• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.301-306
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• 2014

A porous silicon microcavity (PSMC) sensor has been made for vapors of solvent solutions, and a method has been developed in order to obtain simultaneous determination of two volatile substances with different concentrations. In our work, the temperature of the solution and the velocity of the air stream flowing through the solution have been used to control the response of the sensor for ethanol and acetone solutions. We study the dependence of the cavity-resonant wavelength shift on solvent concentration, velocity of the airflow and solution temperature. The wavelength shift depends linearly on concentration and increases with solution temperature and velocity of the airflow. The dependence of the wavelength shift on the solution temperature in the measurement contains properties of the temperature dependence of the solvent vapor pressure, which characterizes each solvent. As a result, the dependence of the wavelength shift on the solution temperature discriminates between solutions of ethanol and acetone with different concentrations. This suggests a possibility for the simultaneous determination of the volatile substances and their concentrations.

• Korean Journal of Food Science and Technology
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• v.44 no.3
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• pp.287-292
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• 2012

Light effects on temperature dependence of safflower oil oxidation and tocopherol degradation were studied. Safflower oil was oxidized at 20, 40, 60, or $80^{\circ}C$ for 30, 30, 15, and 6 days, respectively, in the dark or under light. Oil oxidation was evaluated with peroxide value (POV) and conjugated dienoic acid (CDA) value, and tocopherols were monitored by HPLC. Safflower oil consisted of palmitic, stearic, oleic, and linoleic acids at 7.3, 2.0, 14.2, and 76.6%, respectively, with tocopherols at 1157.1 mg/kg. Peroxide and CDA values of safflower oil increased while tocopherol contents decreased with the oxidation time and temperature. Light increased and accelerated the oil oxidation and tocopherol degradation. Temperature dependence of the oil oxidation and tocopherol degradation was higher in the dark rather than under light. The results suggest that temperature control could be more essential in the dark rather than under light with regard to the oxidative stability of safflower oil.

• Journal of Information Technology Services
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• v.7 no.1
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• pp.167-193
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• 2008

Clients' outsourcing strategies noted in the IT outsourcing literature generate varying levels of client dependence on vendors. This study investigates clients' efforts to mitigate such dependence by utilizing multiple vendors. We use the theoretical lenses of resource dependency and opportunism to study this phenomenon. Specifically. we consider degree of outsourcing, duration of contract, and externalization of control as strategic choices that engender vulnerabilities that clients seek to offset by using multiple vendors. This study then considers the basis of the outsourcing relationships, clients' satisfaction with the relationships. and clients' IT workforce size as conditions that induce clients' concerns about vendor opportunism. This study argues that these conditions can exacerbate clients' experience of vulnerability. further encouraging clients' use of multiple vendors. The research model developed is tested in a survey of firms in South Korea. Results suggest a strong impact of outsourcing strategic choices on the number of vendors used by clients. The anticipated moderating effects of opportunism were only weakly supported by the data though. Theoretical and practical implications of the results are considered and suggestions for future research are offered.

• Journal of applied mathematics & informatics
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• v.24 no.1_2
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• pp.49-64
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• 2007

In this paper, we investigate optimal policies for three age-dependent populations in a competition system, which is controlled by fertility. By using Dubovitskii-Milyutin's general theory, the maximum principles are obtained for problems with free terminal states, infinite horizon and target sets, respectively.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.8
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• pp.849-853
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• 2014

In micro-scale electromechanical systems, the power to perform accurate position sensing often greatly exceeds the power needed to generate motion. This paper explores the implications of sampling rate and amplifier noise density selection on the performance of a system identification algorithm using a capacitive sensing circuit. Specific performance objectives are to minimize or limit convergence rate and power consumption to identify the dynamics of a rotary micro-stage. A rearrangement of the conventional recursive least-squares identification algorithm is performed to make operating cost an explicit function of sensor design parameters. It is observed that there is a strong dependence of convergence rate and error on the sampling rate, while energy dependence is driven by error that may be tolerated in the final identified parameters.

• International journal of advanced smart convergence
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• v.7 no.2
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• pp.38-46
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• 2018

This study proceeded an experiment that can increase such physiological properties of heated radish extract. During the extraction of radish, including the byproduct, an increase in antioxidant properties of radish according the heating temperature was performed. Upon the extracts of radish bark and radish green extract(mucheong), the physiological functionalities and antioxidant activity were investigated. As a result, the color of radish ethanol extract in dependence of heating temperature, showed light brown color at low heating temperature and black color from $150^{\circ}C$. The total polyphenol content significantly increased as a result of heat treatment; 6.7 times and 22 times higher than the control at $110^{\circ}C$ and $150^{\circ}C$, respectively. DPPH radical scavenging ability and antioxidant property increased with increasing heating temperature; in comparison to heat-treated radish at $110^{\circ}C$ and $150^{\circ}C$, $IC_{50}$ decreased by 1/22 times. $IC_{50}$ of the control was 23times higher than $150^{\circ}C$ heat treated radish (Control $IC_{50}$:130.305). According to the graph that represents ABTS activity, antioxidant activity increased in dependence of heat treatment likewise to the total polyphenol content and DDPH radical scavenging activity. Upon heat treatment at $150^{\circ}C$, antioxidant activity in consequence of ABTS assay increased 23 times higher than the control.

