• Journal of the Korean Mathematical Society
• /
• v.38 no.4
• /
• pp.723-761
• /
• 2001

The objects of this paper are to formulated a model for the transport of a chain of radioactive waste products in a fractured porous medium, to devise an effective and efficient numerical method for approximating the solution of the model, and to demonstrated the convergence of the numerical method. The formulation begins from a model in an unfractured (single porosity) medium, passes through a double porosity model in a fractured medium, and ends with a modified single porosity model that takes the relevant time scales of the flow and the nuclear decay.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.1
• /
• pp.40.2-40.2
• /
• 2019

Measuring distances at cosmological scales is one of the most important, yet most difficult to acquire astronomical quantities, allowing astronomers to determine the expansion rate of the universe. Typically, astronomers have sought to find "standard candles" that have a known intrinsic brightness in order to determine their distance. The most well known standard candles are Type 1a supernova and Cepheid variable stars making the so-called "distance ladder". Here we present a method for determining cosmological distances via light travel-time arguments, which can be extended from nearby sources to very high redshift sources.

• Journal of the Korean Physical Society
• /
• v.73 no.12
• /
• pp.1808-1813
• /
• 2018

I develop a transfer matrix algorithm for computing the geometric quantities of a square lattice polymer with nearest-neighbor interactions. The radius of gyration, the end-to-end distance, and the monomer-to-end distance were computed as functions of the temperature. The computation time scales as ${\lesssim}1.8^N$ with a chain length N, in contrast to the explicit enumeration where the scaling is ${\sim}2.7^N$. Various techniques for reducing memory requirements are implemented.

• Journal of applied mathematics & informatics
• /
• v.40 no.5_6
• /
• pp.843-856
• /
• 2022

In this article, we analyze the first order delay dynamic equations with several nonmonotone arguments. Also, we present new oscillation conditions involving lim sup and lim inf for the solutions of these equations. Finally, we give an example to demonstrate the results.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.438-439
• /
• 2011

Substations in Korea are classified into an outdoor steel structure type, an outdoor GIS(Gas Insulated Switchgear) type, an indoor GIS type, an underground GIS type, and a complex GIS type. Before 1970, substations were built in outdoor steel structure types only. In 1980, an 154kV indoor GIS type substation was built for the first time in Pusan. And the first 345kV indoor GIS type substation, the first 765kV full GIS substation were built in 1984 and in 2002 each. In 1998, 154kV indoor type substations were standardized into regular type and urban type which applied steel frames to structures. In 2002, this was re-standardized into five different types in detail. In 2007, hub substations which had high capacity were built in the region of industrial zone and heavy load areas. And 154kV compact substation was developed and standardized by compacting an indoor GIS type substation in 2009. This paper would present a series of substation type transition and application standards for substation types and facility scales.

• Wind and Structures
• /
• v.24 no.2
• /
• pp.185-204
• /
• 2017

High-resolution wind measurements at 2.25 m in height were used to investigate the mean and turbulence properties of an extreme thunderstorm wind event in West Texas. These data were combined with single Doppler scans from the Texas Tech University Ka-band mobile Doppler radars systems (TTUKa) to provide meteorological context over the surface measurement stations for portions of the outflow. Several features characteristic of a severe wind event were noted in the radar data, including a bowing portion of the thunderstorm complex and a small circulation on the leading edge. These features were reflected in the surface wind time histories and provided natural separation between various regions of the outflow. These features also contributed to the peak 1-s gust at all measurement stations. The turbulence characteristics of each outflow region were also investigated and compared. Reduced values of running turbulence intensity and elevated values of longitudinal integral scales were noted during the period of peak wind speed. Larger scales of turbulence within the outflow were also suggested via spectral analysis.

