• Korean Chemical Engineering Research
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• v.46 no.2
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• pp.423-429
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• 2008

Currently, Ash-free clean coal producing process by solvent extraction is under development. The produced ash-free clean coal can be directly combusted in a gas turbine which results in substantial improvement of power generation efficiency. However, the clean coal produced by the solvent extraction still contain trace amount of alkali metal which may cause corrosion on turbine blades during the direct combustion. In present work ${\alpha},{\beta}$-metal (Zr and Ti) phosphates and H-Y zeolite were synthesized and their ion exchange characterizations were investigated for the application on alkali metal removal for clean coal production. $Na^+$ ion removal capacities of the metal phosphates and H-Y zeolite were measured and compared in both aqueous solution (100 ppmw, $Na^+$) and coal dissolved N-methyl-2-pyrrolidone (NMP, 12 ppmw $Na^+$) at elevated temperature. In aqueous solution, the ${\beta}$ form metal phosphates showed very high ion exchange capacities compared to ${\alpha}$ form. ${\beta}$ form metal phosphates also showed higher $Na^+$ removal capacities than H-Y zeolite. In ion exchange medium of NMP, all the ${\alpha}$ form metal phosphates showed over 90% of $Na^+$ ion removal efficiency in the temperature range of 200 to 400 while that of H-Y zeolite decreased as a half when the temperature was over 350. In addition, the regenerated metal phosphates by acid treatment showed no sign of degradation in $Na^+$ removal efficiency. Among the metal phosphates used, $Zr_{0.75}Ti_{0.25}(HPO_4)_2$ showed the best performance in $Na^+$ removal and is expected to be the most suitable inorganic ion exchanger for the alkali metal removal process.

• Journal of Technologic Dentistry
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• v.20 no.1
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• pp.37-49
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• 1998

The specimens used were Ag-25 Pd-15 Cu ternary alloy and Au addition alloy. These alloys were melted and casted by induction electric furnace and centrifugal casting machine in Ar atmosphere. These specimens were solution treated for 2hr at $800^{\circ}C$ and were then quenched into iced water, and aged at $350{\sim}550^{\circ}C$ Age- hardening characteristics of the small Au-containing Ag-Pd-Cu dental alloys were investigated by means of hardness testing. X-ray diffraction and electron microscope observations, electrical resistance, ergy dispersed spectra and electron probe microanalysis. Principal results are as follows : Hardening occured in two stages, i.e., stage I in low temperature and stage II in high temperature regions, during continuous aging. The case of hardening in stage I was due to the formation of the $L1_0$ type face-centered tetragonal PdCu-ordered phase in the grain interior and hardening in stage I was affected by the Cu concentration. In stage II, decomposition of the ${\alpha}$ solid solution to a PdCu ordered phase($L1_0$ type) and an Ag-rich ${\alpha}2$ phase occurred and a discontinuous precipitation occurred at the grain boundary. From the electron microscope study, it was conclued that the cause of age-hardening in this alloy is the precipitation of the PdCu ordered phase, which has AuCu I type face-centered tetragonal structure. Precipetation procedure was ${\alpha}{\to}{\alpha}+{\alpha}_2+PdCu {\to}{\alpha}_1+{\alpha}_2+PdCu$ at Pd/Cu = 1.7 Ag-Pd-Cu alloy is more effective dental alloy as ageing treatment and is suitable to isothermal ageing at $450^{\circ}C$.

• Journal of agricultural medicine and community health
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• v.34 no.1
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• pp.58-66
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• 2009

