• Journal of Preventive Medicine and Public Health
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• v.42 no.4
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• pp.231-236
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• 2009

Objectives : This study was conducted to determine the appropriate sampling time of the salivary stress markers, chromogranin A (CgA) and cortisol as objective indices of job stress assessment in adult females. Methods : The subjects were 20${\sim}$39-year-old women (13 office workers, 11 sales-service workers, and 11 college students) who were eligible for the study and free of acute and chronic medical conditions. Salivary CgA and cortisol levels were determined by enzyme-linked immunosorbent assay (ELISA). Saliva samples were collected (2 $m{\ell}$ each) at 7:00, 8:00, 10:30, 12:00, 17:30, and 22:30 on a typical day. Salivary CgA and cortisol levels, according to sampling time, were compared among the three groups using general linear model. The full version of the Korean Occupational Stress Scale (KOSS), which includes socioeconomic characteristics, health behavior, workrelated characteristics, and BMI, was used to access the subjects' job stress. Multiple regression analysis of the job stressors identified by the KOSS was performed on salivary CgA and cortisol levels. Results : The salivary CgA level peaked at 7:00 (time of awakening), then decreased and were maintained at a low level throughout the day, and increased slightly at 17:30. The salivary cortisol level increased steeply within the 1st hour after awakening, followed by a gradual decrease by 12:00, and was then maintained at a low level throughout the day. The salivary cortisol levels of subjects who worked ${\leq}$5 days per week and graduated from the university were significantly lower at 8:00 (p=0.006). The salivary cortisol levels of non-smokers were significantly lower at 7:00 p=0.040) and 8:00 (p=0.003) compared to smokers. There were no significant differences in salivary CgA and cortisol levels at 10:30 and 12:00 in general characteristics. The regression coefficients on salivary CgA level were significant with interpersonal conflict at 17:30 and job insecurity at 22:30. Regression coefficients on salivary cortisol level were significant with organizational system and total job stressors at 17:30. Conclusions : We suggest that the appropriate sampling times for the salivary stress markers, CgA and cortisol, are at 7:00 (time of awakening), 8:00 (1 hour after awakening), 17:30 (early evening), and 22:30 (before sleep).

• Korean Journal of Food Science and Technology
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• v.48 no.6
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• pp.597-603
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• 2016

This study aimed to explore the protective effect of Gastrodia elata (GE) in an HCl/ethanol induced acute gastritis model by differing the steaming time. The samples GE1 (GE by steaming for 1 time) and GE9 (GE by steaming for 9 times), were selected based on the results of HPLC analysis, free radical scavenging activities, and total phenol and flavonoid contents. To evaluate the anti-inflammatory effect of GE, ICR mice were divided into 5 groups; normal mice (Nor), gastritic mice with distilled water (Con), gastritic mice with 100 mg/kg GE1, gastritic mice with 100 mg/kg GE9 and gastritic mice with 10 mg/kg sucralfate (SC). HCl/ethanol-induced gastric mucosal injury was markedly improved by GE9 treatment as observed during histological evaluation. The increased reactive oxygen species levels in the serum were diminished by GE9 treatment. Furthermore, peroxynitrite levels of the stomach tissue were decreased in the GE9-treated group. The analyses of stomach proteins indicated that GE9 treatment effectively reduced inflammatory cytokine levels as compared to that by GE1 treatment. These results suggest that GE9 improves health during acute gastritis.

• The Journal of the Korea Contents Association
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• v.15 no.11
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• pp.467-485
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• 2015

The market share of private brand(PB) is growing at a rapid pace. Based on the previous studies, consumers pay more attention to the extrinsic cues when they buy the PB products. This paper proposes an integrated model to examine how the retailer credibility which is one of the important extrinsic cues affects perceived quality variation, value consciousness, attitude to PB, and PB product purchase intention. Also, familiarity with PB is regarded as a moderating variable that can interact with retailer credibility. An analysis of 199 useable questionnaires found that retailer credibility has a significant impact on the attitude to PB, directly and indirectly. Further, the moderating effect of familiarity with PB was significant. For this, we interpret that when consumers are more familiar with the private brand, they tend to have few bias toward the quality of PB. These findings provide several effective strategies for the development of PB, such that retailers must improve consumer's familiarity with PB via various promotions like free samples or testing events. Academic and practical implications of the study findings and future research directions are also discussed.