• Journal of Korean Physical Therapy Science
• /
• v.9 no.2
• /
• pp.77-85
• /
• 2002

Patient satisfaction is an important factor in evaluating the quality of care. Patient satisfaction may be used to evaluate provider services and facilities, and used to predict the patient returns to a facility. The patients decision whether the patient returns to a facility or whether the patient recommends the facility to other people may be affected by a variety of factors of patient satisfaction. This study is to develop and test of a translated and modified Goldstein's instrument that measures patient satisfaction among physical therapists patients and clients. A self-administered questionnaire survey was conducted in Seoul, Chung-Joo and Bu-Cheon cities. Survey data was obtained from 743 patients who visited the physical therapy practice at university hospitals, general hospitals and clinics. The instrument developed by Goldstein was used and translated into Korean. Several items were added to the instrument. Patient's opinions of service in each domain measured using 5-point Likert-type scales that ranged from strongly disagree to strongly agree. Principal components analysis with varimax rotation was used to indicate which questions examined similar components of patient satisfaction. Component analysis indicated eight scales (kindness, scheduling, recommendation, convenience of parking, privacy, and waiting time). Different types of validity were established well. The coefficient of reliability (Cronbach alpha =.97) obtained for the instrument was clearly within a desired range.

• Journal of Environmental Impact Assessment
• /
• v.16 no.5
• /
• pp.311-318
• /
• 2007

This study was conducted based on the 115 development projects of residential areas during 2001-2006 to investigate the current status of park green areas. Prior Environmental Review System (PERS) was categorized into regions, scales, and time of the projects, and regression model was used for a statistical analysis. The ratios of greenness of Seoul and Gyunggi province were greater than those of other regions whereas the ratios of greeness of Cheonnam, Chungbuk, and Jeonbuk provinces showed smaller percentage of green areas. Secondly as the scales of development get bigger areas of greenness become larger indicating a large scale residential development projects are favorable for securing green areas. Thirdly the correlation between planned area and green areas, and that between planned population and the ratio of greenness are relatively low (P>0.05). This implies green areas are not a good indicator but a concrete guideline for green areas. Fourthly the ratio of greenness of small scale project is not reached to 10% so that it is recommended to secure over one million $m^2$ areas for development project.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.19 no.2
• /
• pp.230-241
• /
• 1995

The purpose of this study was 1) to investigate the effect of male clothing type and facial attractiveness on the subjects' inferences of occupation for the wearers, 2) to investigate the effect of male clothing type on the inferences of occupational characteristics. The stimuli were composed of 24 color photographs which were made of 6 types of clothing and 18 wearers who were made of 3 levels of facial attractiveness in combination with 6 types of clothing. The subjects were 288 male and 288 female university students. The subjects chose an occupation among 19 occupations presented for 6 types of clothing and the wearers. Also the subjects' inferences of occupational characteristics for the clothing were measured by semantic\ulcornerdiffenential scales. The results were as follows: 1) As a whole, the infered occupation for each of the clothing types was consistent with the expected occupations in this study. "Therefore there were stereotypes about male clothing type. At the same time, the halo effect of facial attractiveness appeared when subjects infered wearer's occupation. 2) The subjects' responses to the semantic-differential scales about 6 types of clothing were factor analyzed to identify the underlying constructs of occupational characteristics. At the result, 4 factors were emerged. The first factor was interpreted to Apperance/ Ability, the second, Indi~iduality, the third, Naivety, and the fourth, Dominancy. 3) The male clothing type influenced on the 3 factors except the Dominancy factor.nancy factor.

• Journal of the Korean Society for Heat Treatment
• /
• v.14 no.6
• /
• pp.336-344
• /
• 2001

For the establishment of the world wide unified scales of the Rockwell hardness test with conical indenters, round robin test was carried from 1998 to 2000. The pilot laboratory was MPA-NRW and 12 laboratories from 11 countries participated In this RRT. Rockwell hardness of 74 specially prepared blocks was measured for the scales of C, A, D, 45N, 30N, and 15N and the results were compared. It was found that the geometric form of indenter affects on the results very significantly and standardization in the measurement and evaluation of indenter should be established in short time for the reliable hardness measurement. KRISS showed good results in general for all of the ranges except 15N scale which showed relatively large difference compare to the mean value. It was concluded that poor control in loading velocity of the dash pot was the major reason.