• Journal of Chest Surgery
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• v.30 no.2
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• pp.137-145
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• 1997

From July 1983 to December 1993, total 112 consecutive mitral valve replacements in 107 patients were performed in patient with mitral valvular abnormalities. To estimate the risk factor related to operative death, all patient's perioperative data were reviewed retrospectively. Except 20 patients received concomitant aortic valve replacement and 2 patients had incomplete data, 85 patients were included in this study. Mean age were $37.3\pm$ 13.1 years ranging from 13 to 72 years. Thirty-seven patients were male and fourty-eight patients were female. Mean follow-up durations were $51.1\pm33.8$ months ranging from 6 months t 11 years. Patients in this study showed improvement in mean NYHA functional clssification, from $3.02\pm0.73$ to 1 $78\pm0.55,$ and also in cardiothoracic ratio, from 0.61 $\pm0.09$ to $0.58\pm0.08$ at 6 months follow-up after operation. Operative complications were detected in 23 patients(27.1 %) and common postoperative complications were rhythm disturbance in 7 cases, pulmonary complications in 6 cases and low cardiac output syndrome in 6 cases. Early mortality was 10.6%(n=9) and the most common cause of death was a congestive heart failure due to low cardiac output syndrome. Main cause of our higher operative mortality than other study was that operative mortality in the initial period of our mitral surgery was high(5 operative deaths among 19 mitral valve replacement from July 1983 to December 1985). Actuarial survival was 80.8% at 5 years, 71.8% at 11 years including operative deaths. Actuarial freedom from anticoagulant-related bleeding was 85.3% at 5 years, 78.3% at 11 years. 95.1% at 5 years and 88.8% at 11 years among the patient in this study were free from thromboembolism, and 97.5% at 5 years and 75.1% at 11 years were free from reoperation. Preoperative cardiothoracic ratio and patient's age were statistically significant operative risk factors.

• Korean Journal of Environmental Biology
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• v.17 no.4
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• pp.427-438
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• 1999

Differential growth of Ulva pertusa Kjellman was observed in response to different photon irradiances and seawater. Growth rate of U. pertusa cultivated in the seawater collected from the East Sea was significantly higher than that in the seawater collected from the Yellow Sea. Optimal growth was found at $100{\mu} molm^{-2} s^{-1}$ in both cases. Chlorophyll contents of U. pertusa grown in the east sea water were higher than that cultivated in the west sea water at irradiances lower than $60{\mu} molm^{-2} s^{-1}$. At irradiances higher than $100{\mu} molm^{-2} s^{-1}$, there was no difference in chlorophyll content in between the two different sea waters with tendency that pigmentation decreased with increasing photon irradiances. Nitrate concentration in the west sea water was 2-fold higher than that in the east sea water, while phosphorus concentrations (0.03 ppm) were similar. Concentrations of $Cu^{2+}$ and $Pb^{2+}$ were 0.004 and 0.003 ppm respectively which are far below environmental standard concentrations (0.02 ppm for $Cu^{2+}$ and 0.1 ppm for $Pb^{2+}$). Taking those data into account, we have done laboratory investigations into the effects of inorganic nutrients and heavy metals on U. pertusa. As nitrate concentration increased from 0.5 to 5 ppm, growth rate of U. pertusa increased, but different concentrations of phosphorus did not cause any differential effect. On the other hand, chlorophyll contents increased with increasing phosphorus concentrations. Copper of U. pertusa be toxic decreased the growth and pigmentation as the concentration increased, whereas lead showed no such effect. Concentrations of $Cu^{2+}$ employed in the present study were much higher than those in ambient seawater. Intermittent soaring of $Cu^{2+}$ level as observed in natural seawater could, however, seriously damage the growth behaviour of U. pertusa.

