• The Journal of the Acoustical Society of Korea
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• v.20 no.2E
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• pp.30-45
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• 2001

This study considers the environmental factors affecting propagation loss and sonar performance in the continental regions of the East Coast Sea of Korea. Water mass distributions appear to change dramatically in a few weeks. Simple calculation with the case when the NKCW (North Korean Cold Water) develops shows that the difference in propagation loss may reach in the worst up to 10dB over range 5km. Another factor, an eddy, has typical dimensions of 100-200km in diameter and 150-200m in thickness. Employing a typical eddy and assuming frequency to be 100Hz, its effects on propagation loss appear to make lower the normal formation of convergence zones with which sonars are possible to detect long-range targets. The change of convergence zones may result in 10dB difference in received signals in a given depth. Thermal fronts also appear to be critical restrictions to operating sonars in shallow waters. Assuming frequency to be 200Hz, thermal fronts can make 10dB difference in propagation loss between with and without them over range 20km. An observation made in one site in the East Coast Sea of Korea reveals that internal waves may appear in near-inertial period and their spectra may exist in periods 2-17min. A simulation employing simple internal wave packets gives that they break convergence zones on the bottom, causing the performance degradation of FOM as much as 4dB in frequency 1kHz. An acoustic experiment, using fixed source and receiver at the same site, shows that the received signals fluctuate tremendously with time reaching up to 6.5dB in frequencies 1kHz or less. Ambient noises give negative effects directly on sonar performance. Measurements at some sites in the East Coast Sea of Korea suggest that the noise levels greatly fluctuate with time, for example noon and early morning, mainly due to ship traffics. The average difference in a day may reach 10dB in frequency 200Hz. Another experiment using an array of hydrophones gives that the spectrum levels of ambient noises are highly directional, their difference being as large as 10dB with vertical or horizontal angles. This fact strongly implies that we should obtain in-situ information of noise levels to estimate reasonable sonar performance. As one of non-stationary noise sources, an eel may give serious problems to sonar operation on or under the sea bottoms. Observed eel noises in a pier of water depth 14m appear to have duration time of about 0.4 seconds and frequency ranges of 0.2-2.8kHz. The 'song'of an eel increases ambient noise levels to average 2.16dB in the frequencies concerned, being large enough to degrade detection performance of the sonars on or below sediments. An experiment using hydrophones in water and sediment gives that sensitivity drops of 3-4dB are expected for the hydrophones laid in sediment at frequencies of 0.5-1.5kHz. The SNR difference between in water and in sediment, however, shows large fluctuations rather than stable patterns with the source-receiver ranges.

• Korean journal of applied entomology
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• v.48 no.2
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• pp.123-158
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• 2009

An attempt was made to stimulate future research by providing exemplary information, which would integrate published knowledge to solve specific pest problem caused by resistance. This review was directed to find a way for delaying resistance development with consideration of chemical(s) nature, of mixture, rotation, or mosaics, and of insecticide(s) compatible with the biological agents in integrated pest management (IPM). The application frequency, related to the resistance development, was influenced by insecticide activity from potentiation, residual period, and the vulnerability to resistance development of chemical, with secondary pest. Chemical affected feeding, locomotion, flight, mating, and predator avoidance. Insecticides with negative cross-resistance by the difference of target sites and mode of action would be adapted to mixture, rotation and mosaic. Mixtures for delaying resistance depend on each component killing very high percentage of the insects, considering allele dominance, cross-resistance, and immigration and fitness disadvantage. Potential disadvantages associated with mixtures include disruption of biological control, resistance in secondary pests, selecting very resistant population, and extending cross-resistance range. The rotation would use insecticides in high and low doses, or with different metabolic mechanisms. Mosaic apply insecticides to the different sectors of a grid for highly mobile insects, spray unrelated insecticides to sedentary aphids in different areas, or mix plots of insecticide-treated and untreated rows. On the evolution of pest resistance, selectivity and resistance of parasitoids and predator decreased the number of generations in which pesticide treatment is required and they could be complementary to refuges from pesticides To enhance the viability of parasitoids, the terms on the insecticides selectivity and factors affecting to the selectivity in field were examined. For establishment of resistant parasitoid, migration, survivorship, refuge, alternative pesticides were considered. To use parasitoids under the pressure of pesticides, resistant or tolerant parasitoids were tested, collected, and/or selected. A parasitoid parasitized more successfully in the susceptible host than the resistant. Factors affecting to selective toxicity of predator are mixing mineral oil, application method, insecticide contaminated prey, trait of individual insecticide, sub-lethal doses, and the developmental stage of predators. To improve the predator/prey ratio in field, application time, method, and formulation of pesticide, reducing dose rate, using mulches and weeds, multicropping and managing of surroundings are suggested. Plant resistance, predator activity, selective insect growth regulator, and alternative prey positively contributed to the increase of the ratio. Using selective insecticides or insecticide resistant predator controlled its phytophagous prey mites, kept them below an economic level, increased yield, and reduced the spray number and fruits damaged.

