• Journal of the Korean Institute of Gas
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• v.24 no.2
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• pp.1-8
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• 2020

Centrifugal pump is a facility that transfers energy to fluid through centrifugal force, which is usually generated by rotating the impeller at high speed, and is a major process facility used in many LNG production bases such as vaporization seawater pump, industrial water and fire extinguishing pump using seawater. to be. Currently, pumps in LNG plant sites are subject to operating conditions that vary depending on the amount of supply desired by the customer for a long period of time. Pumps in particular occupy a large part of the consumption strategy at the plant site, and if the optimum operation condition is not available, it can incur enormous energy loss in long term plant operation. In order to solve this problem, it is necessary to identify the performance deterioration factor through the flow analysis and the result analysis according to the fluctuations of the pump's operating conditions and to determine the optimal operation efficiency. In order to evaluate operation efficiency through experimental techniques, considerable time and cost are incurred, such as on-site operating conditions and manufacturing of experimental equipment. If the performance of the pump is not suitable for the site, and the performance of the pump needs to be reduced, a method of changing the rotation speed or using a special liquid containing high viscosity or solids is used. Especially, in order to prevent disruptions in the operation of LNG production bases, a technology is required to satisfy the required performance conditions by processing the existing impeller of the pump within a short time. Therefore, in this study, the rotation difference of the pump was applied to the ANSYS CFX program by applying the modified 3D modeling shape. In addition, the results obtained from the flow analysis and the curve fitting toolbox of the MATLAB program were analyzed numerically to verify the outer diameter correction theory.

• KDI Journal of Economic Policy
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• v.30 no.2
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• pp.225-270
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• 2008

We analyze macroeconomic consequences of pay-as-you-go (PAYGO) public pension system with a simple overlapping generations model. Contrary to large body of existing literatures offering quantitative results based on simulation study, we take another route by adopting a highly simplified framework in search of qualitatively tractable analytical results. The main contribution of our results lies in providing a sound theoretical foundation that can be utilized in interpreting various quantitative results offered by simulation studies of large scale general equilibrium models. We present a simple overlapping generations model with a defined benefit(DB) PAYGO public pension system as a benchmark case and derive an analytical equilibrium solution utilizing graphical illustration. We also discuss the modifications of the benchmark model required to encompass a defined contribution(DC) public pension system into the basic framework. Comparative statics analysis provides three important implications; First, introduction and expansion of the PAYGO public pension, DB or DC, result in lower level of capital accumulation and higher expected rate of return on the risky asset. Second, it is shown that the progress of population aging is accompanied by lower capital stock due to decrease in both demand and supply of risky asset. Moreover, risk premium for risky asset increases(decreases) as the speed of population aging accelerates(decelerates) so that the possibility of so-called "the great meltdown" of asset market cannot be excluded although the odds are not high. Third, it is most likely that the switch from DB PAYGO to DC PAYGO would result in lower capital stock and higher expected return on the risky asset mainly due to the fact that the young generation regards DC PAYGO pension as another risky asset competing against the risky asset traded in the market. This theoretical prediction coincides with one of the firmly established propositions in empirical literature that the currently dominant form of public pension system has the tendency to crowd out private capital accumulation.

• Investigative Magnetic Resonance Imaging
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• v.17 no.3
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• pp.215-223
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• 2013

Purpose : To evaluate the effect of gadoxetic acid on the measurement of the stiffness value of MR elastography (MRE) used to evaluate hepatic fibrosis (HF). Materials and Methods: MRE was obtained in 32 patients with clinically suspected chronic liver disease, both before and after injection of gadoxetic acid. Two independent reviewers measured the stiffness values of the liver parenchyma on elastograms. The mean liver stiffness values were compared in the pre- and post-contrast MREs using the paired t-test. Intra-rater and inter-rater correlation was assessed using the intraclass correlation coefficient (ICC). The accuracy, sensitivity, and specificity of both pre- and post-contrast MREs was evaluated for the diagnosis of significant HF (${\geq}F2$) using cut off value of 3.1 kPa. Results: There were no significant differences in the stiffness values of the liver parenchyma on pre- and post-contrast MREs (p = 0.15 and 0.38 for each reader, respectively). Regarding intra-rater correlation, excellent agreement was noted on rater 1(ICC = 0.998) and rater 2 (ICC = 0.996). Excellent correlation regarding the measured stiffness values was noted on both pre- and post-contrast MREs (ICC = 0.988 for pre-contrast, ICC = 0.993 for post-contrast). The accuracy, sensitivity, and specificity of the pre- and post-contrast MREs for differentiating significant HF (${\geq}F2$) from ${\geq}F1$ were same as 71%, 60%, and 100%, respectively. Conclusion: As there was no significant difference in the stiffness measurements seen on MREs before and after administration of gadoxetic acids, it is therefore acceptable to perform MRE after contrast injection in order to evaluate HF.

