalfa and birdsfoot trefoil with hard stems, and the shear energy were comparatively large in orchardgrass and meadow fescue with soft stems, also reed canarygrass and red clover had high values in both the maximum shear force and the shear energy. 3. The shear energy per unit area or shear strength in relation to moisture content showed concave curves with the minimum values at about 70%w. b. which was in the beginning stage of drying in meadow fescue and orchardgrass, nevertheless reed canarygrass and red clover had convex curves with the maximum values at about 40%w.b. 4. The shear force in relation to the shear angle decreased generally with decrease of shear angle from $90^{\circ}$ to $70^{\circ}$ or $50^{\circ}$.