• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.1
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• pp.12-18
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• 1985

In general the impulse sound sources of underwater generated by electric arc discharge had used static energy of the charged capacitors. The author proposed an underwater arc discharge sound source using secondary voltage of high voltage transformer without capacitors. The arc discharge device was composed of a high voltage transformer and a switching system. The impulse current in the primary turn of the high voltage transformer is controlled by the switching system and inductive current of the secondary turn in the high voltage transformer is used in making impulsive arc discharge. A series of experiment have been carried out to observe the acoustic characteristics of the impulse sound source generated by the arc discharge. The results obtained were as follows: 1. Secondary current at the time of arc discharge keeps after ohm's law in the beginning and the maximum current flows out as soon as arc discharge breaks out. 2. A time difference between a start of applied current and a generation of arc discharge sound is the 3msec and it is generated arc sound when breaking down electric insulation at maximum voltage. 3. The sharper the end of electrodes and the higher the secondary voltage, the higher the sound pressure level. 4. Arc discharge sound was generated even at the distance of 100cm between electrodes and was stably reproductive at the gap of 1cm to 100cm. 5. Electric arc discharge sound wave is a shock wave of pulse-width of 0.15msec and spectral distribution of it is plenty of low frequency components less than 10 KHz.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.962-967
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• 2010

The influences of the different mixture of urea fertilizer and pig manure compost as a nitrogen (N) source on Chinese cabbage yield, N uptake, and N agronomic efficiency (AE) were evaluated in two soils having different soil fertility levels. Increasing urea application level was very effective to improve yield and N uptake of Chinese cabbage, and the highest yield was obtained by urea fertilization alone in two soils. On the other hand, the lowest yield and N uptake was obtained from compost alone application in two soils. There was no significant difference in terms of the nitrogen AE between low and high fertility soils that were fully applied with urea. The AE values of Chinese cabbage applied by compost alone were significantly higher in the soil having a low fertility (28.8 g $g^{-1}$) than that in soil with high fertility (16.2 g $g^{-1}$), suggesting that N in compost was more responsive in improving the yield of Chinese cabbage in low fertility soils.

• Journal of the Korea Convergence Society
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• v.11 no.6
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• pp.237-248
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• 2020

The purpose of this study is to measure the agricultural product market efficiency of the three e-commerce platforms from the perspective of consumer price fairness perception, analyze the quality and price gap of invalid brands, and help agricultural products enterprises to formulate reasonable price strategies. The characteristics of farm products sold in e-commerce platforms(quality, origin, taste, safety level) were selected as output indicators and the prices of products were selected as input indicators to evaluate the efficiency of the market through DEA analysis. According to the analysis, JD mall has the largest proportion of effective brands, while YHD.com has the highest average market efficiency, and northeast rice has the largest difference in average efficiency among the three platforms. The results show that price inefficiencies still exist in the electronic market. The development of online market for agricultural products should pay attention to consumer price fairness and pay attention to the coordination between price and quality. The limitation of this paper is that it does not focus on the influence of words of mouth marketing in internet market and consumer experience, which can be the future research direction.

• The Journal of Industrial Distribution & Business
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• v.10 no.9
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• pp.37-43
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• 2019

Purpose - The self quality inspection which is mandatory in Republic of Korea can play an important role in promoting food safety, but the cost for self quality inspection is also a big burden especially for small businesses. In addition, excessive or duplicated inspection costs resulting from the standard gaps of various ministries and agencies ultimately effect negative social utility. Thus, this paper aims to suggest ways to improve the analysis of self quality inspection for the Ready-to-Eat Foods in terms of dried laver, in order to reduce costs caused by overinclusion. Research design, data, and methodology - The focus of interest is seaweed in Kimbab, which is to be exempted from the Vibrio parahaemolyticus test on the three grounds. First, existing literature provides little support for the necessity of performing a microbiological test. Second, laver products do not require the V.parahaemolyticus test by international standards such as the CODEX. Third, no case was found for seaweed products on the list of information on failed food items over the 2015~16 period. Results - Other types of seaweed such as exportable and seasoning seaweed are not subject to the test. Hence, exclusion of the V.pahaemolyticus test on seaweed is a valid point, bringing about large expected cost savings to many small businesses. Conclusions - Based on a complete survey of 75 food-testing agencies from March 20th to 30th, 2018, this paper finds that the proposed revision of the Kimbab test is likely to save an average of 130,000 won per business per year. Especially, in the case of the testing fee of Salmonella spp.(n,c,m,M), the cost difference by agencies was found to be up to five times. The regional gap in testing fees can be considered an unfair barrier. Accordingly, it is necessary to examine whether the testing fee is set at an appropriate level through the cost-extraction program proposed by the Ministry Food and Drug Safety. Hence, the survey results also point out that harmonization of testing fees charged by different food-testing agencies is appropriate with respect to transparency and efficiency.

