• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.21 no.5
• /
• pp.81-96
• /
• 2018

The purpose of this study is to analyze the characteristics of vegetation changes and structures in the buffer green zone of Sihwa Industrial Complex and propose environmental, ecological and multi-functional vegetation management directions. The density of the Pinus thunbergii decreased from $23.1trees/100m^2$ in 2006 to $9.6trees/100m^2$ in 2017 due to the influence of thinning works. Its green volume increased from $0.97m^3/m^2$ to $2.02m^3/m^2$, contributing to the improvement of the atmospheric environment and promotion of biodiversity. The density of deciduous broad-leaved trees at the top maintained at $18{\sim}21trees/100m^2$. In the areas where the understory vegetation was removed, Pueraria lobata spread as an invasive plant and disturbed the forest. In the areas where the understory vegetation was not removed, various native plant species including the Rhus javanica and Celtis sinensis were introduced and contributed to the development of a forest in a multiple structure. There was a concern with the spread of Robinia pseudoacacia which developed into understory vegetation in Pinus thunbergii forest and some canopy forest. The study proposed vegetation management directions for the back, top and front side according to the physical structure of large-scale buffer green zone formed in a long linear form and the usage characteristics of adjacent land.

• Journal of Environmental Health Sciences
• /
• v.38 no.6
• /
• pp.503-509
• /
• 2012

Objectives: This study was performed in order to evaluate the generation characteristics of airborne bacteria and fungi while operating a household humidifier, in consideration of user habits. Methods: Microbial samples were collected in a closed chamber with a total volume of 2.76 $m^3$, in which a humidifier was operated according to experimental strategies. A cultivation method based on the viable counts of mesophilic heterotrophic bacteria and fungi was performed. Experimental strategies were divided into three classes: the type of water in the water reservoir (tap water, cooled boiled water); the frequency of filling the reservoir (refill every day, no refill); and the sterilization method (sterilization function mode, humidifier disinfectants). Results: Significant increases in the concentration of airborne bacteria were observed while the humidifier was in operation. The concentration had increased to 2,407 $CFU/m^3$ by 120 hours when tap water filled the reservoir without any application of sterilization, while for cooled boiled water, it was merely 393 $CFU/m^3$ at a similar time point. Usages of disinfectant in the water tank were more effective in decreasing bioaerosol generation compared to sterilization function mode operation. Generation characteristics of airborne fungi were similar to those of bacteria, but the levels were not significant in all experiments. Calculated exposure factor can be used as an indicator to compare biorisk exposure. Conclusion: This study identified the potential for bioaerosol generation in indoor environments while operating a household humidifier. User practices were critical in the generation of bioaerosol, or more specifically, airborne bacteria. Proper usage of a humidifier ensures that any biorisks resulting from generated bioaerosol can be prevented.

• Convergence Security Journal
• /
• v.7 no.3
• /
• pp.1-6
• /
• 2007

It is important to manage and correctly evaluate the performance of server in order to improve he performance of server. That is, with the aim of finding whether resources are properly utilized, it is a method to improve both software and hardware aspects. Conventional method in evaluating the server performance involved installing software between server and client and generating the load and by simulating the process, it evaluated the handing efficiency of work load generated per packet volume. Therefore, this paper aims to pro-vide precise measurement method by distinguishing the characteristics of web server and the users' usage pattern and by evaluating the work load management through applying various standards. Specially, it presents the evaluation method from web service of personal and business.