• Korean Journal of Agricultural Science
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• v.26 no.2
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• pp.39-48
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• 1999

This study was carried out to investigate the difference and genetic similarity at the level of molecular genetics. Genomic DNA was extracted from blood of Holstein, Korean cattle, Charolais, and hybrid between Korean cattle and charolais and RAPD(random amplified polymorphic DNAs) was analyzed by PCR(polymerase chain reaction). After genetic similarity value from different breeds are analyzed, genetic similarity was estimated by UPGMA(unweighted pair-group method using average). The results obtained from this study can be summarized as follows: 1. When genomic DNA which was extracted from different breeds was subjected to electrophoresis on 1.5% agarose gel, bigger than 12.2kb was appeared. Ratio by absorbance of $A_{260}/A_{280}$ was 1.75~2.10, indicating that genomic DNA was quite pure for RAPD analysis. 2. Different band patterns by RAPD were appeared according to the breeds in cattle. The best primer used to distinguish Holstein from other breeds was 5'-GAC CGC TTG T-3'. 3. A 340bp fragment was amplified in $33.0^{\circ}C$ of annealing temperature for the Holstein and Charolais breeds, but any amplification was not occurred in this annealing temperature for Korean cattle and hybrid. In addition, a 340bp fragment was amplified in $37.5^{\circ}C$ of annealing temperature for the Holstein and Korean cattle, but any amplification was not occurred in this annealing temperature for Charolais and hybrid. For the reaction of PCR. $37.5^{\circ}C$ and $33.0^{\circ}C$ of annealing temperature was shown to be best for genetic marker identification from Holstein, Charolais, and hybrid between Korean cattle and Charolais. 4. When genetic similarity from different breeds are analyzed at the both temperature of $33.0^{\circ}C$ and $37.5^{\circ}C$, the genetic similarity value of Holstein and Korean cattle, Holstein and Charolais, Korean cattle and Charolais, and Korean cattle and hybrid were 0.666~0.777, 0.615~0.666, 0.400~0.461 and 0.857~0.888, respectively. 5. It could be concluded that different breeds are capable of distinguishing by RAPD used random primer 5'-GAC CGC TTG T-3', genetic similarity from different breeds was appeared the higher genetic similarity value of Korean cattle and Charolais than that of Holstein between Korean cattle and Charolais by UPGMA.

• Management & Information Systems Review
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• v.35 no.1
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• pp.51-68
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• 2016

In this paper, we aim to analyze the effect of accounting policy change subsequent to the adoption of K-IFRS in Korea, whereby the firms are required to recognize impairment losses on goodwill on a periodic basis rather than to amortize over a specific period. As a principle-based accounting standard, the K-IFRS expands the scope of fair value measurement with a view to enhance the relevance and timeliness of accounting information. In the same vein, intangibles with indefinite useful life, of which goodwill is an example, are subject to regulatory impairment tests at least once a year. Related literature on the impact of mandatory change in goodwill policy document that impairment recognition is more likely to be practiced opportunistically, mainly because managers have a greater discretion to conduct the tests under K-IFRS. However, existing literature examined the frequency and/or magnitude of the goodwill impairment before versus after the K-IFRS adoption, failing to notice the impairment symptoms at individual firm level. Borrowing the definition of impairment symptoms suggested by Ramanna and Watts(2012), this study performs a series of tests to determine whether the goodwill impairment recognition achieves the goal of communicating timelier information under the K-IFRS regime. Using 947 firm-year observations from domestic companies listed in KRX and KOSDAQ markets from 2008 to 2011, we document overall delays in recognizing impairment losses on goodwill after the adoption of K-IFRS relative to prior period, based on logistic and OLS regression analyses. The results are qualitatively similar in robustness tests, which use alternative proxy for goodwill impairment symptom. Afore-mentioned results indicate that managers are likely to take advantage of the increased discretion to recognize the impairment losses on goodwill rather than to provide timelier information on impairment, inconsistent with the goal of regulatory authority, which is in line with the improvement of timeliness and relevance of accounting information in conjunction with the full implementation of K-IFRS. This study contributes to the extant literature on goodwill impairment from a methodological viewpoint. We believe that the method employed in this paper potentially diminishes the bias inherent in researches relying on ex post impairment recognition, by conducting tests based on ex ante impairment symptoms, which allows direct examination of the timeliness changes between before and after K-IFRS adoption.

