• The Korean Journal of Financial Management
• /
• v.25 no.4
• /
• pp.53-78
• /
• 2008

Foreign investors who invest in the Korean stock markets are exposed to two kinds of foreign exchange rate risk, the economic exposure and the translation exposure. The former is the foreign exchange rate exposure in return generating process of the assets invested and the latter is the foreign exchange rate exposure in the translation of domestic return into foreign investors' currency. Domestic investors, however, are exposed only to foreign exchange rate exposure in the asset invested. This different situation on foreign exchange rate exposure between foreign investors and domestic investors can induce different response to exchange rate change by investor groups. Previous studies on foreign exchange rate exposure of Korean firms reported that quite a few Korean firms are exposed to foreign exchange risks and suggested to manage the foreign exchange risks. Also, many studies on the market segmentation showed that a market can be practically segmented according to the characteristics of investor groups. These studies support the hypothesis that the Korean stock market can be practically segmented by the foreign investors' attitude to the foreign exchange rate exposure. This study examines the response of both foreign investors and domestic investors to the foreign exchange rate exposures in Korean stock markets. Test results show that foreign investors increase their sell transactions when the foreign exchange rate exposure of the previous day is negative. This result can be possible when foreign investors attempt to actively manage the decrease in value of their assets due to rising of exchange rate. Analysis on the sell order data is also supportive to this interpretation. Foreign investors also increase their buy transactions when the foreign exchange rate exposure of the previous day is negative. This result can be possible when foreign investors use actively the relation between the increase in asset value and the translation gain due to declining of exchange rate. Analyses on buy order data, however, do not show the same result as the analyses on transaction data. This difference may come from the difference of information contained in transaction data and order data. In summary, the result of the paper supports the hypothesis that foreign investors response differently to foreign exchange rate exposure compared with domestic, Korean investors. Two groups do not show different response when exchange rate exposure is positive, i.e., as foreign exchange rate is increase (decrease), the asset value is increase (decrease). However, foreign investors' response is different from that of domestic investors when exchange rate exposure is negative, i.e., as foreign exchange rate is increase (decrease), the asset value is decrease (increase). These results mean that foreign investors and domestic investors are placed in different situations related to foreign exchange rate exposure, and these differences are reflected in the Korean stock markets. And domestic investors need to consider foreign investors' different attitude to the foreign exchange rate exposure when they analysis foreign investors' trading behavior.

• Journal of Periodontal and Implant Science
• /
• v.35 no.4
• /
• pp.1019-1037
• /
• 2005

The major goals of periodontal therapy are the functional regeneration of periodontal supporting structures already destructed by periodontal disease as well as the reduction of signs and symptoms of progressive periodontal disease. There have been many efforts to develop materials and therapeutic methods to promote periodontal wound healing. There have been increasing interest on the chitosan made by chtin. Chitosan is a derivative of chitin made by deacetylation of side chains. Chitosan has been widely studied as bone substitution and membrane material in periodontology. Many experiments using chitosan in various animal models have proven its beneficial effects. Tetracycline has been considered for use in the treatment of chronic periodontal disease and gingivitis. The aim of this study is to evlauate the osteogenesis of tetracycline blended chitosan membranes on the calvarial critical size defect in Sprague Dawley rats. An 8mm surgical defect was produced with a trephine bur in the area of the midsagittal suture. The rats were divided into five groups: Untreated control group versus four experimental group. Four types of membranes were made and comparative study was been done. Two types of non-woven membranes were made by immersing non-woven chitosan into either the tetracycline solution or chitosan-tetracycline solution. Other two types of sponge membranes were fabricated by immersing chitosan sponge into the tetracycline solution, and subsequent freeze-drying. The animals were sacrificed at 2 and 8 weeks after surgical procedure. The specimens were examined by histologic analyses. The results are as follows: 1. Clinically the use of tetracycline blended chitosan membrane showed great healing capacity. 2. The new bone formations of all the experimental group, non-woven and sponge type membranes were greater than those of control group. But, there was no significant difference between the experimental groups. 3. Resorption of chitosan membranes were not shown in any groups at 2 weeks and 8 weeks. These results suggest that the use of tetracycline blended chitosan membrane on the calvarial defects in rats has significant effect on the regeneration of bone tissue in itself. And it implicate that tetracycline blended chitosan membrane might be useful for guided tissue regeneration.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.8
• /
• pp.1296-1303
• /
• 2014

