• Proceedings of the KOR-KST Conference
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• 1995.02a
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• pp.3-32
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• 1995

The Highway Capacity Manual specifies procedures for evaluating intersection performance in terms of delay per vehicle. What is lacking in the current methodology is a comparable quantitative procedure for ass~ssing the safety-based level of service provided to motorists. The objective of the research described herein was to develop a computational procedure for evaluating the safety-based level of service of signalized intersections based on the relative hazard of alternative intersection designs and signal timing plans. Conflict opportunity models were developed for those crossing, diverging, and stopping maneuvers which are associated with left-turn and rear-end accidents. Safety¬based level-of-service criteria were then developed based on the distribution of conflict opportunities computed from the developed models. A case study evaluation of the level of service analysis methodology revealed that the developed safety-based criteria were not as sensitive to changes in prevailing traffic, roadway, and signal timing conditions as the traditional delay-based measure. However, the methodology did permit a quantitative assessment of the trade-off between delay reduction and safety improvement. The Highway Capacity Manual (HCM) specifies procedures for evaluating intersection performance in terms of a wide variety of prevailing conditions such as traffic composition, intersection geometry, traffic volumes, and signal timing (1). At the present time, however, performance is only measured in terms of delay per vehicle. This is a parameter which is widely accepted as a meaningful and useful indicator of the efficiency with which an intersection is serving traffic needs. What is lacking in the current methodology is a comparable quantitative procedure for assessing the safety-based level of service provided to motorists. For example, it is well¬known that the change from permissive to protected left-turn phasing can reduce left-turn accident frequency. However, the HCM only permits a quantitative assessment of the impact of this alternative phasing arrangement on vehicle delay. It is left to the engineer or planner to subjectively judge the level of safety benefits, and to evaluate the trade-off between the efficiency and safety consequences of the alternative phasing plans. Numerous examples of other geometric design and signal timing improvements could also be given. At present, the principal methods available to the practitioner for evaluating the relative safety at signalized intersections are: a) the application of engineering judgement, b) accident analyses, and c) traffic conflicts analysis. Reliance on engineering judgement has obvious limitations, especially when placed in the context of the elaborate HCM procedures for calculating delay. Accident analyses generally require some type of before-after comparison, either for the case study intersection or for a large set of similar intersections. In e.ither situation, there are problems associated with compensating for regression-to-the-mean phenomena (2), as well as obtaining an adequate sample size. Research has also pointed to potential bias caused by the way in which exposure to accidents is measured (3, 4). Because of the problems associated with traditional accident analyses, some have promoted the use of tqe traffic conflicts technique (5). However, this procedure also has shortcomings in that it.requires extensive field data collection and trained observers to identify the different types of conflicts occurring in the field. The objective of the research described herein was to develop a computational procedure for evaluating the safety-based level of service of signalized intersections that would be compatible and consistent with that presently found in the HCM for evaluating efficiency-based level of service as measured by delay per vehicle (6). The intent was not to develop a new set of accident prediction models, but to design a methodology to quantitatively predict the relative hazard of alternative intersection designs and signal timing plans.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.3
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• pp.129-140
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• 1998

In this study two sites were selected to investigate groundwater contamination and spatial relationship between pollution level and its source. One is the Asan area, agricultural district where pollution sources are scattered. The other is the Gurogu area of Seoul city, industrial district where industrial complex and residential areas are located. Groundwater samples collected from these districts were analysis for chemical constituents. The attribute value files of the chemical constituents of groundwater and the spatial layers have been constructed and the pollution properties have been investigated to find out spatial relationships between the groundwater constituents and pollution sources using CIS. Relatively high contents of Si and HCO$_3$ in groundwater from the Asan area reflect the effect of water-rock interaction, whereas high contents of Cl, NO$_3$, SO$_4$and Ca in groundwater from the Gurogu area are due to the pollution of various sources. Pollution over the critical level of Korean Dinking Water Standard has been investigated from 15 sampling sites out of 40 in the Asan area, and 33 sampling sites out of 51 in the Gurogu area. There is pollution of NO$_3$, Cl, Fe, Mn, SO$_4$and Zn in groundwater from the Gurogu area, and that of NO$_3$, SO$_4$and Zn in groundwater from the Asan area. Principal pollution in both areas is NO$_3$contamination. Deep groundwater from the Asan area is not contaminated with NO$_3$except for one site and most of shallow groundwater near the potential point sources such as factory and stock farm is contaminated seriously. Groundwater from the Gurogu area has been already polluted seriously considering the fact of contamination of deep groundwater. This study reports a spatial relationship between the pollution level and pollution source using GIS.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.4
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• pp.228-234
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• 2004