Objectives: Active participation of poultry breeder in surveillance system of Avian Influenza (AI) is very important. Therefore this study was conducted to present basis data for active report of AI that is affected by media's coverage in poultry breeder. Methods: Subjects were 88 persons, 28 who were poultry breeder at epidemic area of AI and 60 who were general person at non-epidemic area. Data were collected by the trained investigator from Jul. 1 to Aug. 31, 2008. Respondents were interviewed by means of a structured questionnaire. Results: The third-person effect among perceptions of influence in media's report on the AI was higher in breeder (32.1%) than in non-breeder (10.0%). However, Confidence to media report on the AI was lower in breeder than in non-breeder. Intention to report of the AI was 71.4% in breeder respectively, was 90.0% in non-breeder. There was statistically significant lower in breeder than non-breeder. The cause of avoidance of report was 'economic damage' for 87.5%, which acocounted for the majority of cases. Confidence to media report on the AI were positively correlated with concern on the AI and perception on seriousness of the AI, but negatively correlated with the third-person effect. Conclusions: These results showed that intention to report of the AI of breeder was susceptible to influenced by the third person effect and confidence in media's report on the AI. Therefore we should give a special attention to increase active report of poultry breeder during epidemic period of AI which is consideration of reasonable strategy of media's coverage, including mind and emotion state of poultry breeder.

• Journal of Aquaculture
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• v.17 no.2
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• pp.144-150
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• 2004

This experiment was conducted to evaluate the parameters such as nutrient requirements, POY, AnV, Totox, VBN, total plate count, dietary fatty acids and amino acids composition, that are not included in the registered standard composition items required by the Ministry of Agriculture and Forestry, of a moist pellet (MP), three domestic extruded pellets (DEP-1, DEP-2, DEP-3), and two foreign extruded pellets (FEP-1, FEP-2) that are utilized by domestic flounder farms at present. The crude protein was added in excess of the dietary protein requirement in 6 kinds of feeds. When considering the proper PH ratio, it is obvious that protein was added in excess, especially in MP and FEP-2. Crude fat was also added in excess, especially in FEP-1. MP contained a higher dietary phosphorus content than formulated feeds, surpassing the dietary phosphorus requirement and greatly increasing the possibility for causing water pollution. The oxidation of fatty acid and decomposition of protein in MP were higher than in formulated feeds, and may also cause problems on fish farms. Also, it is difficult to store and manage MP, Among the fatty acids, EPA and DHA contents in MP were higher than those in formulated feeds. It is necessary to conduct further studies of EPA and DHA contents in formulated feeds. Lysine content in MP and FEP-2 could meet the dietary lysine requirement of flounder, however, the possibility of insufficient lysine content in the other formulated feeds was high and we considered that extra supplementation was necessary. Therefore, it is necessary to set up quality control standards according to fish species and sizes while considering the specific character of aquatic formulated feeds to restore the confidence of feed companies and aquaculturists to these feeds. This may be an opportunity to make an earlier change from MP to formulated feeds.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.48-55
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• 2002

Objective: Stress is known to be a common cause of short-term insomnia and insomniacs often complain that stress induces sleep problems. However, previous studies on the correlation between stress and sleep do not show consistent results. We aimed to investigate the effects of minor stressful events on sleep among college students. Method: Physically and mentally healthy college student volunteers filled out a self-assessment questionnaire to evaluate their stress and sleep. To find out the status of average stress and sleep, the volunteers filled out K-DSI and daily sleep assessments on three consecutive days. In addition, we surveyed the amount of caffeine beverage intake and assessed the degree of depression and anxiety. Results: The total number of students participating in this study was 202, 101 men and 101 women. Minor stress turned out to significantly affect non-restorative sleep and secondary symptoms of insomnia (awakening difficulty, displeasure, feeling of dissatisfaction with sleep, physical uneasiness or pain at awakening, daytime sleepiness, depressive moods, tiredness and concentration difficulty). However, global PSQI score, self-reported sleeping hours, sleep latency, awakening frequency, frequency and duration of napping, were not explained by stress scores. Conclusion: In this study, minor stresses seemed to affect sleep, especially secondary symptoms caused by non-restorative sleep. We can thus infer that minor stresses impair the restorative effects of sleep by inducing arousal, and the direct relationship the two can be confirmed by polysomnogram.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.3
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• pp.391-399
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• 2004