• Korean Journal of Optics and Photonics
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• v.31 no.5
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• pp.205-212
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• 2020

In the performance of a wind turbine system, the blades play a vital role. However, they are susceptible to damage arising from complex and irregular loading (which may even cause catastrophic collapse), and they are expensive to maintain. Therefore, it is very important both to find defects after blade manufacturing is completed and to find damage after the blade is used for a certain period of time. This study provides a new perspective for the detection of internal defects in glass-fiber- and carbon-fiber-reinforced panels, which are used as the main materials in wind turbine blades. A gap or fracture between fiber-reinforced materials, which may occur during blade manufacturing or operation, is simulated by drilling a hole 5 mm in diameter in the middle layer of the laminated material. Then, a digital-image-correlation (DIC) method is used to detect internal defects in the blade. Tensile load is applied to the fabricated specimen using a tensile tester, and the generated changes are recorded and analyzed with the DIC system. In the glass-fiber-reinforced laminated specimen, internal defects were detected from a strain value of 5% until the end of the experiment, while in the case of the carbon-fiber-reinforced laminated specimen, internal defects were detected from 1% onward. It was proved using the DIC system that the defect was detected as a certain level of strain difference developed around the internal defects, according to the material properties.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.103-107
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• 1997

Purpose: To investigate the localization and functional lateralization of the supplementary motor area (SMA) in motor activation tests in comparison to that of the primary motor area. Materials and Methods: Seven healthy volunteers obtained echoplanar imaging blood oxygen level dependent technique. This study was carried on 1.5T Siemens Magnetom Vision system with the standard head coil. Parameters of EPI were followed as; TR/TE : 1.0/66.0msec, flip angle: $90^{\circ}$, field of view: $22cm{\times}22cm,{\;}matrix:{\;}128{\times}128$, slice number/slice thickness/gap: 1O/4mm/0.8mm with fat suppression technique. Motor task as finger opposition in each hand consisted of 3 sets of alternative rest and activation periods. Postprocessing were done on Stimulate 5.0 by using cross-correlation statistics. To compare the functional lateralization of the SMA in the right and left hand tests, each examination was evaluated for the percent change of signal intensity and the number of activated voxels both in the SMA and in the pri¬mary motor area. Hemispheric asymmetry was defined as difference of summation of the activted voxels between each hemisphere. Results: Percent change of signal intensity in the SMA (2.49 -3.06%) is lower than that of primary motor area(4.4 -7.23%). Percent change of signal intensity including activated voxels were observed almost equally in the right and left SMA. As for summation of activated voxels, primary motor area had significant difference between each hemisphere but not did the SMA. Conclusion: Preferred contralateral dominant hemisphere and hemispheric asymmetry were detected in the primary motor area but not in the SMA.

• Korean small business review
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• v.31 no.4
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• pp.67-93
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• 2009