• Sleep Medicine and Psychophysiology
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• v.5 no.1
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• pp.88-102
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• 1998

Objectives : We attempted to study obstructive sleep apnea symptoms prevalence and sleep apnea-associated factors in Korean rural adult population. Methods : In 1,441 adult subjects of three rural communities selected by cluster sampling, we administered an epidemiologic survey using questionnaire methods from July 14, 1996 to July 28, 1996. Results : 1) In 14.1% of the subjects, snoring was reported to occur almost daily and 2.9% of the subjects reported sleep apnea symptoms occurring almost daily. 2) Snoring and sleep apnea symptoms were found more frequently in males or in mid-aged group(45 - 64 years old) than in females or in younger- and older-aged groups, respectively. Compared with the subjects who have no snoring, the subjects who have snoring or sleep apnea symptoms had greater body mass index(BMI), waist-hip ratio, hemoglobin level, RBC count, and higher diastolic blood pressure. 3) Cigarette smoking and alcohol drinking more than once a week were significantly associated with suffering from sleep apnea symptoms. 4) In multiple logistic regression analysis, being male, mid-aged, and greater BMI were independently associated with the presence of snoring and sleep apnea symptoms. Conclusion : We conclude that, in the Korean rural adult population, males or mid-aged group suffers more from snoring and sleep apnea symptoms than females or younger- and older-aged groups. In addition, being male, mid-aged, and greater BMI were significantly associated independently with the presence of snoring and sleep apnea symptoms.

• Clinical and Experimental Reproductive Medicine
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• v.34 no.2
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• pp.87-94
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• 2007

Objective: To examine determinants of successful pregnancy and evaluate COH-IVF outcomes of infertile patients after conservative surgical treatment of borderline ovarian tumor (BOT). Methods: In women of BOT (n=93), from January 1995 to December 1999, 44 of 93 women underwent conservative surgical treatment. From theses 44 women, patients characteristics, surgical and histological parameters were compared between 14 women who conceived and 30 women who failed to conceive. For 5 infertile women of 30 women who failed to conceive, 10 attempt IVF cycles were analysed; clinical pregnancy rate (CPR), implantation rate (IR) and live birth rate (LBR). Results: Women who conceived tend to be younger (25.9 vs 27.0 years) and lower serum CA-125 level (59.7 vs 72.9) compared to women who failed to conceive without significant difference. For 8 cycles out of 10 attempt IVF cycles, except for 2 cancellation cycles, the mean number of oocytes retrieved was 5.6 (range 2$\sim$16) with a mean fertilization rate of 74.4%. The CPR, IR and LBR per embryo transfer were 50.0% (4/8 cycles), 31.6% (6/19) and 50.0% (4/8 cycles) respectively. During the mean follow-up period after COH-IVF initiation, 29.6 (range 14$\sim$61) months, no recurrence was found. Conclusion: No determinant of successful pregnancy was found after conservative treatment for BOT. COH-IVF may be considered for infertile patients after conservative treatment of BOT. However, larger clinical studies with longer follow-up are necessary to evaluate the safety and efficacy of COH-IVF. All patients should be informed of the potential risks associated with ovarian hyperstimulation and close follow-up is necessary after COH-IVF.

• Journal of Life Science
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• v.25 no.4
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• pp.463-472
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• 2015