The purpose of this study was to compare curing efficiency of newly developed curing units to traditional halogen curing unit by measuring thermal change and surface microhardness according to curing light system. Materials and mathods : The types of curing units were traditional low intensity halogen light(Optilux 360), plasma arc light(Flipo), low heat plasma arc light(Aurys), low intensity LED(Starlight), and high intensity LED(Freelight2). Temperature at the tip of light guide was measured by a digital thermometer using K-type thermocouple. And after resin was filled to 2, 3, 4mm teflon mold, bottom temperature measured during curing. After 24 hours, microhardness of top surface and bottom surface of each resin specimen were measured. Results : The result of this study can be summarized as follows, 1. As measuring temperature of curing unit tips, Flipo is the highest as $52.4^{\circ}C,\;Freelight2(37.86^{\circ}C),\;Optilux360(32.68^{\circ}C),\;Aurys(32.34^{\circ}C),\;and\;Starlight(26.14^{\circ}C)$ were followed. 2. Flipo and Freelight2 were the highest similarly and Optilux360 and Aurys were similarly next and Starlight was lowest in temperature of bottom surface of resin mold. 3. Microhardness of top surface were generally similar, and Aurys was relatively low. 4. Optilux 360 and Freelight2 were the highest, and Flipo, Starlight, and Aurys were followed in microhardness of bottom surface. Conclusions : The results suggest that careful use of Flipo and Freelight2 might be able to cure greater depth of resin composite and do not cause thermal problems than other curing units.

• Clinical and Experimental Pediatrics
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• v.49 no.8
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• pp.870-874
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• 2006

Purpose : Popular use of fetal ultrasonography has increased to detect congenital hydronephrosis(CH) which is the most common anomaly prenatally detected. We'd like to determine the frequency and clinical characteristics of prenatally diagnosed CH and outcome of ureteropelvic junction stenosis(UPJS). Methods : The records of births between January 1994 and June 2003 in Chonnam National University Hospital(CNUH), and the records of children who were diagnosed with CH in the Department of Pediatrics of CNUH during the above period, were retrospectively analyzed. In the patients with UPJS, the initial anterior posterior diameters of renal pelvis(APD) were compared between the spontaneous regression (SR) and operation group(OP). In the SR group, sequential regression rates of APD were estimated. Results : Among a total 9,076 births, 231(2.54 percent) patients with 293 renal units were diagnosed as CH and 19(6.78 percent) renal units spontaneously regressed 3 days after birth. In 228 children(56 bilateral; 172 unilateral; total 284 renal units) diagnosed with CH in the department of pediatrics of CNUH, male(71.9 percent) and left kidney(69.2 percent) predilection were found and 78.1 percent of CH were caused by UPJS. The initial APD of the SR group(121 units) in UPJS was $7.8{\pm}6.28mm$, which was significantly smaller than the APD($26.8{\pm}12.14mm$) of the OP group(25 unit)(P<0.05). In the SR group, 81 percent spontaneously regressed within one year. Conclusions : In CH, male and left kidney predilection were found. UPJS was the most common cause of CH and initial APD in UPJS at 3 days of age was a good prognostic indicator. Close monitoring should be done for at least one year because most SR in UPJS regressed spontaneously within one year.

• Clinical and Experimental Pediatrics
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• v.52 no.1
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• pp.75-80
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• 2009

Purpose : In adults, valproate (VPA) has been reported to be associated with thrombocytopenia. However, few studies have investigated this association in children, and the factors affecting platelet counts remain controversial. This study was undertaken to investigate changes in platelet counts following VPA therapy and related factors in children with epilepsy. Methods : Our subjects comprised 75 epileptic children who had received VPA monotherapy for at least 1 year between January 2000 and December 2005. We regularly examined platelet counts at intervals of 6 to 12 months after baseline platelet counts before VPA treatment. We analyzed changes in platelet counts according to several factors such as sex, seizure type, underlying causes of epilepsy, age at the start of medication as well as at the last follow up, duration of VPA administration, VPA dose, serum VPA level, and body weight at the last follow up. Results : Overall, the platelet counts decreased significantly after VPA therapy. The average baseline platelet count was $312.5{\pm}109.1{\times}10^6/mL$. At the last follow up, the average platelet count was $261.7{\pm}72.2{\times}10^6/mL$. We observed the relationship between platelet counts and serum levels of VPA; while children with serum VPA <$75{\mu}g/mL$ showed no change in platelet counts (P=0.102), children with serum VPA >$75{\mu}g/mL$ showed a significant decrease in platelet counts. Conclusion : VPA may cause a significantly decreased platelet count in children with epilepsy. High serum VPA levels were associated with development of thrombocytopenia.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.3 no.2
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• pp.181-187
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• 2000