• Development and Reproduction
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• v.12 no.1
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• pp.19-30
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• 2008

Proper development of fertilized oocyte to blastocyst is a key step in mammalian development to implantation. During development of preimplantation embryos, the mammalian embryo needs supply the energy substrate for keep viability. Usually mammalian oocyte get substrate especially energy substrate from oviduct and uterus, because it does not store much substrate into cytoplasm during oogenesis. Carbohydrates are known as a main energy substrate for preimplantation stage embryos. Glucose, lactate and pyruvate are essential component in preimplantation embryo culture media and there are stage specific preferences to them. Glucose transporter and $H^+$-monocarboxylate cotransporter are a main mediator for carbohydrate transport and those expression levels are primarily under the control of intrinsic or extrinsic factors like insulin and glucose. Other organic substances, amino acids, lipids and nucleotides are used as energy substance and cellular regulation factor. Though since 1960s, successful development of fertilized embryo to blastocyst has been accomplished with chemically defined medium for example BWW and give rise to normal offspring in mammals, the role of metabolites and the regulation of intermediary metabolism are still poorly understood. Glucose may permit expression of metabolic enzymes and transporters in compacting morula, capable of generating the energy required for blastocyst formation. In addition, it has been suggested that the cytokines can modulate the metabolic rate of carbohydrate in embryos and regulate the preimplantation embryonic development through control the metabolic rate. Recently we showed that lactate can be used as a mediator for preimplantation embryonic development. Those observations indicate that metabolites of carbohydrate are required by the early embryo, not only as an energy source, but also as a key substrate for other regulatory and biosynthetic pathways. In addition metabolites of carbohydrate may involve in cellular activity during development of preimplantation embryos. It is suggested that through these regulation and with other regulation mechanisms, embryo and uterus can prepare the embryo implantation and further development, properly.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.2
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• pp.212-219
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• 2016

The bioavailability of dissolved organic nitrogen (DON) by dominant species Chaetoceros debilis and Leptocylindrus danicus under dissolved inorganic nitrogen (DIN)-limited condition in the southwestern East Sea was conducted to assess the quantitative evaluation using growth kinetic experiment. Nitrogen sources were nitrate and ammonium as DIN, glycine and urea, which is portion component of DON in East Sea. Maximum specific growth rate (${\mu}_{max}$) and half-saturation constant ($K_s$) of C. debilis calculated from Monod equations were estimated to be $1.50day^{-1}$ and $1.62{\mu}M$ in nitrate, $1.13day^{-1}$ and $6.97{\mu}M$ in ammonium, $1.46day^{-1}$ and $3.36{\mu}M$ in glycine, $0.93day^{-1}$ and $0.55{\mu}M$ in urea, respectively. Also, L. danics was estimated to be $1.55day^{-1}$ and $5.21{\mu}M$ in nitrate, $1.57day^{-1}$ and $4.57{\mu}M$ in ammonium, $1.47day^{-1}$ and $3.80{\mu}M$ in glycine, $1.42day^{-1}$ and $1.94{\mu}M$ in urea, respectively. Both C. debilis and L. dancius have higher affinity of urea than DIN. The high affinity of urea was indicated that the dominant species were able to growth using urea under DIN-limited conditions. Thus, DON utilization of phytoplankton may be one of the important dominant strategy under DIN-limited environments such as southwestern East Sea.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.355-363
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• 2015

The present work quantified the growth of young biofilm in a model distribution system that was fed with chlorinated drinking water at a hydraulic retention time of 2 h. Bacterial biofilms grew on the surface of polyvinyl chloride (PVC) slides at a specific growth rate of $0.14{\pm}0.09day^{-1}$ for total bacteria and $0.16{\pm}0.08day^{-1}$ for heterotrophic bacteria, reaching $3.1{\times}10^4cells/cm^2$ and $6.6{\times}10^3CFU/cm^2$ after 10 days, respectively. The specific growth rates of biofilm-forming bacteria were found to be much higher than those of bulk-phase bacteria, suggesting that biofilm bacteria account for a major part of the bacterial production in this model system. Biofilm isolates exhibited characteristic kinetic properties, as determined by ${\mu}_{max}$ and $K_S$ values using the Monod model, in a defined growth medium containing various amounts of acetate. The lowest ${\mu}_{max}$ value was observed in bacterial species belonging to the genus Methylobacterium, and their slow growth seemed to confer high resistance to chlorine treatment (0.5 mg/L for 10 min). $K_S$ values (inversely related to substrate affinity) of Sphingomonas were two orders of magnitude lower for acetate carbon than those of other isolates. The Sphingomonas isolates may have obligate-oligotrophic characteristics, since the lower $K_S$ values allow them to thrive under nutrient-deficient conditions. These results provide a better understanding and control of multi-species bacterial biofilms that develop within days in a drinking water distribution system.

