• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4A
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• pp.238-246
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• 2003

In this paper, we will provide a comprehensive review of radio propagation measurements conducted to date for mobile radio systems at frequency bands used for cellular and personal communications services in microcellular systems. Path-loss results were measured by using narrowband signal and multipath propagations were characterized by wideband measurements. This paper includes unpublished empirical path loss formulas for Oakland city of non-uniform building heights, and presents a comparison with path loss formulas obtained from typical low-rise building environments in order to discuss street grid dependence on route-specific building profile. We will also compare some empirical models developed based on the measurements with a few well-established theoretical prodiction models.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.10
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• pp.1-8
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• 2000

In this paper, positioning schemes based on AOA(Angle of Arrival), TOA(Time of Arrival), and TDOA(Time Difference of Arrival) measurements are reviewed and analyzed. In the case of using those schemes in microcell structure with severe multipath fading and shadowing conditions, the rapid and unpredictable variation of signal level makes it difficult to estimate the position and velocity of mobiles. Therefore, we propose a novel mobile tracking method based on the multicriteria decision making, in which uncertain parameters such as RSS(Received Signal Strength), the distance between mobile and base station, the moving direction, and the previous location are participated in the decision process using aggregation function in fuzzy set theory. Through a simulation, we analysis the impaction of the frequent change of direction and speed of mobiles.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.129-134
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• 1999

Recent construction activities and maintenance of marine facilities have been accelerating to keep up with rapid economic growth in Korea. Marine concrete structures are to salts and chloride from ocean environments. The corrosion of reinforcement steel caused by chloride-penetration into concrete may severely affect the durability of concrete structures. the objective of this research is to develop a durable concrete by investigating the resistance of various corrosion protection systems utilizing different water/cement ratio, silica fumes, corrosion inhibitors, etc. A two-year verification test on various corrosion protection system has been doing in the laboratory. Corrosion investigations on reinforcement steel are now under progress for more than 63 concrete specimen. Corrosion-related measurements include microcell corrosion current.

• Korean Journal of Community Nutrition
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• v.4 no.2
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• pp.149-156
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• 1999

This study was due to investigate the dietary intakes, serum lipids and other hematological indices in female adolescent smokers. The subjects were 85 smokers, whose average pack-year(smoking years on the basis of one pack of cigarettes per day) was 1.26 and 87 nonsmokers who were female high school students in Seoul. An anthropometric measreument was performed and % body fat was also analyzed by the Bioelectrical Impedance Fatness Analyzer(GIF-891). Dietary intakes and food habits were examined through questionnaires and nutrient intakes were analyzed by the Computer Aided. Nutritional analysis program for professional(CAN-pro). Serum TG, HDL-cholesterol and total-cholesterol levels were measured with test kits. Serum glucose, albumin, GOT and GPT were measured by automated dry chemistry system, SPOTCHEM 4410. Hemoglobin, hematocrit, RBC, WBC and MCV were determined by Semi Automated Microcell Counter(F-520). All data were statistically analyzed by SAS PC package program. There was no significant difference in the anthropometric measurements between smokers and nonsmokers. The caloric intake in adolescent smokers tended to be higher than that of nonsmokers but the difference was not statistically significant. In addition, there was no significant difference between smokers and nonsmokers in biochemical indices. Analysis of serum lipids showed that the serum levels of total-cholesterol and LDL-cholesterol of nonsmokers were unexpectedly significantly higher(p<0.05) than those of smokers. Overall results indicate that smoking itself with short pack-year in healthy female adolescent did not seem to influence apparent health and nutritional status.