Purpose: The purpose of our study is to provide useful information for the prevalence of obesity by the standard weight for height and the relationship of the body image to dieting methods for weight control in children. Methods: The survey was performed by an anthropometry and a special questionnaire on children in grades 5 to 6 at elementary schools from May to June 1997 in Kwangju city. Results: 1) Selected individuals were categorized into obese, normal, thin by the standard weight for height and body image. The prevalence of obesity by the standard weight for height was 19.5%, normal was 70.5%, thin was 10.1% in males and respectively 10.5%, 66.3%, 23.1% in females. The prevalence of obesity in regards to body image was 18.4%, normal was 58.4%, thin was 23.2% in males and respectively 24.5%, 58.6%, 16.9% in females. 2) The obese body image was 6.8% in normal and thin groups in males and 19.4% in females. The body image of obese children who do not perceive themselves as obese was 32.6% in males and 28.7% in females. 3) The standard body image was 88.8% as realized by themselves, 77.9% when they compared themselves to friends, 62.7% as told by parents, 56.8% as told by friends, and 29.9% when they compared themselves to celebrities. 4) The source of information for dieting treatment was 44% from radio and television, 30% from books, newspapers, magazines, 17% from family and 9% from friends and seniors. 5) The prevalence of dieting according to the standard weight for height was 18.0% in thin, 18.7% in normal and 36.7% in obese group in males and respectively 17.8%, 22.4%, 46.3% in females. There was a statistically significant correlation between males and females (p<0.0005). 6) The prevalence of dieting up to 2 weeks in the thin and normal groups as recognized by weight centile was 17.3% according to body image. The prevalence of dieting up to 2 weeks in the obese groups was 37.2% according to body image (p<0.001). Conclusion: We suggest that many students perceived their body size incorrectly and tried weight control. The incorrect perception of body size seems to cause the problem of failure to thrive, malnutrition etc. It is necessary for further study to find and prevent side effects by unnecessary weight control and to provide proper health education and management about obesity.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.10 no.2
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• pp.129-137
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• 2007

Purpose: It has been reported that children with chronic pain have higher levels of anxiety than age-matched controls. Therefore, this study was designed to determine the relationship between anxiety and recurrent abdominal pain in elementary school children. Methods: In 2005, we surveyed 1,254 elementary school children (592 boys and 662 girls) whose ages ranged from 7 to 12 years. The degree of trait and state anxiety was compared between agroup suffering from intermittent abdominal pain, a group suffering from recurrent abdominal pain and a normal control group following the Korean version of Spielberger's State-Trait Anxiety Inventory YZ form (STAI-YZ). Results: 709 (56.5%) and 69 (5.5%) of the patients reported intermittent abdominal pain and and recurrent abdominal pain, respectively, during the 12 month period before this study was conducted, and trait and state anxiety values for each of these groups was 116 (9.3%) and 63 (5.0%), respectively. In addition, the State-Trait Anxiety score was significantly higher in the group with intermittent abdominal pain and RAP than the anxiety score of the normal control group. Additionally, the STAI-YZ score increased in proportion to the severity of abdominal pain, but was not correlated with the duration, frequency, onset time or location of abdominal pain. Furthermore, the proportion of the group with abdominal pain in the group that had trait or state anxiety was significantly higher than the proportion of the group that did not have trait and state anxiety. Conclusion: Recurrent abdominal pain during childhood is correlated with state and trait anxiety, therefore, psychological factors, such as anxiety duringtreatment, must also be considered when determining the cause of recurrent abdominal pain.