• Journal of dental hygiene science
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• v.6 no.4
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• pp.271-276
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• 2006

This study set out to analyze the relationships between the senior citizens' dental health activities and dental health conditions, to provide basic data to develop a program for their better dental health, and finally to search for the ways to improve their life quality through dental health care. The subjects were 142 senior citizens(58 were male and 84 were female) who were 65 years old or older and visited a dental hospital or clinic in the Seoul metropolitan area from April 17 to April 28, 2006. With the cooperation from the dentists, the investigators examined their dental conditions and conducted one-on-one interviews to collect the information about their demographic characteristics, dental health activities, and subjective dental health conditions. The collected data were analyzed with T-test, ANOVA and Pearson's correlation coefficient using the SPSS WIN 11.5 program. The analysis results were summarized as follows: First, 58 men(40.8%) and 84 women(59.2%) consisted of the subject group, where percentage of the female participants was bigger Those who were aged from 65 to 69 made the biggest age group in the subjects, accounting for 58.5% with 83. Second, those who had three dental caries or less and then didn't treat them or treated them(F) accounted for the biggest percentage with 117(82.4%) and 72(50.7%) respectively. As for the remaining teeth, the biggest number of them(40 subjects, 28.2%) had three or less remaining. Third, it turned out the female subjects had a higher level of dental health activities than their male counterparts(P = 0.00). As for living expenses, those who were paid salary or earned income themselves carried out their dental health activities in a higher level than those who lived on the benefit from the government(p = 0.02). Fourth, the subjects' subjective dental health conditions had negative correlations with their dental caries not treated. And there were positive correlations between their dental caries not treated and dental caries lost and between their dental caries treated and remaining teeth. Fifth, those subjects who earned their living expenses themselves had the most dental caries treated at 5.4(p = 0.02), and there was statistically significant difference with the numbers. Sixth, those subjects who brushed their teeth in their own manner had 11.8 teeth lost(p = 0.05), which was more than the number of those who brushed their teeth in other methods. And there was statistically significant difference among them. The remaining teeth were found most at 17.3(p = 0.00) among those who brushed their upper and lower teeth separately. In addition, those who visited the public health center often had significantly more teeth treated(4.3) than others(p = 0.00).

• Journal of the Korean earth science society
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• v.37 no.1
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• pp.29-39
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• 2016

In this study, we estimated solar radiation by multiple regression analysis using sunshine duration and precipitation data, which are highly correlated to solar radiation. We found the regression equation using data obtained from GROM (Gangwon Regional Office of Metrology, station 105, 1980-2007) located in Gangneung, South Korea and validated the equation by applying data obtained from new GROM (newly relocated, station 104, 2009-2014) and data obtained from GWNU (Gangneung-Wonju National University, 2013-2014) located between stations 104 and 105. By using sunshine duration data alone, the estimation using data from station 104 resulted in a correlation coefficient of 0.96 and a standard error of $1.16MJm^{-2}$, which was similar to the previous results; the estimation using data from GWNU yielded better results with a correlation coefficient of 0.99 and a standard error of $0.57MJm^{-2}$. By using sunshine duration and precipitation data, the estimation (using data from station 104) yielded a correlation coefficient of 0.96 and a standard error of $0.99MJm^{-2}$, resulting in a lower standard error compared to what was obtained using sunshine duration data alone. The maximum solar radiation bias increased from -26.6% (March 2013) to -31.0% (February 2011) when both sunshine duration and precipitation data were incorporated into the estimation rather than when sunshine duration data alone was incorporated. This was attributed to the concentrated precipitation found during May and July-September, which resulted in negative coefficients of the estimating equation in other months. Therefore, the monthly average solar radiation should be estimated carefully when employing the monthly average precipitation for those places where precipitation is concentrated during summer, such as the Korean peninsula.

