• KDI Journal of Economic Policy
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• 제31권1호
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• pp.169-206
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• 2009

This study stems from a question, "How should we understand the pattern of the Korean economy after the 1990s?" Among various analytic methods applicable, this study chooses a Structural Vector Autoregression (SVAR) with long-run restrictions, identifies diverse impacts that gave rise to the current status of the Korean economy, and differentiates relative contributions of those impacts. To that end, SVAR is applied to four economic models; Blanchard and Quah (1989)'s 2-variable model, its 3-variable extensions, and the two other New Keynesian type linear models modified from Stock and Watson (2002). Especially, the latter two models are devised to reflect the recent transitions in the determination of foreign exchange rate (from a fixed rate regime to a flexible rate one) as well as the monetary policy rule (from aggregate targeting to inflation targeting). When organizing the assumed results in the form of impulse response and forecasting error variance decomposition, two common denominators are found as follows. First, changes in the rate of economic growth are mainly attributable to the impact on productivity, and such trend has grown strong since the 2000s, which indicates that Korea's economic growth since the 2000s has been closely associated with its potential growth rate. Second, the magnitude or consistency of impact responses tends to have subsided since the 2000s. Given Korea's high dependence on trade, it is possible that low interest rates, low inflation, steady growth, and the economic emergence of China as a world player have helped secure capital and demand for export and import, which therefore might reduced the impact of each sector on overall economic status. Despite the fact that a diverse mixture of models and impacts has been used for analysis, always two common findings are observed in the result. Therefore, it can be concluded that the decreased rate of economic growth of Korea since 2000 appears to be on the same track as the decrease in Korea's potential growth rate. The contents of this paper are constructed as follows: The second section observes the recent trend of the economic development of Korea and related Korean articles, which might help in clearly defining the scope and analytic methodology of this study. The third section provides an analysis model to be used in this study, which is Structural VAR as mentioned above. Variables used, estimation equations, and identification conditions of impacts are explained. The fourth section reports estimation results derived by the previously introduced model, and the fifth section concludes.

• Archives of Pharmacal Research
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• 제23권1호
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• pp.1-16
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• 2000

Many natural products elicit diverse pharmacological effects. Using two classes of potential chemopreventive compounds, the phenolic compounds and the isothiocyanates, we review the potential utility of two signaling events, the mitogen-activated protein kinases (MAPKs) and the ICE/Ced-3 proteases (caspases) stimulated by these agents in mammalian cell lines. Studies with phenolic antioxidants (BHA, tBHQ), and natural products (flavonoids; EGCG, ECG, and isothiocyanates; PEITC, sulforaphane), provided important insights into the signaling pathways induced by these compounds. At low concentrations, these chemicals may activate the MAPK (ERK2, JNK1, p38) leading to gene expression of survival genes (c-Fos, c-Jun) and defensive genes (Phase II detoxifying enzymes; GST, QR) resulting in survival and protective mechanisms (homeostasis response). Increasing the concentrations of these compounds will additionally activate the caspase pathway, leading to apoptosis (potential cytotoxicity). Further increment to suprapharmacological concentrations will lead to nonspecific necrotic cell death. The wider and narrow concentration ranges between the activation of MAPK/gene induction and caspases/cell death exhibited by phenolic compounds and isothiocyanates, respectively, in mammalian cells, may reflect their respective therapeutic windows in vivo. Consequently, the studies of signaling pathways elicited by natural products will advance our understanding of their efficacy and safety, of which many man become important therapeuitc drugs of the future.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• 제10권1호
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• pp.147-159
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• 2000

The NIOSH health hazard evaluation program (HHE program) was created in response to the mandate to determine the toxic effect and potential health hazard of workplace exposure, which is found in Occupational Safety and Health Act of 1970 and the Federal Mine Safety and Health Act of 1977, A primary benefit of HHE program is its ability to provide current health hazard data to employers and employees, which assists them in identifying solutions to occupational health and safety problems in their workplaces, The HHE program also stimulates research in the development and review of sampling methods and diagnostic tests and may prompt additional exposure assesment efforts and toxicological and epidemiological studies. HHE projects also provide human exposure-toxicity data that are used to asses the validity of existing occupational health standards and to support criteria for new standards of recommendation, The HHE request is classified into four categories: 1) category 1: As a administratively invalid, 2) category 2: These are valid requests for which a site visit is not essential to an appropriate response, 3) Category 3 : These are valid requests for which a site visit is necessary for an adequate evaluation, 4) These are valid request which present a complex problem or an opportunity for research, To carry out HHE program one or methods of investigation might be used: 1) direct observation and evaluation of production processes and employee work practices 2) employees exposure level and air contamination level 3) medical test or physical examinations of employees 4) private, confidential interviews with employees 5) review of employer's record of injuries and illness, employee exposure data, medical tests and job histories. After investigation and analysing the data, NIOSH issues a final report, giving finding and recommendation.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제13권3호
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• pp.373-384
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• 2000