This study was conducted to develop predictive models for the growth of Bacillus cereus on carrot treated with slightly acidic electrolyzed water (SAcEW) and ultrasonication (US) at different storage temperatures. In addition, the inactivation of B. cereus by US with SAcEW was investigated. US treatment with a frequency of 40 kHz and an acoustic energy density of 400 W/L at $40^{\circ}C$ for 3 min showed the maximum reduction of 2.87 log CFU/g B. cereus on carrot, while combined treatment of US (400 W/L, $40^{\circ}C$, 3 min) with SAcEW reached to 3.1 log CFU/g reduction. Growth data of B. cereus on carrot treated with SAcEW and US at different temperatures (4, 10, 15, 20, 25, 30, and $35^{\circ}C$) were collected and used to develop predictive models. The modified Gompertz model was found to be more suitable to describe the growth data. The specific growth rate (SGR) and lag time (LT) obtained from the modified Gompertz model were employed to establish the secondary models. The newly developed secondary models were validated using the root mean square error, bias factor, and accuracy factor. All results of these factors were in the acceptable range of values. After compared SGR and LT of B. cereus on carrot, the results showed that the growth of B. cereus on carrot treated with SAcEW and US was slower than that of single treatment. This result indicates that shelf life of carrot treated with SAcEW and US could be extended. The developed predictive models might also be used to assess the microbiological risk of B. cereus infection in carrot treated with SAcEW and US.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.30 no.4
• /
• pp.643-653
• /
• 2003

Fibroblast growth factor (FGF) / FGF receptor (FGFR) mediated signaling is required for skeletogenesis in cluding intramembranous and endochondral ossifications Runx2 ($Cbfa1/Pebp2{\alpha}A/AML3$) is an essential transcription factor for osteoblast differentiation and bone formation. Murine calvaria and mandible are concurrently undergoing both intramembranous bone and cartilage formations in the early developmental stage. However the mechanism by which these cartilage formations are regulated remains unclear. To elucidate the effect of FGF signaling on development of cranial sutural cartilage and Meckel's cartilage and to understand the role of Runx2 in these process, we have done both in vivo and in vitro experiments. Alcian blue staining showed that cartilage formation in sagittal suture begins from embryonic stage 16 (E16), Meckel's cartilage formation in mandible from E12. We analyzed by in situ hybridization the characteristics of cartilage cells that type II collagen, not type X collagen, was expressed in sagittal sutural cartilage and Meckel's cartilage. In addition, Runx2 was not expressed in Meckel's cartilage as well as sagittal sutural cartilage, except specific expression pattern only surrounding both cartilages. FGF signaling pathway was further examined in vitro. Beads soaked in FGF2 placed on the sagittal suture and mandible inhibited both sutural and Meckel's cartilage formations. We next examined whether Runx2 gene lies in FGF siganling pathway during regulation of cartilage formation. Beads soaked in FGF2 on sagittal suture induced Runx2 gene expression. These results suggest that FGF signaling inhibits formations of sagittal sutural and Meckel's cartilages, also propose that FGF siganling is involved in the proliferation and differentiation of chondroblasts through regulating the transcription factor Runx2.

• Journal of Aquaculture
• /
• v.16 no.4
• /
• pp.233-239
• /
• 2003

Growth and activities of digestive enzymes in slime flounder (Microstomus achne) larvae were measured from hatching to near the end of larval development (day 58). Larvae reared under starved and fed conditions and the changes of acid phosphatase (ACPase) specific activity, alkaline phosphatase (ALPase) specific activity, trypsin-like enzyme activity and pepsin-like enzyme activity were described with growth and developmental stage of larvae. Total length of the starved larvae was gradually increased for 7 days post hatching and then almost unchanged. Total length of the fed larvae ranged from 5.13$\pm$0.178 mm at the day of hatching to 13.43$\pm$1.395 mm at 58 days after hatching. In starved group, dry body weight decreased from 0.l0$\pm$0.020 mg at the day of hatching to 0.05$\pm$0.012 mg at 12 days after hatching. Dry body weight of fed larvae decreased during the prelarva stage like starved group and then gradually increased. ACPase and ALPase specific activity in the starved larvae increased until all larvae died, however those activities in the fed larvae increased until 20 days and then decreased until 58 days after hatching, with no significant difference between groups. Trypsin-like enzyme activity in the starved larvae was unchanged until 3 days and then was the highest on 5 days after hatching, but not detected after completion of yolksac absorption. Those of fed larvae decreased until 3 days and sharply increased until completion of yolksac absorption. The highest trypsin-like enzyme activity in the fed group was observed at 20 days after hatching. Trypsin-like enzyme activity in the fed larvae was significantly higher than that in the starved larvae from 8 days after hatching. Pepsin-like enzyme activity was increased in 5 days after hatching in both groups. There was significant difference at 8 and 10 days after hatching between both groups. Based on above results, digestive enzyme activities were correspondingly changed to a growth and morphological transformation. Trypsin-like enzyme and pepsin-like enzyme activities are able to be a useful indices for health and growth status in larval slime flounder, because there was significant difference in digestive enzyme activities with developmental stages, growth or feed supply.