• Journal of Gastric Cancer
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• v.9 no.3
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• pp.110-116
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• 2009

Purpose: The aim of this study was to examine the usefulness of positron emission tomography (PET)-computed tomography (CT) in the pre-operative staging of gastric cancer. Materials and Methods: Between February 2006 and August 2008, PET-CT and CT were performed on 70 patients diagnosed with gastric cancer by gastrofiberscopic biopsy. The sensitivities, specificities, Positive predictive value (PPV), and negative predictive value (NPV) of PET-CT and CT imaging for the detection of gastric cancer TNM staging were compared. Results: The detection rates for the primary tumor were as follows: PET-CT, 81.4% (57/70); and CT, 42.9% (30/70). For both early gastric cancer (EGC) and advanced gastric cancer (AGC), PET-CT was more accurate than CT in detecting the lesions. As the size of the tumor exceeded 3 cm, the detection rate increased. The sensitivities, specificities, PPV, and NPV of PET-CT for lymph node staging were 55.6%, 81%, 86.2%, and 45.9%, while the sensitivities, specificities, PPV, and NPV of CT were 40.0%, 85.7%, 85.7% and 40%, respectively. One case of multiple liver metastasis and two cases of dual primary cancer (rectal and pancreatic cancers) were detected by PET-CT. PET-CT also had a higher detection rate for all histologic types of primary tumors. PET-CT was more accurate than CT in detecting primary gastric cancer lesions. The detection of nodal metastasis by PET-CT was similar to CT; small-sized tumors or EGC detection rates were not high. However, PET-CT provided additional information to detect distant metastases and dual primary cancers and reduced unnecessary laparotomies to detect peritoneal seeding or carcinomatosis. Conclusion: It would be useful to make a pre-operative diagnosis of gastric cancer and determine treatment if PET-CT were added to other routine pre-operative studies.

• KDI Journal of Economic Policy
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• v.30 no.1
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• pp.71-130
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• 2008

Using data from the Korean Labor & Income Panel Study (KLIPS), this study investigates private income transfers in Korea, where adult children have undertaken the most responsibility of supporting their elderly parents without well-established social safety net for the elderly. According to the KLIPS data, three out of five households provided some type of support for their aged parents and two out of five households of the elderly received financial support from their adult children on a regular base. However, the private income transfers in Korea are not enough to alleviate the impact of the fall in the earned income of those who retired and are approaching an age of needing financial assistance from external source. The monthly income of those at least the age of 75, even with the earning of their spouses, is below the staggering amount of 450,000 won, which indicates that the elderly in Korea are at high risk of poverty. In order to analyze microeconomic factors affecting the private income transfers to the elderly parents, the following three samples extracted from the KLIPS data are used: a sample of respondents of age 50 or older with detailed information on their financial status; a five-year household panel sample in which their unobserved family-specific and time-invariant characteristics can be controlled by the fixed-effects model; and a sample of the younger split-off household in which characteristics of both the elderly household and their adult children household can be controlled simultaneously. The results of estimating private income transfer models using these samples can be summarized as follows. First, the dominant motive lies on the children-to-parent altruistic relationship. Additionally, another is based on exchange motive, which is paid to the elderly parents who take care of their grandchildren. Second, the amount of private income transfers has negative correlation with the income of the elderly parents, while being positively correlated with the income of the adult children. However, its income elasticity is not that high. Third, the amount of private income transfers shows a pattern of reaching the highest level when the elderly parents are in the age of 75 years old, following a decreasing pattern thereafter. Fourth, public assistance, such as the National Basic Livelihood Security benefit, appears to crowd out private transfers. Private transfers have fared better than public transfers in alleviating elderly poverty, but the role of public transfers has been increasing rapidly since the welfare expansion after the financial crisis in the late 1990s, so that one of four elderly people depends on public transfers as their main income source in 2003. As of the same year, however, there existed and occupied 12% of the elderly households those who seemed eligible for the National Basic Livelihood benefit but did not receive any public assistance. To remove elderly poverty, government may need to improve welfare delivery system as well as to increase welfare budget for the poor. In the face of persistent elderly poverty and increasing demand for public support for the elderly, which will lead to increasing government debt, welfare policy needs targeting toward the neediest rather than expanding universal benefits that have less effect of income redistribution and heavier cost. Identifying every disadvantaged elderly in dire need for economic support and providing them with the basic livelihood security would be the most important and imminent responsibility that we all should assume to prepare for the growing aged population, and this also should accompany measures to utilize the elderly workforce with enough capability and strong will to work.