Adrenomedullin (AM) is a peptide expressed in all body tissues, and its related receptors are increased in liver fibrosis. In this study, we evaluated the effect of AM deficiency on liver fibrogenesis induced by $CCl_4$ using AM heterozygous (HT) mice. The animals received a single injection of $CCl_4$ or olive oil for the acute experiment, and received $CCl_4$ or olive oil three times a week for 6 weeks for the chronic experiment. Fibrosis was accessed using histopathological analysis and the western blot. The AM HT mice showed mild pericentrilobular degeneration when compared to the AM wild type (WT) mice. In the acute experiment, there was no significant difference between the AM WT and AM HT mice. However, in the chronic experiment, the $CCl_4$-treated AM HT mice showed more severe liver fibrosis than that of the CCl₄-treated AM WT mice. The AST and ALT levels of the AM HT $CCl_4$ group were higher than those of the AM WT CCl₄ group. Additionally, the collagen deposition, $\alpha$- SMA protein and TGF-$\beta$ protein were increased in the AM HT $CCl_4$ group when compared to the AM WT $CCl_4$ group. The AM HT mice also exhibited severe lipid peroxidation through the GSH decrement. Taken together, our data suggest that AM deficiency increases the susceptibility to liver fibrosis induced by $CCl_4$, indicating a novel therapeutic target for patients with liver fibrosis.

• Tuberculosis and Respiratory Diseases
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• v.54 no.5
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• pp.563-569
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• 2003

Background : Pleural effusions with high amylase levels are reported frequently in patients with pancreatic diseases, a rupture of the esophagus and a malignancy. However, there is no data available on the clinical features of an amylase-rich pleural effusion in Korea. This report describes the causes of the high amylase levels in a pleural effusion and analyzes its association with malignancy. Methods : The records of patients with an amylase-rich pleural effusion who were assessed at the Gyeongsang National University Hospital from January 1998 to August 2002 were examined retrospectively, and the distribution of amylase levels in those patients, the causative diseases, and the histological type in the case of a malignancy were analyzed. Among the 532 patients whose pleural effusion was evident on a chest X-ray, there were 36 cases with an amylase-rich pleural effusion. The amylase levels were determined by an enzyme method (Hitach 747 autoanalyzer). Results : Of the 36 patients with an amylase-rich pleural effusion, there were 18 patients(50%) associated with a malignancy, 8 patients(22%) with a parapneumonic effusion, 7 patients(19%) with pancreatic disease, and 3 patients with other causes. The amylase level in a pleural effusion due to pancreatic disease was much higher than that due to other causes(p<0.01). Among the malignant pleural effusions with high amylase levels, the origin of the malignancy was a primary lung cancer in 13 cases and metastatic lung cancer in 5 cases. The histological types of malignant causes were adenocarcinoma in 10 cases(56%), squamous cell carcinoma in 2 cases(11%) and unknown type of carcinoma in 6 cases. The amylase level in the adenocarcinoma cases was much higher than that in the other cell type carcinomas(p<0.01). There was no significant association between the amylase level and the glucose level among the malignant cases with amylase-rich pleural effusion(p=0.21). Conclusion : The most frequent cause of an amylase-rich pleural effusion was a malignancy. Primary lung cancer and adenocarcinoma were the most common malignancies and histological types associated with a malignant pleural effusion with high amylase levels. The amylase level in a pleural effusion secondary to pancreatic disease was much higher than from any other causes.

• Journal of Gastric Cancer
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• v.7 no.3
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• pp.167-173
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• 2007

Purpose: Mistletoe (Viscum album L.) extract is one of the most widely used agents in alternative cancer therapeutic regimens in Europe. This study was conducted to determine the effect of mistletoe extract on immune function in gastric cancer patients. Materials and Methods: Ten patients that had undergone a curative gastrectomy were enrolled in the prospective study. ABNOBAviscum $Q^{(R)}$ was injected subcutaneously three times a week from postoperative-day 7 to week 16 with an increasing dose. All of the patients simultaneously received chemotheraphy with mitomycin, oral 5-FU and a cisplatin regimen. The WBC count, differential count, lymphocyte/WBC ratio and the level of cytokines (IL-$1{\beta}$, IL-2, IL-6, IFN-$\gamma$, TNF-$\alpha$) were checked in the peripheral blood preoperatively, at postoperative week 8 and at postoperative week 16. Results: The WBC and neutrophil counts significantly decreased after treatment on week 8 and week 16 (P=0.001), but the total eosinophil count was slightly increased (P=0.15). The total lymphocyte count also decreased during treatment but the lymphocyte/WBC ratio was slightly increased without statistical significance (P=0.91). The cytokine levels did not significantly change during treatment. Conclusion: It is somewhat difficult to determine the direct effect of mistletoe therapy on immune function as the effect may be compromised by the concurrent chemotherapy. It can be assumed that the slightly increased lymphocyte/WBC ratio and eosinophil count may be a result of the immunomodulatory effect of the mistletoe extract.