• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.863-870
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• 2016

We investigated the physical/chemical phenomena that a slow loss of $CO_2$ inventory into sodium after the sodium-$CO_2$ boundary failure in printed circuit heat exchangers (PCHEs), which is considered for the supercritical $CO_2$ Brayton cycle power conversion system of a sodium-cooled fast reactor (SFR). The first phenomenon is plugging inside narrow sodium channels by micro cracks and the other one is damage propagation referred to as wastage combined with the corrosion/erosion effect. Experimental results of plugging shows that sodium flow immediately stopped as $CO_2$ was injected through the nozzle at $300{\sim}400^{\circ}C$ in 3 mmID sodium channels, whereas sodium flow stopped about 60 min after $CO_2$ injection in 5 mmID sodium channels. These results imply that if pressure boundary of sodium-$CO_2$ fails a narrow sodium channel would be plugged by reaction products in a short time whereas a relatively wider sodium channel would be plugged with higher concentration of reaction products. Wastage by the erosion effect of $CO_2$ (200~250 bar) hardly occurred regardless of the kinds of materials (stainless steel 316, Inconel 600, and 9Cr-1Mo steel), temperature ($400{\sim}500^{\circ}C$), or the diameter of the $CO_2$ nozzle (0.2~0.8 mm). Velocities at the $CO_2$ nozzle were specified as Mach 0.4~0.7. Our experimental results are expected to be used for determining the design parameters of PCHEs for their safeties.

• International Commerce and Information Review
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• v.4 no.2
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• pp.253-277
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• 2002

Nowaday, the advanced technology in information and communication has been leading the dramatic change of transaction paradigm expansion from physical basis to electronic one. As we know, financial services support most of financial exchange between two business parties. So the expansion of electronic transaction paradigm affects to every financial institutions which provide financial services. Thus, financial institutions have accepted e-Finance systems and providing internet financial services to live in the competition. The purpose of this study is to contribute the qualitative enhancement of its customer service, rapid diffusion and accurate strategy establishment for e-Finance industry in the user side. Through the literature review and factor and reliability analysis, this study selects six diffusion factors such as efficiency of perceived e-Finance, reliability and safety of e-Finance in perceived e-Finance itself's characteristic; confidence, technical factors and the customer service quality of e-Finance system in perception on e-Finance System; inclination to innovation in the personal characteristic. According to result of hypothesis verification by using logistics regression analysis, technical factors and the customer service quality of e-Finance system in perception on e-Finance System and inclination to innovation in the personal characteristic gave statistically positive effect to the diffusion decision at the significant level 0.05 and 0.01. However efficiency of perceived e-Finance, reliability and safety of e-Finance in perceived e-Finance itself's characteristic didn't affect to diffusion decision and confidence of e-Finance system in perception on e-Finance System didn't have any statistical significancy. This study can be used as a basic material for the forward empirical study of diffusion factors in the user side and be able to apply to company and government policy making or embodiment, determination for customer service quality degree of financial institutions. But this study has some limitations like didn't touch satisfaction factors and its effect, only deal domestic customers and didn't use multi-regression analysis.

• Journal of Korean Academy of Nursing Administration
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• v.5 no.1
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• pp.149-167
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• 1999