The purpose of this paper is to explore the relations between financial constraints and dividend smoothing of innovative small and medium sized enterprises(SMEs) listed on Korea Securities Market and Kosdaq Market of Korea Exchange. The innovative SMEs is defined as the firms with high level of R&D intensity which is measured by (R&D investment/total sales) ratio, according to Chauvin and Hirschey (1993). The R&D investment plays an important role as the innovative driver that can increase the future growth opportunity and profitability of the firms. Therefore, the R&D investment have large, positive, and consistent influences on the market value of the firm. In this point of view, we expect that the innovative SMEs can adjust dividend payment faster than the noninnovative SMEs, on the ground of their future growth opportunity and profitability. And also, we expect that the financial unconstrained firms can adjust dividend payment faster than the financial constrained firms, on the ground of their financing ability of investment funds through the market accessibility. Aivazian et al.(2006) exert that the financial unconstrained firms with the high accessibility to capital market can adjust dividend payment faster than the financial constrained firms. We collect the sample firms among the total SMEs listed on Korea Securities Market and Kosdaq Market of Korea Exchange during the periods from January 1999 to December 2007 from the KIS Value Library database. The total number of firm-year observations of the total sample firms throughout the entire period is 5,544, the number of firm-year observations of the dividend firms is 2,919, and the number of firm-year observations of the non-dividend firms is 2,625. About 53%(or 2,919) of these total 5,544 observations involve firms that make a dividend payment. The dividend firms are divided into two groups according to the R&D intensity, such as the innovative SMEs with larger than median of R&D intensity and the noninnovative SMEs with smaller than median of R&D intensity. The number of firm-year observations of the innovative SMEs is 1,506, and the number of firm-year observations of the noninnovative SMEs is 1,413. Furthermore, the innovative SMEs are divided into two groups according to level of financial constraints, such as the financial unconstrained firms and the financial constrained firms. The number of firm-year observations of the former is 894, and the number of firm-year observations of the latter is 612. Although all available firm-year observations of the dividend firms are collected, deletions are made in the case of financial industries such as banks, securities company, insurance company, and other financial services company, because their capital structure and business style are widely different from the general manufacturing firms. The stock repurchase was involved in dividend payment because Grullon and Michaely (2002) examined the substitution hypothesis between dividends and stock repurchases. However, our data structure is an unbalanced panel data since there is no requirement that the firm-year observations data are all available for each firms during the entire periods from January 1999 to December 2007 from the KIS Value Library database. We firstly estimate the classic Lintner(1956) dividend adjustment model, where the decision to smooth dividend or to adopt a residual dividend policy depends on financial constraints measured by market accessibility. Lintner model indicates that firms maintain stable and long run target payout ratio, and that firms adjust partially the gap between current payout rato and target payout ratio each year. In the Lintner model, dependent variable is the current dividend per share(DPS_t), and independent variables are the past dividend per share(DPS_t-1) and the current earnings per share(EPS_t). We hypothesized that firms adjust partially the gap between the current dividend per share(DPS_t) and the target payout ratio(Ω) each year, when the past dividend per share(DPS_t-1) deviate from the target payout ratio(Ω). We secondly estimate the expansion model that extend the Lintner model by including the determinants suggested by the major theories of dividend, namely, residual dividend theory, dividend signaling theory, agency theory, catering theory, and transactions cost theory. In the expansion model, dependent variable is the current dividend per share(DPS_t), explanatory variables are the past dividend per share(DPS_t-1) and the current earnings per share(EPS_t), and control variables are the current capital expenditure ratio(CEA_t), the current leverage ratio(LEV_t), the current operating return on assets(ROA_t), the current business risk(RISK_t), the current trading volume turnover ratio(TURN_t), and the current dividend premium(DPREM_t). In these control variables, CEA_t, LEV_t, and ROA_t are the determinants suggested by the residual dividend theory and the agency theory, ROA_t and RISK_t are the determinants suggested by the dividend signaling theory, TURN_t is the determinant suggested by the transactions cost theory, and DPREM_t is the determinant suggested by the catering theory. Furthermore, we thirdly estimate the Lintner model and the expansion model by using the panel data of the financial unconstrained firms and the financial constrained firms, that are divided into two groups according to level of financial constraints. We expect that the financial unconstrained firms can adjust dividend payment faster than the financial constrained firms, because the former can finance more easily the investment funds through the market accessibility than the latter. We analyzed descriptive statistics such as mean, standard deviation, and median to delete the outliers from the panel data, conducted one way analysis of variance to check up the industry-specfic effects, and conducted difference test of firms characteristic variables between innovative SMEs and noninnovative SMEs as well as difference test of firms characteristic variables between financial unconstrained firms and financial constrained firms. We also conducted the correlation analysis and the variance inflation factors analysis to detect any multicollinearity among the independent variables. Both of the correlation coefficients and the variance inflation factors are roughly low to the extent that may be ignored the multicollinearity among the independent variables. Furthermore, we estimate both of the Lintner model and the expansion model using the panel regression analysis. We firstly test the time-specific effects and the firm-specific effects may be involved in our panel data through the Lagrange multiplier test that was proposed by Breusch and Pagan(1980), and secondly conduct Hausman test to prove that fixed effect model is fitter with our panel data than the random effect model. The main results of this study can be summarized as follows. The determinants suggested by the major theories of dividend, namely, residual dividend theory, dividend signaling theory, agency theory, catering theory, and transactions cost theory explain significantly the dividend policy of the innovative SMEs. Lintner model indicates that firms maintain stable and long run target payout ratio, and that firms adjust partially the gap between the current payout ratio and the target payout ratio each year. In the core variables of Lintner model, the past dividend per share has more effects to dividend smoothing than the current earnings per share. These results suggest that the innovative SMEs maintain stable and long run dividend policy which sustains the past dividend per share level without corporate special reasons. The main results show that dividend adjustment speed of the innovative SMEs is faster than that of the noninnovative SMEs. This means that the innovative SMEs with high level of R&D intensity can adjust dividend payment faster than the noninnovative SMEs, on the ground of their future growth opportunity and profitability. The other main results show that dividend adjustment speed of the financial unconstrained SMEs is faster than that of the financial constrained SMEs. This means that the financial unconstrained firms with high accessibility to capital market can adjust dividend payment faster than the financial constrained firms, on the ground of their financing ability of investment funds through the market accessibility. Futhermore, the other additional results show that dividend adjustment speed of the innovative SMEs classified by the Small and Medium Business Administration is faster than that of the unclassified SMEs. They are linked with various financial policies and services such as credit guaranteed service, policy fund for SMEs, venture investment fund, insurance program, and so on. In conclusion, the past dividend per share and the current earnings per share suggested by the Lintner model explain mainly dividend adjustment speed of the innovative SMEs, and also the financial constraints explain partially. Therefore, if managers can properly understand of the relations between financial constraints and dividend smoothing of innovative SMEs, they can maintain stable and long run dividend policy of the innovative SMEs through dividend smoothing. These are encouraging results for Korea government, that is, the Small and Medium Business Administration as it has implemented many policies to commit to the innovative SMEs. This paper may have a few limitations because it may be only early study about the relations between financial constraints and dividend smoothing of the innovative SMEs. Specifically, this paper may not adequately capture all of the subtle features of the innovative SMEs and the financial unconstrained SMEs. Therefore, we think that it is necessary to expand sample firms and control variables, and use more elaborate analysis methods in the future studies.