• Journal of Chest Surgery
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• v.32 no.6
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• pp.567-572
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• 1999

Background: Surgical correction of the full spectrum of esophageal atresia with tracheoesophageal fistula has improved over the years, but the mortality and morbidity assoiated with repair of these anomalies still remains high. Material and Method: We retrospectively analyzes 27 surgically treated patients with esophageal atresia and tracheoesophageal fistula at Dong-A University Hospital between January 1992 and March 1997. Result: There were 21 male and 6 female patients. Mean birth weight was 2.62$\pm$.385 kg(2.0~3.4 kg). Twenty- four(88.9%) had esophageal atresia with distal tracheoesophageal fistula, and 3(11.1%) had pure esophageal atresia. Four(14.8%) infants were allocated to Waterston risk group A, 18(66.7%) to group B, and 5(18.5%) to group C. In eighteen(66.7%) infants with associated anomalies, cardiovascular anomalies were the most common. Three had a gap length of 3.5 cm or greater(ultra-long gap) between esophageal segments, 7 had 2.0 to 3.5 cm(long gap), 8 had 1.0 to 2.0 cm(medium gap), and 9 had 1 cm or less(short gap) gap length. Among 27 neonates, 3 cases underwent staged operation, late colon interposition was done in 2, and all other 24 cases underwent primary esophageal anastomosis. Oerative mortality was 2/27(7.4%). Causes of death included acute renal failure(n=1), empyema from anastomotic leak(n=1), necrotizing enterocolitis(n=1), sepsis(n=1), insulin-dependent diabetus mellitus(n=1 . There were 4 anastomosis- related complications including stricture in 3, leakage in 1. Mortality was related to the gap length(p<.05). Conclusion: Although the complication rate associated with surgical repair of these anomalies is high, this does not always implicate the operative mortality. The overall survival can be improved by effective treatment for combined anomalies and intensive postoperatve care.

• Journal of agricultural medicine and community health
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• v.24 no.1
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• pp.145-159
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• 1999

To find the association, between vinyl house work and the prevalence of low back pain, a questionnaire survey was made toward 215 vinyl house farmers and 228 general farmers without vinyl house who are cared by Jungjung Community health Practioners at Soobuk Myun, Damyang-gun, Chollanamdo. 1. Vinyl house farmers were significantly younger in age, higher in educational status higher survival rate of spouse, higher economic state and less cared by medical aid than general farmers. 2. Vinyl house farmers showed shorter career for agricultural work, used modern farming instrument more frequently and worked with sitting position. 3. During unbusy season in general agriculture, vinyl house farmers consumed significantly more time in agricultural work and general activity, but no significant difference of time of the above activity among busy season. 4. During the last spring season when most vinyl house work was performed, vinyl house farmers showed significantly higher prevalence of low back pain than general farmers, but no significant difference of prevalence among the two groups for the last one week. 5. By the simple analysis statistical significant related variables with low back pain was found to be sex(p<0.001), educational status(p<0.05), work posture(p<0.001) and use of modern agricultural machine(p<0.05). 6. By the multiple logistic regression the odds ratio for low back pain among vinyl house farmers were 2.08(95% confidence interval 1.31-3.00) compared to general farmers, the odds ratio among female was 2.35(95% confidence interval 1.24-4.47) to male, the odds ratio among illiterate persons were 2.60(95% confidence interval 1.24-4.47) to high school graduate, and the odds ration among primary school graduate was 2.19(95% confidence interval 1.04-4.47) to high school graduate. In conclusion because vinyl house farmers showed significantly higher rates of low back pain compared to farmers without vinyl house, continuous study to find the true cause of low back pain among vinyl-house farmers and active effort to prevent low back pain are necessary.