In organic farming, nutrients for the crop production are mostly supplied by compost containing various organic materials. The long-term organic cultivation would result in continuous changes of soil chemical properties and fertility. The aim of this study was to investigate the contribution of long-term organic cultivation to the soil fertility in Korea focusing on the chemical properties of soil. Soil samples were collected from organic farms that had been cultivated for 8-10 years after certification of organic product through the conversion periods of 2-3 years. Thereby each organic farm had acquired optimal cultivating techniques and soil condition. We separated organic farms into three groups by cultivating crops, i.e. leaf vegetables, fruit vegetables and fruit trees. In each group, five representative farms were chosen in order to investigate the relationships between application rate of compost and nutrient contents in soil. The application rate of compost was approximately $10-15Mg\;10a^{-1}$ for the first 2-3 years at the beginning of organic farming and then reduced to a rate of $3-4Mg\;10a^{-1}$ after stabilization of organic matter content in soil with $30-50g\;10a^{-1}$. However, the continuous organic farming for 8-10 years resulted in accumulation of nutrients, especially of P, in soil probably due to the excessive amounts of compost applied. In conclusion, we suggest that the application rate and organic sources of compost should be decided on the basis of P content in soil by soil testing and thereafter the lack of soil N content for crop cultivation should be compensated by crop rotation with such as legumes. This might be an approach to the original meaning of organic farming as an environmental friendly agriculture.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.1
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• pp.15-23
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• 1979

In the first paper of the series the five soil fertility factors were evaluated by means of principal component analysis and varimax method. They are interpreted as representing, 1) skeletal available phosporus status, 2) organnic matter status, 3) salt status 4) base status, and 5) free oxide status. In order to resynthesize such fragmented information for the overall soil fertility evaluation, the method of multiple regression analysis was adopted, using the five factor scores and yield data for Korean paddy soils as independent and dependent variables respectively. As test of linear models with different combinations of independent variables the results of t-test of regression coefficient were revealed that the organic matter status (FII) has no relevance to the yield of paddy and that the free oxides and salt supply has by it self only an insignificant contribution to the yield. The multiple correlation coefficient (R) revealed its multiple regression analysis was as low as 0.43. Introduction of quadratic terms to the linear model bettered the result. Thus multiple correlation coefficient (R) was increased as 0.59. Therefore, a coefficient of determination 0.35 was obtained by a quadratic model with interaction terms among the five fertility constituents. Generally we think that the fertility factor has more contribution to raise the rice yield in paddy and that the failure of yield prediction by fertility factor scores was caused by one of follows; 1) the roughness of the yield inspection, and 2) missextraction of fertility constituents. The second step in this study, assuming that the residuals by multiple regression analysis were due to factors other than soil fertility, we can now proceed to predicting the yield from the field characters with the classified fertility groups by means of Hayashi's theory of quantification No. 1. Such variables as fertility groups (FTYG), water availability (WATER), soil drainage (DRNG), climatic zone (CLIZ), surface soil's stickiness (STCKT), surface soil's dry consistence (DCNST), and surface soil's texture (FTEXT) are taken up as the explanatory variables. The quantification appears reasonable; the well to extremely well in soil drainage, very sticky of surface soil, inefficiency in water availability, coarse texture, and very hard to extremely hard dry consistence in soil are detrimental to the rice yield. The R was as high as 0.90 for the set of variables. But the given explanatory variables in this study were not quite effective in explaining rice yield. The method developed seems to be promising only if properly collected data are available. Conditions that should be satisfied in the yield inspection obtained from common cultivator for the purpose of deriving a prediction equation were put forward.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.1
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• pp.1-14
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• 1979