To assess the safety of nonlinear steel frame structures subjected to short duration dynamic loadings, especially seismic loading, a nonlinear time domain reliability analysis procedure is proposed in the context of the stochastic finite element concept. In the proposed algorithm, the finite element formulation is combined with concepts of the response surface method, the first order reliability method, and the iterative linear interpolation scheme. This leads to the stochastic finite element concept. Actual earthquake loading time-histories are used to excite structures, enabling a realistic representation of the loading conditions. The assumed stress-based finite element formulation is used to increase its efficiency. The algorithm also has the potential to evaluate the risk associated with any linear or nonlinear structure that can be represented by a finite element algorithm subjected to seismic loading or any short duration dynamic loading. The algorithm is explained with help of an example and verified using the Monte Carlo simulation technique.

• The Korean Journal of Quaternary Research
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• 제14권1호
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• pp.65-71
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• 2000

The growth of Daphniphyllum macropodum at Mt. Naejang National Park(Naejang temple area) was investigated in connection with the climatic factors by the use of tree-ring analysis. A pair of cores was extracted from each of 18 trees in the D. macropodum community area near Younjabong for the analysis. The period of mater chronology based upon D. macropodum covers from 1915 to 1998. The growth rates of D. macropodum were very poor in the years 1920, 1932, 1934, 1937, 1942, 1946, 1964, 1969 and 1985, respectively. Response function was employed to understand the relationship between the growth of D. macropodum and climatic factors. The response function of the growth rates of D. macropodum indicated significant negative correlation with the precipitation of August and September. Poor growth of D. macropodum during the August and September nay be due to the frequent rain periods during the summer The heavy rain during the summer seems to decrease the solar radiation, which eventually caused the decrease of photosynthesis capacity. In conclusion, we hypothesize that the decrease of the photosynthesis rates during the rainy summer seasons may cause the slower growth of D. macropodum.

• Korean Journal of Health Education and Promotion
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• 제21권1호
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• pp.171-182
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• 2004

Objectives： Smoking, especially among youth, has been increasing in Korea. This study was performed to evaluate the effects of a newly developing well-designed packaged smoking prevention program (PSPP) for middle school students and to propose further ideas about the program. Methods： The subjects were middle school students enrolled in one Busan city middle school. The effects of the PSPP were evaluated through intervention and follow-up. The PSPP was executed for 10 hours during the semester of middle school freshmen by the author as a position of health teacher, from 1999. After PSPP, cognitions and experiences about smoking were assessed annually from February, 2000 to 2002 by questionnaire. The responses of the educated group and the non-educated group (enrolled in the school at 1998) were compared through chi-square test and odds ratio (OR) and 95％ confidence interval (CI) using SPSS program (ver 10.0). Results： In the three years' follow-up study on the students enrolled in 1999, the proportion of habitual smoking increased significantly (p＜0.001); freshmen 0.2％, sophmore 1.7％, junior 5.0％. However, these level were lower than the results of national study； freshmen 1.1 ％, sophmorer 6.3％, junior 8.5％. Also, the risk of smoking based on the response of 'smoking is hazardous to my health' increased by higher grading. In the comparison of educated and non-educated group, the proportion of the habitual smoking was significantly lower in the educated group(5.0％) than in the non-educated group(13.5％) (OR [95％CI]＝0.33 [0.20∼0.57]). The response rate of 'smoking is hazardous to my health' was higher (OR [95％CI]＝4.42 [2.52∼7.77]), and that of 'maybe smoking in the future' was lower (OR [95％CI]＝0.43 [0.31∼0.59]) in the educated group than in the non-educated group. Conclusions： Though there is not enough information and it was a relatively short evaluation period, this PSPP is considered to be effective in smoking prevention in middle school students. Interests and continuity would be emphasized for the success of smoking prevention programs for younger subjects.