• Korea journal of population studies
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• v.15 no.2
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• pp.15-59
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• 1992

After world war II Japanese life expectancy has been improved remarkably, and reached the highest level in the world around late 1970's. The life expectancy of Korean has also shown tremendous improvement in recent years with about 20 year's gap from the Japanese. The reason of rapid improvement of life expectancy can be explained by changes in the structure of cause of death due to health system, living standard, social welfare, health behavior of individuals and so on. Korean in Japan is placed under different situations from both Korean in Korea and Japanese in these regards, and expected to show different picture of cause of death pattern. The objective of this study is the comparision of changing patterns of cause of death of three population groups, Korean in Japan, Korean in Korea and Japanese, and to investigate the reasons which effect to the structural difference of mortality cause with special emphasis on health ecological aspects. One of the major limitations of the Korean causes of death statistics is the under-registration which ranges about 10% of the total events, and inaccuracy of the exact cause of death. Some 20% of registered deaths were unable to classify by ICD. However, it is concluded that the Korean data are evaluated as sufficient to stand for over-viewing of trends of cause of death pattern. The evaluation is done by comparing data from registration and field survey over the same population sample. Population data of Korean in Japan differ between two sources of data; census and foreigner's registration. Correction is done by life table method under the assumption that age-specific mortality pattern would accord with that of the Japanese. The crude death rate was lowest among Korean in Japan, 5.7 deaths per 1,000 population in 1965. The crude death rates of Korean in Japan and Japanese are increasing recently influenced by age structure while Korean in Korea still shows decreasing tendency. The adjusted death rate is lowest among Japanese, followed by Korean in Japan, and Korean in Korea. The leading causes of death of Korean in Korea until 1960's was infectious diseases including pneumonia and tuberculosis. The causes of death structure changed gradually to accidents, neoplasm, hypertensive disease, cerebro-vascular disease in order. The main difference in cause of death between Korean and Japanese if high rate of liver diseases and diabetes for both Korean in Japan and Korea. A special feature of cause of death among Korean in Korea is remakably high rate of hypertensive disease, which is assumed to be caused by physicians tendency in choosing diagnostic categories. The low ischemic heart disease and high vasculo-cerebral disease are the distinctive characteristic of the three population groups compared to western countries. Specific causes of death were selected for detailed sex, age and ethnic group comparisons based on their high death rates. Cancer is the cause of death which showed most dramatical increase in all three population groups. In Korea 20.1% of all death were caused by cancer in 1990 compared with 10.5% in 1981. Cancer of the liver is the leading cause of cancer death among Korean in Japan for both sexes, followed by cancer of the lung and cancer of the stomach, while that of Korean in Korea is cancer of the stomach, followed by cancer of the liver and cancer of the lung for male. Causes of infant mortality were examined among the three population groups since 1980 on yearly bases. For both Japanese and Korean in Japan, leading cause of death ranks as conditions originating in the perinatal period, congenital anomalies, accidents and other violent causes. Trends since 1980 for these two population groups in the leading cause of infant mortality showed no changes. On the contrary, significant changes in leading cause of death structure in Korea were observed : the ranking of leading cause of death in 1981 were congenital asnomalies, pneumonia bronchitis, infectious disease, heart disease, conditions originating in the perinatal period, accident and other violent causes ; in 1990 the ranking shifted to congenital anomalies, accident, pneumonia bronchities, conditions originating in the perinatal period, infectious disease. The mortality rate by congenital anomalies in Korea continuously grew than any other causes. Larger increase ocurred during the 1990's