This study was designed and carried out to investigate the effect of Assertiveness Training on the stress response and assertive behavior of emergency room nurses from September 22, to December 21. 1997. The subjects were 45 emergency room nurses of three general hospitals of Korea University Medical Center; 25 assigned for the experimental and 20 for the control group. The Assertive Training Program was composed of cognitive training, behavioral training and progressive muscle relaxation. The subjects of the experimental group carried out the 15-minute progressive muscle relaxation according to recorded-tape once a day for 6 weeks. The cognitive and the behavioural training were conducted by the investigator for 5-8 subjects at a time for 9 series, at an interval of 4-5 days. Post-measurement were administered to all sujects in two groups three weeks after the last session. The level of general stress (Cline, 1992), job stress (Kim & Koo, 1984), physiological response to stress (cortisol, epinephrine, norepinephrine), symptoms of stress (Lee, 1984) and assertive behavior (Kim, 1982) were measured before the first and after the last experiments. Data were analysed by x2, t, paired t, Wilcoxon signed rank tests Wilcoxon rank sums tests. The results are as follows : 1. The level of general stress of the experimental group was lower than that of the control group, however, no significant difference between the two groups (P=0.234) was revealed. 2. A significant reduction of job stress was revealed in the experimental group (P=0.017). 1) A significant reduction of interpersonal conflicts in the experimental group was revealed (P=0.018). 3. The physiological stress-response were analyzed as follows : 1) A decrease of Cortisol in both the experimental and the control groups was noticed, however, the difference between the two groups was not statistically significant (P=0.991). Pre-and post-measurement of the level of Corti sol revealed that a notable decrease in the experimental group and an increase in the control group with no significant difference in the day-day subjects (P=0.765), a significant decrease was noted on the level of Cortisol of the experimental group in the night-night nurses (P=0.036). 2) An increase of Epinephrine in both groups was noticed, however, a difference was not statistically significant between the two groups (P=0.082). Pre-and post-measurement of the level of Epinephrine revealed that a notable decrease in the experimental group and an increase in the control group with no significant difference in the day-day subjects (P=0.136). increases were noted on the level of Epinephrinel of both groups in the night-night nurses (P=0.136), 3) The level of Norepinephrine of the experimental group was significantly decreased (P=0.020). Pre-and post-measurement of the level of Norepinephrine revealed that a notable decrease in the experimental group and an increase in the control group with no significant difference in the day-day subjects (P=0.073). a significant decrease was noted on the level of Norepinephrine of the experimental group in the night-night nurses (P=0.036), 4. Symptoms of stress were reduced in both groups, with no significant differences between the groups (P=0.127). 1) The physical stress symptoms were reduced in both groups, with no significant difference (P=0.386), 2) The cognitive-behavioral stress symptoms were significantly reduced in the experimental group (P=0.037). 3) The emotional stress symptoms were reduced in both groups with no significant difference between the groups (P=0.110). 5. The assertive behavior was significantly increased in the experimental group (P=0.000). This study signified the Assertiveness Training as an effective mean of self intervention for the reduction of stress of nurses assigned to emergency rooms.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.41-47
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• 2002

Objectives: In a number of simulated night shift studies, timed exposure to bright light improves sleep quality and work performance. We evaluated the effect of bright light on adaptation to night shift work with a field study. Methods: Five female nurses working shifts at Korea University Hospital were recruited for participation in this study. We investigated two series of six consecutive shift rotations comprising three day and three night shifts, using wrist Actigraphy, the Stanford Sleepiness Scale, Visual-analogue scales, STIM and tympanic membrane temperature for daytime sleep quality, alertness, subjective feeling, attention performance, and temperature rhythm. The subjects were exposed to bright light (2,500 lux) from 24:00 to 04:00 a.m. on three consecutive night shifts during the second series, whereas they worked under normal lightening (650 lux) conditions during the first series. Results: Actigraphic assessment of daytime sleep showed no significant difference between the first and third night shift in both baseline and light exposure phase. The mean lowest temperature shifted earlier during baseline phase but not during the light exposure phase. Also, the score for subjective feelings of depression, anxiety, physical discomfort and sleepiness was significantly higher in the third night shift than the first during baseline phase but not during the light exposure phase. Attention and attention switching ability was significantly improved in the third night shift compared to the first night during the light exposure phase but there were no significant changes during the baseline phase. Conclusion: This result suggests that there were no significant differences between the two phases in measures of quality of daytime sleep, but subjective feelings, attention and alertness were enhanced during light exposure. Although some placebo effects and learning effects might influence this result, bright light exposure between midnight and 4:00 a.m. may improve adaptation to night shift. In future, further controlled studies with a larger sample size, including melatonin measurement, are needed for real shift workers.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.401-412
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• 2016