• Journal of the Korean Society for Nondestructive Testing
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• 제20권1호
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• pp.33-37
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• 2000

The 1-3 piezoelectric composite transducer with 75 volume percents PZT was fabricated by the dicing-filling method. The resonance modes of the 1-3 transducer have been studied with electric impedance measurement as a function of frequency. The fundamental frequencies of the planar and thickness mode were observed at 0.95MHz and 1.63MHz respectively, but the lateral mode was not observed. In the thickness mode, the electromechanical coupling coefficient of the 1-3 piezoelectric composite transducer, 0.54, was very closed to that of the single phase PZT(0.52). The pulse-echo response by exciting the 1-3 transducer with an electric pulse was observed from the water/reflector interface, and analyzed bandwidth by the spectrum of the impulse response. The quality factor Q for the 1-3 transducer was observed as 1.5 smaller than that of the single phase(80) and then the 1-3 transducer may be used to the broad band type transducer applications.

• Journal of the Korean Society for Nondestructive Testing
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• 제20권1호
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• pp.38-45
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• 2000

In this research, MFL technique has been studied for the inspection of storage tank floor. The reference specimens having 20%, 40%, 60% and 80% slot's are fabricated using the carbon steel plates of a 6mm and 10mm thick. Powerful permanent magnets and Hall effect sensors are used to this application. It is shown that our system is able to detect metal loss like a slot. Also, it is possible that slot diameter is measured using transverse type of Hall generator. It is demonstrated that MFL can not differentiate between the response from top side and bottom side slot. Flux leakage response from a bottom side indication is significantly lower in amplitude than that from an equivalent top side slot. It is essential to know this sensor lift-off distance because the MFL signal also changes considerably with the sensor lift-off distance.

• Korean Journal of Veterinary Research
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• 제40권3호
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• pp.575-585
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• 2000

This study was performed to observe the influence of host immune response on the chemotherapy of mice experimentally infected with Fasciola hepatica. Following immunosuppression with prednisolone or immunoenhancement with Freund's complete adjuvant(FCA), mice were experimentally infected with 3 Fasciola hepatica metacercariae and treated with closantel at 1 week post infection. In the group of mice infected with metacercariae alone, 2 mice of 10 were dead at 10 weeks post infection(20% mortality), and adult flukes were recovered from the liver and the peritoneal cavity of the remaining 8 mice(100% infectivity). In the group of mice treated with prednisolone and infected with metacercariae, 8 of 10 mice died before euthanasia with a mean time of death earlier than the control group (p<0.05). In the group of immunosuppressed mice infected with metacercariae and treated with closantel 20mg/kg, 4 of 10 mice died before sacrifice. In the group of mice infected and treated with closantel 20mg/kg, mortality and infectivity was 10% and 30%, respectively. Similar results were observed in mice infected and treated with closantel 5mg/kg which resulted in 10% and 50% mortality and infectivity, respectively. These results indicated that the efficacy of closantel treatment was decreased in immunosuppressed mice, while the pathogenicity was increased. In immunoenhanced mice infected with metacercariae, on the other hand, the efficacy of chemotherapy with both 5mg/kg or 20mg/kg closantel resulted in only 10% infectivity. The results shown in this study strongly suggest that a close interaction between chemotherapy against F hepatica with closantel and the host immune system exists. Considering that fascioliasis is a zoonosis, treatment regimen against the infection to immunosuppressed patients may require a concurrent prescription of an appro-priate immuno-enhancing adjuvant.

• The Korean Journal of Pain
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• 제13권2호
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• pp.242-246
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• 2000

Radiofrequency medial branch neurotomy is an effective way of controlling pain in the posterior compartment of the spine such as the facet joint, and the interspinous ligament. However, it is difficult to determine the exact location of the medial branch. Up until now we have relied on sensory response provoked by 50 Hz stimulation. The responses elicited using this method are quite subjective and can originate from sources other than the medial branch such as the periosteum, the intermediate or lateral branch. We need a confirmed indicator to locate the medial branch reliably. We applied 2 Hz stimulation under 0.4 volts to locate the medial branch and elicited a motor response. Twitching of multifidus and muscles around the SI joint was observed. The observation of these muscles provides a much more reliable method for confirmation of the medial branch. We have treated 45 chronic nonspecific low back pain patients using radiofrequency medial branch neurotomy with this method of confirming the medial branch.