• Tuberculosis and Respiratory Diseases
• /
• v.45 no.4
• /
• pp.776-784
• /
• 1998

Background: The cyclin D1 gene is one of the most frequently amplified chromosomal regions(11q13) in human carcinomas. In laryngeal and head and neck carcinomas, its overexpression has been shown to be associated with advanced local invasion and presence of lymph node metastases. Cyclin D1 may therefore playa key role in cell growth regulation and tumorigenesis. Lung cancer is a worldwide problem and in many contries it is the most lethal malignancy. As relapse is frequent after resection of early stage non-small cell lung cancer, there is an urgent need to define prognostic factors. Purpose: This study was undertaken to evaluate the prognostic value of the cyclin D1, that is one the G1 cyclins which control cell cycle progression by allowing G1 to S phase transition, on the patients in radically resected non-small cell lung cancer. Method: Total 81 cases of formalin-fixed paraffin-embedded blocks from resected primary non-small cell lung cancer from January 1, 1983 to July 31, 1995 at Hanyang University Hospital were available for both clinical follow-up and immunohistochemical staining using monoclonal antibodies for cyclin D1. Results : The histologic classification of the tumor was based on WHO criteria, and the specimens included 45 squamous cell carcinomas, 25 adenocarcinomas and 11 large cell carcinomas. Cyclin D1 overexpression was noted in 26 cases of 81 cases tested (30.9%). Cyclin D1 expression was not significantly associated with cell types of the tumor, pathological staging and the size of the tumor. But cyclin D1 overexpression was significantly correlated with positive lymph node metastasis(p=0.035). The mean survival duration was $22.76{\pm}3.50$ months in cyclin D1 positive group and $45.38{\pm}5.64$ months in eyclin D1 negative group. There was a nearly significant difference in overall survival between cyclin D1 positive and negative groups(p=0.0515) in radically resected non-small cell lung cancer. Conclusion: Based on this study, cyelin D1 overexpression appears an important poor prognostic indicator in non-small cell lung cancer and may have diagnostic and prognostic importance in the treatment of resectable non-small cell lung cancer.

• Tuberculosis and Respiratory Diseases
• /
• v.46 no.3
• /
• pp.311-316
• /
• 1999

Background: The drug-resistant tuberculosis has recently decreased in Korea, but it is still one of the major obstacles in the treatment of pulmonary tuberculosis. Unfortunately there are no reliable ways to figure out the drug sensitivity pattern of the M. tuberculosis in the starting point of treatment. At least several months which is critical for the success of treatment have to be passed away before getting the report of drug-sensitivity test. The aim of this study was to find out the clinical and radiological parameters that make it possible to predict the drug-resistant pulmonary tuberculosis and to make a correct decision on the antituberculosis drug regimens. Method: We studied 253 pulmonary TB patients with sputum and/or bronchial washing fluid culture-positive diagnosed at the Chung-Ang University Young-San Hospital in the period of 1989-1994. The differences in the clinical and raiological variables between the drug-sensitive and the drug-resistant tuberculosis patients were evaluated. Results: In 66 out of 253 patients(26.1%), drug resistant tuberculosis to at least one antituberculosis drug were found. Patients with retreatment showed higher resistance rate than those with initial treatment(30/69, 43.5% vs 36/184, 19.5%, p<0.01). Patients with cavitary TB showed higher resistance rate than those with non-cavitary TB(24/54, 44.4% vs 42/199, 21.1%, p<0.05). Among patients with initial treatment, those with far-advanced TB showed a higher drug resistance rate than those with minimal lesion(9/23, 36.9% vs 10/82, 12.5%, p<0.05). Patients with culture positive only in the bronchial washing fluid showed lower resistance rate than those with sputum culture positive(7/63, 11.1 % vs 59/190, 31.1%, p<0.05). Conclusion: Prior treatment history for pulmonary tuberculosis, the presence of cavity & far advanced tuberculosis in the radiologic exam, sputum rather than solely bronchial washing culture positivity would be the related factors to the drug resistance. So in the patients with such characteristics, it is needed to try to find out the drug sensitivity pattern of the infecting tuberculosis organism as soon as possible.