It is extremely difficult to apply conventional grouting methods to subsea tunnelling construction in the high water pressure condition. In such a condition, the rapid artificial freezing method can be an alternative to grouting to form a watertight zone around freezing pipes. For a proper design of the artificial freezing method, the influence of salinity on the freezing process has to be considered. However, there are few domestic tunnel construction that adopted the artificial freezing method, and influential factors on the freezing of the soil are not clearly identified. In this paper, a series of laboratory experiments were performed to identify the physical characteristics of frozen soil. Thermal conductivity of the frozen and unfrozen soil samples was measured through the thermal sensor adopting transient hot-wire method. Moreover, a lab-scale freezing chamber was devised to simulate freezing process of silica sand with consideration of the salinity of pore-water. The temperature in the silica sand sample was measured during the freezing process to evaluate the effect of pore-water salinity on the frozen rate that is one of the key parameters in designing the artificial freezing method in subsea tunnelling. In case of unfrozen soil, the soil samples saturated with fresh water (salinity of 0%) and brine water (salinity of 3.5%) showed a similar value of thermal conductivity. However, the frozen soil sample saturated with brine water led to the thermal conductivity notably higher than that of fresh water, which corresponds to the fact that the freezing rate of brine water was greater than that of fresh water in the freezing chamber test.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.35 no.4
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• pp.301-307
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• 2009

In the previous study, we evaluated and reported about the anti-oxidative activities of extract/fraction of Castanea crenata leaf. Extract/fraction of Castanea crenata leaf showed excellent free radical scavenging activity, cell protective activity and inhibitory activity on tyrosinase and elastase. In this study, in order to investigate the stability of cream containing 0.2 % Castanea crenata ethyl acetate fraction. pH, viscosity, and absorbance were measured under 4 different temperature ($4^{\circ}C$, $20^{\circ}C$, $37^{\circ}C$, $45^{\circ}C)$ and under the sun light at 2 weeks intervals for the 8 weeks. The variations on pH and viscosity of all experimental creams were similar to control cream. The absorbance variation of extract from experimental cream at 353 nm was in the order: under the sun > $45^{\circ}C$ > $37^{\circ}C$ > $20^{\circ}C$ > $4^{\circ}C$. It shows that ethyl acetate fraction in the cream can be oxidized under the sun. The bad smell and discoloration were not shown. Also, physical changes as creaming and cohesion were not shown. Also, transepidermal water loss (TEWL) and water contents in skin were measured. The cream containing Castanea cranata leaf extract was applied to the right lower arm. After 120 min, TEWL of parts was decreased as 29.7 % (experimental cream) and 5.4 % (control cream) respectively. And the water contents in skin were increased 22.6 % (experimental cream) and 24.7 % (control cream) respectively. It was confirmed that a cream containing ethyl acetate fraction of Castanea crenata leaf shows the superior moisturizing effect. The results showed that Castanea crenata leaf extract could be used as a new active ingredient for anti-aging cosmeceuticals.

• Science of Emotion and Sensibility
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• v.13 no.1
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• pp.187-196
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• 2010

Recently, people have been suffering from stress-related fatigue and psychological disorders. Most people depend on medicine for pain relief; many treat pain also through alternative medicine or replacement therapy. However, drug therapy has many side effects, including increased stress after the therapy. In comparison, alternative therapies such as massage and foot reflexology are less damaging to the body, and such therapies can be provided without physical or psychological discomfort. In this regard, the author had previously co-developed color foot reflexology, which combines the merits of color therapy and foot reflexology; color foot reflexology has been shown to have beneficial effects without undue pain. This study investigates the effects of color foot reflexology on the physiological response of the body by comparing the body’s response to the signal with that to the placebo. Healthy adult subjects were selected for the experiment, which was conducted under optimal experimental conditions and design. The results indicated that when stimulated, parasympathetic nerves increased in HRV and that blood pressure, pulse, body heat, peripheral blood flow were dramatically activated. However, the results for the placebo indicated minimal changes or irregular outcomes. The results provide strong evidence for the beneficial effects of the color foot reflexology instrument on the autonomic nervous system and on the physiological response of the body. Future research is warranted to verify the results of the current study by examining patients suffering from diseases and disorders arising from irregular physiological functions in the context of the foot.