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.48-56
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• 2014

Purpose $^{99m}Tc$-DTPA renal scintigraphy serves as a key indicator to measure a kidney donor's Glomerular Filtration Rate (GFR) and determine the possibility of kidney transplant. The Gates method utilized to measure GFR considers 3 variables of renal depth, injection dose, and net kidney counts. In this research, we seek to compare changes in kidney donors' GFR according to renal depth measurement methods of the 3 variables. Materials and Methods We investigated 32 kidney donors who had visited the hospital from October, 2013 to March, 2014 and received abdominal CT and $^{99m}Tc$-DTPA GFR examination. With the cross-section image of the CT and the lateral image from a gamma camera, we measured the renal depth and compared with renal depth calculation equations-Tonnesen, Taylor, and Itoh methods. Renal depth-specific GFR was calculated by using Xeleris Ver. 2.1220 of GE. Then the results were compared with MDRD (Modification of Diet Renal Disease) GFRs based on serum creatinine level. Results The renal depths measured based on the CT and gamma camera images showed high correlation. Tonessen equation gave the lowest GFR value while the value calculated by using the renal depth of CT image was the highest with a 16.62% gap. MDRD GFR showed no statistically significant difference among values calculated through Taylor, Itoh, CT and gamma camera renal depth application (P>0.05), but exhibited a statistically significant change in the value based on Tonnesen equation (P<0.05). Conclusion This research has found that, in GFR evaluation in kidney donors by utilizing $^{99m}Tc$-DTPA, Tonnesen equation-based Gates method underestimated the value than the MDRD GFR. Therefore, if a MDRD GFR value shows a huge difference from the actual examination value, using an image-based renal depth measurement, instead of Tonnesen equation applied to Gates method, is expected to give an accurate GFR value to kidney donors.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.10
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• pp.1488-1496
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• 2016

The purposes of this study were to analyze mothers' eating, cooking, and exercise habits based on their demographic characteristics and to examine the relationship between those habits and their late school-aged children's Broca index. A total of 393 questionnaires were mailed to the mothers of late school-aged children who registered at four elementary schools in the Seoul area, of which 159 participants (40.0%) completed questionnaires. Statistical data analyses were performed using SPSS/Win 21.0 for descriptive statistics, t-test ANOVA, and Pearson's regression coefficient. There was a statistically significant difference in mothers' cooking habit (F=3.920, P=0.022) and exercise habit (F=3.211, P=0.043) according to their educational level. Interestingly, 82.4% of mothers had a Broca index of less than 90% of normal body mass level. A significant positive correlation of Broca index between mothers and their late school-aged children (r=0.345, P<0.001) indicated that children whose mothers had a low body mass level also tended to have a low body mass level. In this study, late school-aged children's Broca index was not significantly related with mother's eating (r=-0.072, P=0.367) or exercise habits (r=-0.010, P=0.897) but was significantly related with their mother's cooking habits (r=-0.157, P=0.048). Considering there are few studies examining the impacts of mother's cooking habits on their children's appropriate body mass, the results suggest that developing an effective educational program to cultivate mothers' healthy cooking habits to improve school-aged children's health status is very important. The findings of this study provide important data that could be used when developing health education programs tailored to the multi-dimensional impacts of mothers' life habits on their last school-aged children's developmental health status.