• Clinical and Experimental Pediatrics
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• v.49 no.8
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• pp.857-863
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• 2006

Purpose : To evaluate the immunogenicity of hepatitis B vaccine among very low birth weight infants(VLBWI) who were vaccinated at 0, 1, 6 months of chronological age and to determine the factors associated with antibody formations. Methods : A total of 243 VLBWI admitted to Seoul and Gangneung Asan Medical Center neonatal intensive care units from 1997 to 2004 were included. Of 243, 13 infants were born to HBs Ag positive mother. All infants were given DNA recombinant vaccine at 0, 1, and 6 months of chronological age. Infants born to HBs Ag positive mothers received hepatitis B immunoglobulin at birth and a total of 4 doses of vaccinations. An antibody level over 10 mIU/mL, tested at 3-4 months after last vaccination, was regarded as a positive seroconversion. Results : The seroconversion rates were 84.4 percent and 84.5 percent for VLBWI and extremely low birth weight infants(ELBWI), respectively. Of 28 seronegative infants who were given revaccinations, 60.7 percent seroconverted, resulting in 95.3 percent, 97.5 percent seroconversion rates for VLBWI and ELBWI, respectively. 76.9 percent of infants born to HBsAg positive mothers seroconverted and none became hepatitis B carriers. Factors such as gestational age, sex, various neonatal illness, and kinds of vaccinations did not influence the formation of the hepatits B antibody, however, the higher the weight at time of first vacciation yielded better seroconversion rate. Conclusion : Revaccination of seronegative VLBWI after 3 doses of hepatitis B vaccinaton is very effective. Therefore, testing the immune status after the hepatitis B vaccination, a practice not routinely done, is highly recommended.

• The Journal of Small Business Innovation
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• v.19 no.4
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• pp.1-17
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• 2016

The purpose of this study is to suggest an efficient way for ventures to achieve innovation performance through R&D cooperative arrangements. Achieving innovation is one of the critical factors for the survival of ventures. Unlike established firms, ventures often do not have the specialized assets necessary to take technological developments to the product and market stages. Young and resource-constrained firms can achieve innovation by finding and accessing to the complementary resources from R&D cooperation. In the current business environment, many firms are likely to engage in multiple simultaneous R&D cooperations with different partners. Recent research stream addresses the importance of efficient cooperation management from the holistic portfolio perspective. Since maintaining the multiple cooperative relations require substantial amount of time and effort, managing cooperative relationships play a more important role to resource-constrained firms. In order to find an efficient composition of R&D cooperative partners, we mainly focus on the diversity of partner type and dependence level in partnership. We analyze the data on Korean manufacturing ventures collected in the Korean Innovation Survey (KIS) which was conducted by the Science and Technology Policy Institute (STEPI). The KIS questionnaire assesses the existence of cooperative relationships with different types of partners respectively. The types of cooperating partners are affiliated companies, suppliers, clients & customers, competitors or other firms in the same industry, consulting firms, universities, and research institutes. We confirm that ventures obtain relatively higher benefits from R&D cooperation compared with established firms in terms of innovation performance. The results show that a moderate level of diversity in cooperative partner type composition increases innovation. Moreover, diversity of cooperation dependency among the partners enhances innovation performance. Likewise, concentrating on the quality aspects of cooperative composition, such as diversity of partners and degree of dependencies, this study offers some implications for ventures in managing partners from an integrative perspective.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.2 no.1
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• pp.46-58
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• 1999

Purpose: The aim of the present study was to evaluate the long-term clinical profile including the underlying etioligy and the prognostic factors of the neonatal cholestasis. Method: We studied the 190 infants presented with neonatal cholestasis for the last 12 years (from 1981 to 1992). The underlying causes, clinical findings and long-term outcomes were evaluated. And the prognostic factors were also analyzed. Result: Underlying disease were neonatal hepatitis in 101 (idiopathic in 77 and infectious in 24), intrahepatic bile duct paucity in 5, biliary atresia in 79, choledochal cyst in 5. Metabolic disease was not observed in this study. The important clinical problems during follow-up were persistent high fever, gastrointestinal bleeding, hepatic encephalopathy and ascites. The main causes of the death were hepatic encephalopathy and gastrointestinal bleeding. While three fourth of infants with idiopathic and infectious neonatal hepatitis recovered usually within a year, five-year survival rate for biliary atresia was just 40%, the mortality observed usually within the first year after Kasai operation and prognostic factor was the time of operation. Underlying disease was the most important prognostic factor of neonatal cholestasis. Conclusion: This study showed that most common causes of neonatal cholestasis were biliary atresia and idiopathic neonatal hepatitis, infectious neonatal hepatitis, choledochal cyst and Alagille syndrome, but few neonatal cholestasis of genetic or metabolic liver disease was observed. The most important long-term prognostic factor of neonatal cholestasis was the underlying disease.