The fertility which is the combined factor is one of the important capability determiants of paddy soils. In this study, we aimed at attaining a quantitative evaluation of soil fertility and further establishing an objective fertility classification on the basis of the fertility evaluation. The samples used in this series studies were collected from Korean paddy field. They include deltas, flood plains, coastal plains, valley plains, fans and low terraces. On the basis of correlation analysis, factor analysis was applied to a set of 15 variables. As a result of factor analysis, five mutually independent and clearly definable fertility component factors were extracted from the 15 variables for the whole 90 surface soil samples. The fertility status of each sample soil could be objectively designated by the score of the five factors. As a means of summarizing the information obtained, taxonomic distances between all pairs of the samples were computed from these five factor scores further to be subjected to numerical taxonomy. Seven fertility groups were formulated, each of which was characterized by one or more of the fertility components. As this fertility classification was based on the present state of soil properties, it would be useful in pointing to the proper direction of further fertility amelioration and improvement for each group to enhance potential productivity of Korean paddy fields.

• Journal of the Korean Wood Science and Technology
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• v.40 no.6
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• pp.378-388
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• 2012

This study was carried out to investigate the optimum condition for sap exudation of Juglans mandshurica in comparison with Acer mono Max. trees in a site of Inje-Gun, Gangwon-Do, Korea. Amount of sap exudation, air temperature, relative air humidity and tree diameter at breast height (DBH) were monitored for the period of February 1 through March 31, 2008, and correlation analysis of several factors affecting on sap exudation was carried out. Sap exudation from J. mandshurica initiated on Feb. 28 as the same time in case of A. mono and continued for a month, and enhanced in early March compared to around the middle of March for A. mono. The amount of sap of A. mono was linearly proportional to the diameter at breast height (DBH) but there was no apparent relationship for J. mandshurica. As the amount of sap exudation per tree increased then sap exudation per unit DBH was also linearly proportional in both J. mandshurica and A. mono. The amount of sap exudation per unit DBH of J. manshurica were $0.3{\pm}0.1{\ell}/cm$ on average, which was one third times of $0.9{\pm}0.1{\ell}/cm$ for A. mono. During the days of enhanced sap exudation, the atmospheric conditions such as air temperature and relative humidity around J. manshurica trees were very similar with those of A. mono. The minimum temperature was a significant factor affecting the amount of sap of J. mandshurica whereas the range of temperature was the principal factor for A. mono. In conclusion, the sap of J. mandshurica exudated in atmospheric conditions similar to A. mono, but the amount of sap was affected by different atmospheric factors compared to A. mono.

• The Korean Journal of Food And Nutrition
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• v.27 no.5
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• pp.872-880
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• 2014

This study was conducted to assess the characteristics and satisfactions related with facility foodservice for the elderly in the Northern Gyeonggi-do area (Republic of Korea). To accomplish this, a survey was conducted to investigate the general characteristics of the elderly, health information, and satisfaction with the foodservice of a welfare facility in the area. The main sources of health information for both the male and female elderly included 'health professionals' (49.0, 45.7%) and the 'mass media' (34.4, 33.5%), and they were revealed to trust the information from 'health professionals' (65.6, 59.5%), more so than the 'mass media' (19.8, 20.8%). The principal diseases of the elderly were 'hypertension' (27.1%), 'diabetes' (21.9%), 'palsy' (19.8%) in males, and 'hypertension' (32.4%), 'diabetes' (24.9%), 'arthritis' (15.0%) in females. Most male and female elderly indicated the main reasons for skipping a meal to be 'no appetite' (37.5, 53.8%) and 'indigestion'(19.1, 17.3%), respectively. The facility foodservice was used by the male elderly for the reasons of 'irritating to cook' (28.1%), 'to meet a friend' (26.0%), and 'economic' (14.6%), while the female elderly used it for the reasons of 'economic' (25.4%), 'to meet a friend' (23.1%), and 'irritating to cook' (23.1%). The reasons for satisfaction with the facility were subject to 'meal supply' (28.0, 37.2%), 'social exchanges' (20.0, 22.3%), and 'good facilities' (18.7, 18.2%). Regarding the officers and nurses of the facility, 13.3% and 9.3% of males and 8.3% and 12.4% of females indicated satisfaction, respectively. The satisfaction with foodservice influenced the welfare facilities, and providing a successful environment for foodservice requires strengthening of the education of facilities employees to become friendlier. Based on these results, greater efforts should be made to provide meaningful information regarding the facility foodservice for the elderly related to the silver service industry in the Northern Gyeonggi-do area as soon as possible.