• Journal of East-West Nursing Research
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• v.19 no.2
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• pp.177-185
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• 2013

Purpose: This study was to identify the relations between stress and health locus of control in nursing college students. Methods: A total of 243 subjects aged between 17 and 27 were selected through convenient sampling. Data were collected with a self reported questionnaire from March 2 to 25, 2013. Collected data were analyzed with SPSS/PC Win 15.0. Results: Differences in stress and health locus of control according to general characteristics were as follows. Stress were significantly different according to gender (t=-2.51, p<.05), grade (F=5.40, p<.01), school record (F=5.72, p<.01), stress solving methods (F=2.62, p<.05). Internal health locus of control was significantly different according to gender (t=2.30, p<.05), grade (F=14.73, p<.001), religion (F=4.63, p<.01), school record (F=5.29, p<.01), economic state (F=5.50, p<.001) and smoking (F=4.17, p<.05). Chance health locus of control was significantly different according to sibling rank (F=2.86, p<.05). Except chance health locus of control, internal heath locus of control and dependence health locus of control have a negative correlation with stress. 15.6% of variance in stress was explained by dependence health locus of control, chance health locus of control, and grade. Conclusion: The findings of this study may be useful in understanding the stress expression of nursing college students and developing more specific programs on personality and self-control.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.12
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• pp.7248-7258
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• 2014

The study was conducted as a quasi-experimental study targeting 60 patients with ischemic heart disease to determine how the smoking cessation program that uses telephone counseling and text messaging (short message) affects smoking cessation self-efficacy, nicotine dependence, co levels, and smoking cessation rate of the first, second experimental group at varying times of arbitration and control group. An examination of the effects of this program revealed the control group to have a significant increase in smoking cessation self-efficacy, smoking cessation rate than the first and second group but a significant decrease in the nicotine dependence, co levels. In addition, although the control group showed a significant increase in smoking cessation self efficacy, smoking cessation rate and a significant decrease in co levels than other groups, there was no difference in nicotine dependence. Therefore, a smoking cessation program that uses telephone counseling and text messaging (short message) for patients with ischemic heart disease worked for the smoking cessation rate and appeared to be more effective, depending on the times of arbitration.

• Journal of The Korean Association For Science Education
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• v.28 no.6
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• pp.675-684
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• 2008

This study investigated the effects of the prescribed instructional strategy for reducing students' connecting errors in learning chemistry concepts with multiple external representations by students' field independence-dependence. Seventh graders (N=126) at a coed middle school were assigned to control and treatment groups. The students learned "Boyle's Law" and "Charles's Law" for two class periods. Results revealed that the students in the treatment group scored significantly higher than those in the control group in a conception test. The scores of the treatment group were significantly higher than those of the control group in a motivational learning test, especially in 'attention' of the test. However, there was no significant interaction between the instruction and students' field independence-dependence in the two tests. Most students in the treatment group perceived the instruction positively in cognitive and motivational aspects.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.8 s.113
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• pp.864-871
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• 2006

In the development of electricity generating wind turbines for wind farm application, only two types have survived as the methods of power regulation; stall regulation and full span pitch control. The main purpose of this paper is to experimentally identify the characteristics of noise emission of wind turbines according to the power regulation types. The sound measurement procedures of IEC 61400-11 are applied to field test and evaluation of noise emission from each of 1.5 MW and 660 kW wind turbines (WT) utilizing the stall regulation and the pitch control for the power regulation, respectively. Apparent sound power level, wind speed dependence, third-octave band levels and tonality are evaluated for both of WTs. It is observed that equivalent continuous sound pressure levels (ECSPL) of the stall control type of WT continue to increase with increasing wind speed whereas those of the pitch control type of WT show less correlation with wind speed. These observed characteristics are believed to be due to the different airflow patterns around the blade between the stall regulation and the pitch control types of WT; the airflow on the suction side of blade in the stall types of WT are separated at the high wind speed. It is also found that the 1.5 MW WT using the stall control emits lower sound power than 660 kW one using the pitch control at wind speeds below 8m/s, whereas sound power of the former becomes higher than that of the latter in the wind speed over 8m/s. This wind-speed dependence of sound power leads to the very different noise omission characteristics of WTs depending on the seasons because the average wind speed in summer is lower than 8m/s whereas that in summer is higher. Based on these experimental observations, it is proposed that, in view of environmental noise regulation, the developer of wind farm should give enough considerations to the choice of power regulation of their WTG based on the weather conditions of potential wind farm locations.