• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.22 no.3
• /
• pp.135-149
• /
• 2017

Microplastics are fractions of plastics less than 5 mm in size and can be divided into artificially manufactured primary microplastics and physically or chemically decomposed secondary microplastics. In this study, the emission source of microplastics made by the human activities is defined as the primary source of microplastics. And the primary sources of microplastics were summarized by using the literature and the emission potential of each source was estimated. As a result, this study showed that 63,000 to 216,000 ton/year of microplastics were discharged into the environment. Among primary sources, transport, tyre dust, and laundry were the major primary sources.

• Journal of Korean Society for Atmospheric Environment
• /
• v.17 no.2
• /
• pp.119-131
• /
• 2001

A total of 328 ambient PM-10 samples was collected by a PM-10 high volume air sampler during the periods of February 1997 to February 1999 from Kyung Hee University at Suwon Campus. The samples were analyzed for their bulk chemical compositions(Cu, Fe, Pb, Zn, Al, $Na^{+}$, $NH_{4}^{+}$, $K^{+}$, $Ca^{2+]$, $Mg^{2+}$, $Cl^{-}$, $NO_{3}^{-}$, and $SO_{4}^{2-}$ by both an atomic absorption spectrophotometer and an ion chromatograph. The purpose of this study was t develop a receptor methodology for quantitative assessment of PM-10 sources. The data obtained from this study were ex-tensively examined using the target transformation factor analysis(TTFA) and the chemical mass balance (CMB). When TTFA was initially applied seasonal basis. five sources(such as automobile-related, sulfate-related, incine-ration, soil and combustion-related) were identified both during winter and fall. Since the total number and the type of sources were resolved by TTFA for the four seasons, CMB was employed to cross-check the results of TTEA. The total of six source categories identified by TTEA was intensively investigated on the basis of source profiles acquired from various source libraries established both in Korea and abroad. The results of this study showed the applicability of two popular receptor models as a new methdology for quantitative assessment PM-10 sources in Korea. Seasonally segmented data sets with the combined application of TTFA and CMB yielded a physically reasonable source apportionment result and provided a mean to increase the number of potential sources. Furthermore, this study suggested the possibility of the CMB application to ambi-ent data from Korea after identifying potential sources through traditional factor analysis.

• Journal of the Korean Mathematical Society
• /
• v.35 no.3
• /
• pp.503-525
• /
• 1998

In the theory of retrial queues it is usually assumed that the flow of primary customers is Poisson. This means that the number of independent sources, or potential customers, is infinite and each of them generates primary arrivals very seldom. We consider now retrial queueing systems with a homogeneous population, that is, we assume that a finite number K of identical sources generates the so called quasi-random input. We present a survey of the main results and mathematical tools for finite source retrial queues, concentrating on M/G/1//K and M/M/c//K systems with repeated attempts.

• 한국방재학회:학술대회논문집
• /
• 2008.02a
• /
• pp.775-778
• /
• 2008

In general, forecast tsunami heights announced for tsunami warning are computed by using a linear tsunami model with coarse grids which leads the underestimation of inundation area. Thus, an accurate tsunami inundation map corresponding to the forecast tsunami height is indispensible for an emergency evacuation plan. A practical way to construct a relatively accurate tsunami inundation map was proposed in this study for the quantitative forecast of inundation area. This procedure can be introduced as in the followings: The fault dislocations of potential tsunami sources generating a specific tsunami height near an interested area are found by using a linear tsunami model. Based on these fault dislocations, maximum inundation envelops of the interested area are computed and illustrated by using nonlinear inundation numerical model. In this study, the tsunami inundation map for Imwon area was constructed according to 11 potential tsunami sources, and the validity of this process was examined.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.06a
• /
• pp.343-346
• /
• 2006

Although renewable energy sources are more environmentally friendly than fossil energy sources, it is far more costly, considering current technological standards. It would not present many competitive advantages in the power market. If the renewable electricity is viable in the market, the government should take 'visible' actions to compensate production costs. Popular policies, such as Feed-In-Tariff and Renewable Portfolio Standards, can help to attract investors into generators of renewable electricity. But presently, they are mainly financed through a undifferentiated increase of electricity bills and occasionally confronted with the opposition of the electricity consumers. And most policies tend to focus on increasing the supply of renewable electricity with little consideration toward elevating the motivation of consumers. This study evaluates the potential of environmentally friendly energy consumption and examines the 'green pricing' program which realize the potential.