• Childhood Kidney Diseases
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• v.3 no.1
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• pp.48-56
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• 1999

Purpose : This multicenter collaboratory study was conducted to see the therapeutic efficacy and side effect of cyclosporine A (Cipol-$N^{(R)}$, Chong Kun Dang) on children with idiopathic nephrotic syndrome who experienced frequently relapsing (FR), steroid dependent (SD), or steroid resistant (SR) pattern. Patients and methods : Thirty-nine children with SD/FR NS and 3 children with SR NS were enrolled in the study. After induction of remission (SD/FR NS) with steroid or after 4 weeks of steroid therapy (SR NS), cyclosporine A was started in a dose of 4-5 mg/Kg/day in two divided dose and steroid (prednisolone or equivalent dose of deflazacort) was tapered slowly. During 16 weeks of study period, monthly check up of physical examination and various laboratory tests including BUN, creatinine, Ccr and cyclosporine blood level were done. Results : Out of 39 children with SD/FR NS, 35($89.7\%$) maintained sustained remission and at 4 weeks after therapy, values of serum protein, albumin, cholesterol, and 24 hours urinary protein excretion showed normal values. Two out of 3 children with SR NS showed and sustained remission with cyclosporine A therapy. Side reaction to cyclosporine A therapy showed hypertrichosis in 8 cases and hyperuricemia in 5 cases. However, other laboratory tests including CBC, liver profile, BUN, creatinine and GFR (creatinine clearance utilizing 24 hour urine) did not show any abnormalities during the 16 weeks of study period. Conclusion : Cyclosporine A (Cipoi-$N^{(R)}$ Chong Kun Dang) can be utilized quite effectively on children with SD/FR or SR NS and further trial of cyclosporine A on long-term basis (1-2 year period) is needed to determine it's efficacy and side effect (especially nephrotoxicity) of long-term administration of cyclosporine A.

• Radiation Oncology Journal
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• v.20 no.2
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• pp.186-192
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• 2002

Purpose : Measurement of transmission dose is useful for in vivo dosimetry. In this study, previous algorithm for estimation of transmission dose was modified for use in cases with tissue deficit. Materials and Methods : The beam data was measured with flat solid phantom in various conditions of tissue deficit. New algorithm for correction of transmission dose for tissue deficit was developed by physical reasoning. The algorithm was tested in experimental settings with irregular contours mimicking breast cancer patients using multiple sheets of solid phantoms. Results : The correction algorithm for tissue deficit could accurately reflect the effect of tissue deficit with errors within ${\pm}1.0\%$ in most situations and within ${\pm}3.0\%$ in experimental settings with irregular contours mimicking breast cancer treatment set-up. Conclusion : Developed algorithm could accurately reflect the effect of tissue deficit and irregularly shaped body contour on transmission dosimetry.

• Food Science of Animal Resources
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• v.27 no.3
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• pp.320-328
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• 2007

This study was conducted to determine the effect of pH adjustment and the addition of cryoprotectants on the quality characteristics of chicken breast surimi. We prepared surimi from Alaska pollack, as a the control, by two time washing times and the addition of cryoprotectants. Different preparations of surimi were manufactured by adjusting to pH 11.0 and the addition of different addition cryoprotectants during frozen storage (T1 : 5% sorbitol and 0.3% polyphosphate, T2: 4% sugar, 5% sorbitol and 0.3% polyphosphate, and T3: 2% salt, 4% sugar, 5% sorbitol and 0.3% polyphosphate). The moisture content was significantly lower in the control and T3 samples. The crude protein content was increased with storage times. The crude protein was higher in the control. The water-holding capacity, myofibrillar protein and shear force were significantly higher in T3 than other surimi samples. All gel characteristics were significantly higher in the control and T3 than other surimi samples. pH 11.0 adjusted chicken breast surimi had greater lightness than the control, and T3 samples had the highest lightness and whiteness. Sensory evaluations were significantly higher in the control and T3 than the other samples. The gel, and physical characteristics and sensory evaluation of T3 were similar to the control. T3 samples had superior color and pH than the control Alaska pollack surimi.