• Structural Engineering and Mechanics
• /
• v.65 no.4
• /
• pp.491-504
• /
• 2018

Because of sandwich structures with low weight and high stiffness have much usage in various industries such as civil and aerospace engineering, in this article, buckling and free vibration analyses of coupled micro composite sandwich plates are investigated based on sinusoidal shear deformation (SSDT) and most general strain gradient theories (MGSGT). It is assumed that the sandwich structure rested on an orthotropic elastic foundation and make of four composite face sheets with temperature-dependent material properties that they reinforced by carbon and boron nitride nanotubes and two flexible transversely orthotropic cores. Mathematical formulation is presented using Hamilton's principle and governing equations of motions are derived based on energy approach and applying variation method for simply supported edges under electro-magneto-thermo-mechanical, axial buckling and pre-stresses loadings. In order to predict the effects of various parameters such as material length scale parameter, length to width ratio, length to thickness ratio, thickness of face sheets to core thickness ratio, nanotubes volume fraction, pre-stress load and orthotropic elastic medium on the natural frequencies and critical buckling load of double-bonded micro composite sandwich plates. It is found that orthotropic elastic medium has a special role on the system stability and increasing Winkler and Pasternak constants lead to enhance the natural frequency and critical buckling load of micro plates, while decrease natural frequency and critical buckling load with increasing temperature changes. Also, it is showed that pre-stresses due to help the axial buckling load causes that delay the buckling phenomenon. Moreover, it is concluded that the sandwich structures with orthotropic cores have high stiffness, but because they are not economical, thus it is necessary the sandwich plates reinforce by carbon or boron nitride nanotubes specially, because these nanotubes have important thermal and mechanical properties in comparison of the other reinforcement.

• Journal of the Korean Society of Costume
• /
• v.50 no.8
• /
• pp.99-111
• /
• 2000

The purposes of this study were to segment the elderly women's apparel market according to their benefits sought and to develop the profiles of each segment. Questionnaire survey was done to 500 elderly women aged over 55 in Chonbuk province from Mar. 1. to Mar. 15, 2000, and 360 questionnaires were used. Frequencies, percentages, means, factor analysis, cluster analysis, $\chi$$^2$-test, and ANOVA were done with SPSS Win+. Duncan's Multiple Range test was followed. The factors of clothing benefits ere consisted of fashion, brand loyalty, economy, practicality, activity, and utility. The elderly women segmented into 4 groups of the reasonability pursuit, th economy & practicality, the benefit unconscious, and the fashion & brand pursuit. The fashion information sources were divided into mass communication-dominated source and point-of-purchase & consumer-dominated source. The factors of store patronage criteria were divided into product assortment, convenience, and additive service. The economy and practicality pursuit selected their clothing with the help of others, used any kind of information sources less, considered convience of the store more, shopped at traditional market, group size was the biggest, was the oldest, and educated less. The reasonability pursuit selected their clothing by themselves, used all kind of information sources, considered many facets of stores, shopped at department store, was younger, healthier, educated more, and lived with husband more. The benefit unconscious spent less money to their clothing, lower usage of information sources, selected their clothing with the help of others, considered all facets of stores less, shopped at moderate or volume zone apparel market or traditional market, was older, healthy, and involved the widowed more. The fashion and brand pursuit spent more money to clothing, considered the product assortment or additive service of store more, shopped at department store, and selected their clothing by themselves, group size was the smallest, was younger educated more, healthy, and showed a tendency of living with husband.

• Journal of the Korean School Mathematics Society
• /
• v.2 no.1
• /
• pp.55-66
• /
• 1999

In mathematics education, teaching-learning activity can be divided largely into the understanding the mathematical concepts, derivation of principles and laws acquirement of the mathematical abilities. We utilize various media, teaching tools, audio-visual materials, manufacturing materials for understanding mathematical concepts. But sometimes we cannot define or explain correctly the concepts as well as the derivation of principles and laws by these materials. In order to solve the problem we can use the computer. In this paper, ′the process of the length of curve being equal to the sum of the vectors when intervals get smaller′ and ′the process of calculating volume of spinning curve by using definite integral.′ Using the computers is more visible than other educational instruments like blackboards, O.H.Ps., etc. Also it can help students with solving mathematical problems intuitively. Consequently more effective teaching-learning activity can be done. Usage of computers is the best method for improving the mathematical abilities because computers have functions of the immediate reaction, operation, reference and deduction. One of the important characters of mathematics is accuracy, so we use computers for improving mathematical abilities. This paper is about the program focused on the part of "the application of definite integral", which exists in mathematical curriculum the second and third grade of high school. When this study is used for students as assisting materials, it is expected the following educational effect. 1. Students will have precise concepts because they can understand what they learn intuitively. 2. Students will have positive thought by arousing interests of learning because this program is composed of pictures, animations with effectiveness of sound. 3. It is possible to change the teacher-centered instruction into the student-centered instruction. 4. Students will understand the relation between velocity and distance correctly because they can see the process of getting the length of curve by vector through the monitor. For the purpose of increasing the efficiencies and qualities of mathematics education, we have to seek the various learning-teaching methods. But considering that no computer can replace the teacher′s role, teachers have to use the CIA program carefully.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.8
• /
• pp.595-604
• /
• 2016