• Journal of Life Science
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• v.23 no.7
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• pp.926-932
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• 2013

Glutamine and serum are essential for cell survival and proliferation in vitro, yet the signaling pathways that sense glutamine and serum levels in endothelial cells remain uninvestigated. In this study, we examined the effects of glutamine deprivation and serum starvation on the fate of endothelial cells using a human umbilical vein endothelial cell (HUVEC) model. Our data indicated that glutamine deprivation and serum starvation trigger a progressive reduction in cell viability through apoptosis induction in HUVECs as determined by DAPI staining and flow cytometry analysis. Although the apoptotic effects were more predominant in the glutamine deprivation condition, both apoptotic actions were associated with an increase in the Bax/Bcl-2 (or Bcl-xL) ratio, down-regulation of the inhibitor of apoptosis protein (IAP) family proteins, activation of caspase activities, and concomitant degradation of poly (ADP-ribose) polymerases. Moreover, down-regulation of the expression of Bid or up-regulation of truncated Bid (tBid) were observed in cells grown under the same conditions, indicating that glutamine deprivation and serum starvation induce the apoptosis of HUVECs through a signaling cascade involving death-receptor-mediated extrinsic pathways, as well as mitochondria-mediated intrinsic caspase pathways. However, apoptosis was not induced in cells grown in glutamine- and serum-free media when compared with cells exposed to glutamine deprivation or serum starvation alone. Taken together, our data indicate that glutamine deprivation and serum starvation suppress cell viability without apoptosis induction in HUVECs.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.3
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• pp.220-225
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• 2013

The adsorption characteristics of phenol by the powdered activated carbon (PAC) were investigated by series of batch experiments. The pseudo-second-order model described the adsorption kinetics adequately with correlation coefficients over 0.999, indicating chemical adsorption as the rate-limiting step. The kinetic rate constants were from 0.55 to 19.81 mg $mg^{-1}min^{-1}$. The adsorption isotherm followed the Langmuir isotherm, indicating the homogeneous mono-layer adsorption onto the surface of the adsorbent. The values of activation energy, enthalpy and entropy were 17.44 kJ $mol^{-1}$, -8.26 kJ $mol^{-1}$ and -18.94 J $mol^{-1}K^{-1}$, respectively. The Gibbs free energy was in the range of -2.89~-2.14 kJ $mol^{-1}$. The results show that the phenol adsorption is physical, spontaneous and exothermic reaction.

• Journal of Agricultural Extension & Community Development
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• v.16 no.2
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• pp.363-384
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• 2009

This study aimed at finding directions for Korean agriculture to establish a new paradigm of sustainable development. Various problematic issues and concerns in the environment necessitate the transformation of Korea's development paradigm from unconditional growth to "Green Growth" through new policies on green value and review of various advanced researches. In this research, the environment-friendly agriculture's problems, particularly in agribusiness were analyzed. Drawing from Michael Porter's Value Chain Analysis, this research developed a value chain model in agriculture that reflects the environment and the present situations. Future directions in the agriculture sector were also discussed. Korea realized food self-sufficiency through the green revolution in the early 1970s. However, a lot of problems have also occurred, including ground and water pollution and the destruction of ecosystems as a result of the overuse of pesticides and chemical fertilizers. In the late 1970s, the growing interest on environment-friendly agriculture led to the introduction of sustainable methods and techniques. Unfortunately however, these were not innovative enough to foster environment-friendly agriculture. Thereafter, the consumers' distrust on agricultural products has worsened and concerns about health have increased. In view of this, the Ministry of Food, Agriculture, Forestry and Fisheries introduced in December 1993 a system of Quality-Certified Products for organic and pesticide-free agri-foods. Although a fundamental step toward the sustainability of the global environment, this system was not enough to promote environment-friendly agriculture. In 2008, Korea's vision is for "Low Carbon Green Growth" to move forward while also coping with climate change. But primary sectors in a typical value chain do not consider the green value of their operations nor look at production from an environmental perspective. In order to attain sustainable development, there is a need to use less resources and energy than what is presently used in Korean agricultural and value production. The typical value chain should be transformed into a "closed-loop" such that the beginning and the end of the chain are linked together. Such structure allows the flow of materials, products and even wastes among participants in the chain in a sustained cycle. This may result in a zero-waste sustainable production without destroying the ecosystem.

• Korean Journal of Construction Engineering and Management
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• v.15 no.4
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• pp.58-67
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• 2014

The proportion of investment in national R&D projects in construction and transportation has been increasing continuously; in terms of the size of R&D projects, there are many medium- to large-sized projects of over KRW 10 billion. However, in spite of such continuous increase in R&D investments, there are many technologies developed but not commercialized, i.e., the quiescence of technology. Accordingly, it is necessary to link the R&D results to commercialization by expanding the scope of R&D projects. In this context, this study presented objective reference prices to be used in contracting/transacting technology and implementing commercialization strategy by conducting technology valuations against on-going research projects with earnings approach, and by estimating value of patented technology. Sum of free cash flow (business value) that can be generated during the life of the technology was estimated as KRW 512 million by reflecting a discount rate of 16.34% to convert it into the present value. In addition, the technology value was computed as KRW 227million by applying a technology factor of 44.39% to the above value. Based on the technology value estimated in this way, it is necessary to establish industrialization and commercialization strategy of the technology.