• Tuberculosis and Respiratory Diseases
• /
• v.43 no.6
• /
• pp.925-935
• /
• 1996

Background : In order to elucidate one of the pathogenic mechanisms of ARDS associated with pulmonary surfactant and oxidant injury, acute lung injury was induced by N-nitroso N-methylurethane (NNNMU). In this model, the role of phospholipase $A_2$ ($PLA_2$), surfactant, gamma glutamyl transferase (GGT) and morphology were investigated to delineate one of the pathogenic mechanisms of ARDS by inhibition of $PLA_2$ with high dose of dexamethasone. Method: Acute lung injury was induced in Sprague-Dawley rats by NNNMU which is known to induce acute lung injury in experimental animals. To know the function of the alveolar type II cells, GGT activity in the lung and bronchoalveolar lavage was measured. Surfactant phospholipid was measured also. $PLA_2$ activity was measured to know the role of $PLA_2$ in ARDS. Morphological study was performed to know the effect of $PLA_2$ inhibition on the ultrastructure of the lung by high dose of dexamethasone. Results : Six days after NNNMU treatment (4 mg/kg), conspicuous pulmonary edema was induced and the secretion of pulmonary surfactant was decreased significantly. In the acutely injured rats' lung massive infiltration of leukocytes was observed. At the same time rats given NNNMU had increased $PLA_2$ and GGT activity tremendously. Morphological study revealed bizarre shaped alveolar type II cells and hypertrophied lamellar bodies in the cytoplasm of the alveolar type II cells. But after dexamethasone treatment (20 mg/kg, for six days) in NNNMU-treated rats, these changes were diminished i.e. there were decrease of pulmonary edema and increase of surfactant secretion from alveolar type D cells. Rats given dexamethasone and NNNMU had decreased $PLA_2$ and GGT activity in comparison to NNNMU induced ARDS rats. Conclusion : Inhibition of $PLA_2$ by high dose of dexamethasone decreased pathological findings caused by infiltration of leukocytes and respiratory burst. Based on these experimental results, it is suggested that an activation of $PLA_2$ is the one of the major factors to evoke the acute lung injury in NNNMU-induced ARDS rats.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.10
• /
• pp.1363-1370
• /
• 2006

This study was designed to evaluate the effect of Agaricus blazei $\beta-glucan$ and egg shell calcium complex on bone metabolism in ovariectomized (OVX) rats. Forty Sprague-Dewley female rats, 10 weeks of age $(248{\pm}1.7g)$, were divided into 4 groups and fed on the experimental diets for 6 weeks: sham operated control treated with normal diet containing 0.5% calcium (Sham-C), OVX-control treated with normal diet containing 0.5% calcium (OVX-C), $OVX-\beta-glucan$ group treated with $\beta-glucan$ diet containing 0.5% calcium (OVX-G), and $OVX-\beta-glucan$ egg shell calcium complex treated with $OVX-\beta-glucan$ egg shell calcium complex containing 0.5% calcium (OVX-GE). Bone weight of femur was higher in the OVX-GE group than in the other OVX groups. Bone mineral density of femur was significantly different (p<0.05) among the experimental groups and showed the highest level in the OVX-GE group. Calcium absorption rate and retention were higher in the $\beta-glucan$ supplement groups than in the other groups (p<0.05). Alkaline phosphatase activities and osteocalcin levels of serum showed lower in the $\beta-glucan$ supplement groups than in the OVX-C group. Deoxypyridinoline crosslink values of urine, indicator of bone absorption, showed the lowest in the OVX-GE group. The $\beta-glucan$ supplemented groups had a lower bone resorption ratio than in the OVX-C group. We concluded that bioavailability of calcium is higher in $\beta-glucan$ supplement groups compared to those in OVX rats. From the above results, these findings suggest the possibility of using $\beta-glucan$ egg shell calcium complex as a functional food material related to bone metabolism, even though there is no significant difference between the groups of $\beta-glucan$ and $\beta-glucan-egg$ shell calcium complex supplementation.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.40 no.8
• /
• pp.1157-1163
• /
• 2011

This study was conducted to investigate the cause of microbiological contaminants in aseptic chocolate milk and evaluate the effect of a physicochemical treatment on the growth inhibition of isolated bacterial strains. The bacterium isolated from aseptic chocolate milk was identified as Bacillus lentus and was named B. lentus M1. In the heat and pH treatment, the growth of B. lentus was inhibited at 110$^{\circ}C$ for >15 min and at pH's <5 and >10. An electrolyzed water treatment against B. lentus M1, revealed 5 mm growth past the inhibition zone. The effect of ozone gas on B. lentus M1 growth was evaluated using viable cell counts. When the initial number of B. lentus M1 was $10^2$ and $10^3$ CFU, the bacteria were completely suppressed by ozone gas treatment for 10 and 30 min, respectively. In a microwave treatment, B. lentus M1 was sterilized following microwave treatment for 1 min. As the result of ${\gamma}$-irradiation against B. lentus M1, numbers decreased as the ${\gamma}$-irradiation dosage increased. These results show the growth inhibition effects against contaminants in aseptic chocolate milk using physicochemical treatments.