This study discusses the sustainable development of the compact city. The problems of urban sprawl have long been recognized. Urban sprawl results from the confluence of several factors: the lure of cheap open land outside the city, advances in transportation, the ready availability of capital to buy property, the increase in the number of real estate developers and the mass production of housing. The term compact city has the opposite connotation to urban sprawl. Compact cities provide a more energy efficient and less polluting environment, because dwellers within them live closer to shops and work and can easily walk, bike or take public transport. In other words, the compact city has the objective of facilitating the integration of the different functions through the intensive development of various facilities, such as residences, commerce, businesses and of improving the efficiency of urban energy usage by decreasing the volume of traffic.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.3
• /
• pp.160-166
• /
• 2014

In this research, as a measure of reducing energy lost through external wall, we used Glass Hollow Micro Sphere (HMS) to improve insulation performance to structural concrete. The following is a result of experimenting concrete using HMS. As usage of HMS, decrease in slump arose and it is judged as a need of using superplasticizer. Replacement ratio increasing more and more, amount of air showed tendency to decrease and compressive strength decreased for interfacial adhesion had not been formed. as replacement ratio and unit volume decreased. It appears that thermal conductivity decreased about 30.0~46.5 percent as compared with normal weight concrete.

• Journal of Korea Port Economic Association
• /
• v.27 no.3
• /
• pp.231-245
• /
• 2011

Pyeongtaek Port is becoming a specialized for importing or exporting cars. In 2010, Pyeongtaek Port became the major port, out of the 31 ports in Korea, for import and export of cars. Usage of this port was especially high for imported cars. In 2011, more than 1 million cars are expected to be imported or exported via Pyeongtaek Port. This research analyses the factors for selecting Pyeongtaek Port for imported cars and recommendations required to improve Pyeongtaek Port. To do this, questionnaires were given to 14 imported car companies that currently, July 2011, use Pyeongtaek Port and used AHP criteria to asses the importances of each factors. According to this research, the most important determinant for the use of Pyeongtaek Port is 'Port Location' followed by 'Port Cost', 'Port Facility', 'Port Service', 'Port Marketing' and 'Port Cargo Volume', in the order of importance. Also, imported car companies say that the factor in need for the most urgent improvement is 'Port Facilities' in Pyeongtaek Port.

• Journal of Korea Technology Innovation Society
• /
• v.14 no.3
• /
• pp.647-663
• /
• 2011

Company's interest in the work place training and investment has been growing continuously because the talent of human resource is the competitiveness itself in the knowledge based society. However, corporate training programs mainly have focused on large companies and SMEs despite the economic business volume have been treated too lightly so far. This paper regards corporate training programs with one of the methods for SMEs innovation and proposes the smart learning in the smart device diffusion. Concretely, this paper analyzes the utilization intention, each attribute and level in smart learning characteristics using conjoint analysis. The result shows that SMEs have positive response for smart learning acceptance and SMEs consider significantly the usage fee type and location with the difference between regular employee and administrator. Specially, interactive communication and customized contents are preferred in the training type. Smart learning can be used as strategic means in supporting the value innovation and enhancing the absorptive capacity in SMEs innovation process.