• Journal of the Korean Home Economics Association
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• v.20 no.4
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• pp.155-168
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• 1982

What is attempted here is to find out an optimum method for the design of physical environments that could save human energy expenditures and safely perform household duties. There are, if any, very little amount of research done in this area. This is particulary so when the work relates to the designing of household storage facilities in the light of the energy metabolism of human body. The first step to this study, therefore, is to find out the ways by which we can determine the energy metabolism of human body accurately. To measure the volume and the concentration of human respiration continuously and automatically, a new apparatus is selected here. This includes the recording system with the Wright Respirometer and the Expired Gas Analyzer as well as the computer system to multiply volume by concentration of human respiration and to integrate them for a given time. Then, the author experimented on the reliability of this apparatus and came to the conclusion that this apparatus satisfied our need to research the energy metabolism of human body. Next, the general plan and procedures to experiment with this apparatus have been determined as follows: 1) subjects are three young and sound females. Their physical characteristics are shown in Table 1 and most approximates the standard characteristics of Japanese females, 2) height of open shelves is selected in such away as to correspond to the respective height of each subject(see Table 2), 3) utensils to be stored are box shaped object, which weight is 0.5kg, 1.0kg, 2.0kg or 3.0kg, 4) working motions are given while one or two hands as to place utensil on each shelf from the standard working board, 85 cm in height and then to place back it on the board from the shelf and repeated in constant velocity as 10 times per a minute, 5) each posture of motion is chosen by each subject in free, 6) procedures of measurement of human energy metabolism ard shown at(6), 1, Section 3 as specific methods for using this apparatus. Findings of this study are as follows: 1. Human energy expenditures for storing utensils on shelves by each subject are shown in quantity more accurately than in any other studies, under varying conditions about height of shelves, load of utensils and working motion with one hand and two hands (see Fig. 8~13 and Table 3). 2. Experimental formulae of human energy expenditure for that work are shown as formula (8), (9) and (10), to generalize results of 1. and to apply those for working motion under given conditions. 3. As results of analysis on gained data, we are able to show the standard model of human energy expenditures for storing untensils on shelves by the standard Japanese female (see Table 7 and Fig. 14).

• Advances in Energy Research
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• v.1 no.2
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• pp.147-163
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• 2013

The world faces several issues of energy crisis and environmental deterioration due to over-dependence on single source of which is fossil fuel. Though, fuel is needed as ingredients for industrial development and growth of any country, however the fossil fuel which is a major source of energy for this purpose has always been terrifying thus the need for alternative and renewable energy sources. The search for alternative energy sources resulted into the acceptance of a biofuel as a reliable alternative energy source. This work presents the study of optimization of process of transesterification of vegetable oil to biodiesel using NaOH as catalyst. A $2^4$ factorial design method was employed to investigate the influence of ratio of oil to methanol, temperature, NaOH concentration, and transesterification time on the yield of biodiesel from vegetable oil. Low and high levels of the key factors considered were 4:1 and 6:1 mole ratio, 30 and $60^{\circ}C$ temperatures, 0.5 and 1.0 wt% catalyst concentration, and 30 and 60 min reaction time. Results obtained revealed that oil to methanol molar ratio of 6:1, tranesetrification temperature of $60^{\circ}C$, catalyst concentration of 1.0wt % and reaction time of 30 min are the best operating conditions for the optimum yield of biofuel from vegetable oil, with optimum yield of 95.8%. Results obtained on the characterizzation of the produced biodiesel indicate that the specific gravity, cloud point, flash point, sulphur content, viscosity, diesel index, centane number, acid value, free glycerine, total glycerine and total recovery are 0.8899, 4, 13, 0.0087%, 4.83, 25, 54.6. 0.228mgKOH/g, 0.018, 0.23% and 96% respectively. Results also indicate that the qualities of the biodiesel tested for are in conformity with the set standard. A model equation was developed based on the results obtained using a statistical tool. Analysis of variance (ANOVA) of data shows that mole ratio of ground nut oil to methanol and transesterification time have the most pronounced effect on the biodiesel yield with contributions of 55.06% and 9.22% respectively. It can be inferred from the results various conducted that vegetable oil locally produced from groundnut oil can be utilized as a feedstock for biodiesel production.

• The Transactions of the Korea Information Processing Society
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• v.4 no.7
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• pp.1804-1820
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• 1997

In this paper, an efficient call control procedure is presented for next generation wireless ATM networks and its performance is mathematically analyzed using the open queueing network. This procedure is based on a new scheme called as the cell clustering. When we use the cell clustering scheme, at the time that a mobile connection is admitted to the network, a virtual cell is constructed by choosing a group of neighboring base stations to which the call may probabilistically hand over and by assigning to the call a collection of virtual paths between the base stations. Within a microcell/picocell environment, it is seen that the cell clustering can support effectively a very high rate of handovers, provides very high system capacity, and guarantees a high degree of frequency reuse over the same geographical region without requiring the intervention of the network call control processor each time a handover occurs. But since mobiles, once admitted, are free to roam within the virtual cell, overload condition occurs in which the number of calls to be handled by one base station to exceed that cell site's capacity of radio channel. When an overload condition happens, the quality of service is abruptly degraded. We refer to this as the overload state and in order to quantify the degree of degradation we define two metrics, the probability of overload and the normalized average time spent in the overload state. By using the open network queueing model, we derive closed form expressions for the maximum number of calls that can be admitted into the virtual cell such that the two defined metrics are used as the acceptance criteria for call admission control.