• Applied Chemistry for Engineering
• /
• v.29 no.1
• /
• pp.1-9
• /
• 2018

Microalgae is considered as one of environmentally sustainable and potential feedstocks to produce biodiesels. However, recent studies on life cycle assessments (LCA) of microalgal buidiesels have shown that energy requirement is not small to produce biodiesel from microalgae, especially during cultivation stage. The costs for carbon sources, nutrients like nitrogen or phosphorous, and water for cultivation can contribute up to 80% of the total medium costs. In the present article, recent trends on the utilization of several promising nutrient sources such as municipal wastewaters, organic fertilizers, combustion exhaust emissions and organic solid wastes were reviewed, and the potential strategies to be used as substitutes of artificial culture media, especially for the biodiesel production, were discussed.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.1
• /
• pp.113-118
• /
• 2009

Grounding systems set the reference voltage level of electric circuits and suppress the Ground Potential Rise (GPR) by flowing fault currents to the ground safely. There are several parameters which evaluate the performance of grounding systems as ground resistance, touch voltage and step voltage. The touch and step voltages, which is called "risk voltage", are especially important to ensure the safety of human body. This paper dealt with the influence of current sources with the different frequency components on the touch and the step voltages. Three types of current sources as commercial frequency, square wave, and surge with the fast risetime of $50\;ns{\sim}500\;ns$ were used to analyze the risk voltages in a grounding system. The risk voltages showed remarkable difference in the same current amplitude depending on the current sources, and increased linearly with the current amplitude in the same current source. From the experimental results, it was confirmed that the risk voltages can be evaluated by a small current application in large-scale grounding systems and the possible largest risk voltage can be calculated by a surge current with the risetime of 200 ns or a current source with the same frequency component as the surge current.

• The Journal of the Korea Contents Association
• /
• v.11 no.10
• /
• pp.217-233
• /
• 2011

In this study, we have examined how the potential users of IT convergence product use the external information sources for purchasing decision focusing on a case of smartphone. Although the specifications and price of IT convergence products, such as smartphone, tablet pc, and smart TV, are considered as major criteria for purchasing decision, the competitiveness of these factors have disappeared as many companies launch similar products in the market. External information sources play a significant role to differentiate the alternatives by offering value-added experience information. The effect of external information sources becomes stronger for experience and high-involvement product whose performance can be evaluated through only users' direct experience. In this study, we categorized the external information sources for smartphone into five; company ads, personal network, expert group, consumers, and media. Through an empirical study with potential smartphone users, we verified how these external information sources affect users' purchasing decision in the perspective of the perceived attributes of information source, quality of information, and individual's characteristics based on self-regulatory theory.

• Nuclear Engineering and Technology
• /
• v.43 no.5
• /
• pp.437-446
• /
• 2011

Siting criteria for nuclear power plants require that faults be characterized as to their potential for generating earthquakes, or that the absence of the potential for these occurrences be demonstrated. Because the definition of active faults in Korea has been applied by the deterministic method, which depends on the numerical age of fault movement, the possibility of inherent uncertainties exists in determining the maximum earthquake from the fault sources for seismic design. In an attempt to overcome these problems this study suggests new criteria and a probabilistic quantitative diagnostic procedure that could estimate whether a fault is capable of generating earthquakes in the near future.

• Journal of Distribution Science
• /
• v.20 no.11
• /
• pp.89-98
• /
• 2022

Purpose: Increasing competition in the higher education sector has prompted universities to enhance their marketing efforts and understand their potential customers. The study aims to explore how information sources are used and changed among prospective Vietnamese students during the decision-making process. Research Design, Data, and Methodology: This study undertakes a longitudinal study involving multiple rounds of data collection to better understand the decision-making process of prospective students. Data was collected from 12th -grade students in Vietnam through two rounds of quantitative surveys with 251 students and one round of qualitative interviews, spanning the duration of their senior year. The three stages of the decision-making process correspond to the three stages of pre-purchase period. Results: Most students decide that attending open days, taking career assessments, and looking up information online are the most important information sources to consider. The WOM sources are more important in the early stages, while university-generated sources and events are important in the later stages. Conclusion: Implications from this study may contribute to the design of more effective marketing communications campaigns as university marketers gain a better understanding of the distribution of information sources utilized for each specific stage of the decision-making process.