• The Korean Journal of Emergency Medical Services
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• v.8 no.1
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• pp.87-104
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• 2004

This study selected the fifth and sixth graders of elementary school in Jeollanamdo who can express their opinions of safety consciousness and understand the items of questionnaire as the population. It selected 10 elementary schools under the supervision of Jeonnam Board of Education and sampled 700 students randomly from 2-3 classes in the 5th and the 6th grade. One preliminary survey was conducted to revise and complement the contents and forms of questionnaire with 70 students of a school from Apr. 1 to 6, 2004 and this study was conducted from Apr. 10 to 30, 2004. Data of this study were collected by explaining the purport of study to subjects after obtaining approval of principal and teacher of the school and distributing questionnaires. Total 700 questionnaires were distributed and 681 were collected (97%) and 602 were used for final analysis except 79 lacking responses. The results of this study are as follows. According to demographical characteristics of subjects, 'male' students were 302(50.%) and 'female' students were 300(49.8%) by sex and 'the 5th graders' were 285(47.3%) and 'the 6th graders' were 317(52.7%) in grade distribution. Residents at 'apartment house' were 406(67.4%) in residence type, 'going to school by foot' was 477 students(79.2%), 'high school graduates' were 297(49.3%) in fathers' education, 'high school graduates' were 366 (60.8%) in mothers' education, 'professional and office workers' were 231(38.4%) in fathers' job, 'full-time workers' were 283(47.0%) in mothers' job, and the number of siblings was one except myself in 343 students(57.0%). Respondents on the level of class showing 'good' were 340(56.5%) and those on the degree of adaptation to school life showing 'active' were 349(58.0%). On the characteristics related to safety education, 360(59.8%) responded it was 'very necessary', on the frequency of safety education at school for last one year, 339(56.3%) responded they had 'once or twice', on the frequency of safety education by parents, 279(46.3%) responded they 'often' had it, on the level of safety practice by parents, 347(57.6%) responded they practiced it 'frequently', on the source of knowledge of safety, 223(37.0%) responded they got it from 'parents, siblings and relatives', on the degree of recognizing the need of safety education textbooks, 295(38.5%) responded 'it was needed', on the recognition of necessity of teacher for safety education, 271(45.0%) answered it was very necessary', and on the recognition of qualification of teacher for safety education, 370(61.5%) answered it was 'paramedic'. The mean score of safety consciousness of subjects was 2.72 (SD. 21) of full score 3, having high score over mean score. According to each area, the area showing the highest safety consciousness was safety of fire(2.83), followed by home safety(2.76) and first-aid treatment(2.76), traffic safety(2.71), play and leisure safety(2.66) and school safety(2.56). Items showing statistical differences in the degree of safety consciousness according to demographical characteristics were sex(t=-3.11, p=.002), education(t=2.33, p=.021) and number of siblings(F=3.729, p=.011). In the difference of safety consciousness between both sexes, 'female' students(2.75) showed higher safety consciousness than 'male' students (2.69), and the former also showed higher safety consciousness than the latter in all six areas of school safety, play and leisure safety, traffic safety, fire safety, home safety and first-aid treatment, and there were statistical differences in the areas of play and leisure safety, traffic safety, fire safety and first-aid treatment. According to the differences of safety consciousness by grade, 'the fifth graders'(2.74) showed higher safety consciousness than 'the sixth graders'(2.70) and the former also showed higher safety consciousness than the latter in all six areas of school safety, play and leisure safety, traffic safety, fire safety, home safety and first-aid treatment, and there were statistical differences in the areas of fire safety and home safety. In the safety consciousness by the number of siblings, 'single son or daughter' (2.78) was highest and their safety consciousness was also highest in all six areas of school safety, play and leisure safety, traffic safety, fire safety, home safety and first-aid treatment, and there were statistical differences in the areas of school safety, fire safety and home safety, There were statistically remarkable differences in degree of adaptation to school life (F=15.349, p=.000) and perceived schooling level(F=9.552, p=.000). According to the degree of safety consciousness related to characteristics of safety education, there were statistical differences at the degree of recognizing the need of safety education(F=9.797, p=.000), degree of safety education at school(F=2.595, p=.006), degree of safety education by parents(F=12.709, p=.000), degree of practicing safety by parents(F=17.579, p=.000), source of knowledge of safety education (F=2,715, p=.044), necessity of safety education textbooks(F=3.972, p=.008), need of safety teacher(F=4.137, p=.006) and qualification standard of safety teacher(F=3.016, p=.029).

• Journal of the Korean earth science society
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• v.28 no.2
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• pp.187-201
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• 2007

The first magnetotelluric (MT) transect across the Korean Peninsula was obtained traversing from the East Sea shoreline to the Yellow Sea shoreline. The MT survey profile was designed perpendicular to the strike of the principal geologic structure of the Korean Peninsula $(N30^{\circ}E)$, so-called 'China direction'. MT data were achieved at 50 sites with spacings of $3{\sim}8km$ along the 240 km survey line. The impedance responses are divided into four subsets reflecting typical geological units: the Kyonggi Massif, the Okchon Belt, the western part of the Kyongsang Basin, and the eastern part of the Kyongsang Basin. In the western part of the Kyongsang Basin, the thickness of the sedimentary layer is estimated to be about 3 km to 8 km and its resistivity is a few hundred ohm-m. A highly conductive layer with a resistivity of 1 to 30 ohm-m was detected beneath the sedimentary layer. The MT data at the Okchon Belt show peculiar responses with phase exceeding $90^{\circ}$. This feature may be explained by an electrically anisotropic structure which is composed of a narrow anisotropic block and an anisotropic layer. The Kyonggi Massif and the eastern part of Kyongsang Basin play a role of window to the deep geoelectrical structure because of the very high resistivity of upper crust. The second layers with highest resistivities in 1-D conductivity models occupy the upper crust with thicknesses of 13 km in the Kyonggi Massif and 18 km in the eastern Kyongsang Basin, respectively.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.254-262
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• 2003

Dental caries has a multifactorial aetiology in which there is an interplay of three principal factors: the host(saliva and teeth), the microflora(dental plaque) and the substrate(diet), and a fourth factor time. There is no single test that takes into consideration all these factors and can accurately predict an individual's susceptibility to dental caries. The risk of dental caries can be evaluated by analysing and integrating several causative factors. The objective of the study was to clarify the relationship between caries activity and the status of caries of primary teeth and the relationship between the quantity of S. mutans in the dental plaque and the status of dental caries. Forty nine children ages 5 were examined with caries indices, Dentocult-SM and quantity of S. mutans. The results were as follows: All the survey results were similar with national means of 5-6 years Korean preschool children. The deft index of subjects was 5.46 and defs index was 9.81. There was 8.6% of negative, 10.9% of mild, 28.1% of moderate and 52.3% of active results at screening strip test. 8.6% was negative, 17.2% was mild, 33.6% was moderate and 40.6% was active in site strip test. The Spearman correlation coefficient was 0.775, and overall kappa index was 0.496 between screening strip test and site strip test. There also was a high correlation between caries incidence, Dentocult-SM test, and quantity of S. mutans. Dentocult-SM test as a caries activity test is a reliable method for measuring the status of dental caries in primary teeth.