• Journal of Korean Academy of Nursing
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• v.22 no.4
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• pp.636-652
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• 1992

This study identified the impact of childhood cancer on the Korean family. The purpose was to contribute knowledge for family nursing and pediatric hospice care practice with sick children and their families. This descriptive study was conducted during a 6 month period with children who were being treated for cancer at six university hospitals in Seoul. The data were gathered from members of 68 families ; 24(Group A), with a child newly diagnosed with cancer : 27(Group B), with a child under treatment and without complications, and 17 (Group C), with a child in relapse. Medical records, structured questionnaires and interviews were used for data collection. The questionnaires and interview schedules had been used previously in Martinson's research in the USA and China. The findings, conclusions, and suggestions are as follows. 1. The impact of childhood cancer on the family. Members of the family experienced fear, helplessness, guilty feelings, and anger at the time of the initial diagnosis and at relapse. Mothers complained of headache, anorexia and poor appetite, weight loss, sleep disturbance, and bad dreams. Many of the fathers either lost or changed jobs, and all working mothers stopped working. Half the parents reported changes in their marital relationships such as frequent quarrels but also stronger unity. Family members perceived cancer as the most frightening disease. Change in their world view was expressed as living on faith understanding suffering, determining to live a better life, wanting to live an upright life and valuing health as the most important. Religious activities are found most helpful through this difficult experience. Financial debt due to the treatment and care of the sick child, burdened 22 families. The above mentioned impact was most evidant in Group B(those presently undergoing treatment) and Group C(those in relapse). Findings indicate that nursing care should embrace the family of a child who is being treated for cancer. 2. Characteristics of the child with cancer The majority of the children in this sample had a diagnosis of leukemia. Their mean age was 6.8 and the ratio of boys to girls was 1.12 ; 1. The mean hospitalization frequency was 13.5 times and the mean duration of illness was 16.8 months. Most of 1.he children perceived cancer as the most frightening disease ; 32.7% of the children described their sickness as serious. Children in Group C were hospitalized more frequently, stayed in hospital for longer periods, and expressed their sickness as quite serious more often than the other two groups. These findings indicate how much comprehensive pediatric hospice nursing care services are needed along with relevant research and nursing education. 3. Characteristics of the families. The mean age of the father was 39.5 and the mother, 36,6 ; they are in their most productive life period. Mothers especially expressed feelings of financial uneasiness and powerlessness about giving up their jobs, and guilty feelings for not providing enough care and concern to other children due to taking care of the sick one. The burden of caring for the sick child can bring negative changes in family dynamics which they think provoke potential health problems in members of the family These findings suggest a need for nursing support and counselling resources. Findings also suggest the need for ethical inquiry about such questions as who should give information to the child in regard to diagnosis and prognosis, when, and how. Other suggestions included : 1) Quality health care for childhood cancer such as home care and pediatric hospice programs should be established. 2) Special and practical consideration for long-term patients should be made in the present insurance coverage. The reimbursement period for long-term patients should be lengthened. 3) Further in-depth qualitative studies are needed. 4) Education programs including guided practice experience for pediatric hospice care practitioners are needed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.3
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• pp.75-85
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• 2009

This work proposes a 13b 100MS/s 0.13um CMOS ADC for 3G communication systems such as two-carrier W-CDMA applications simultaneously requiring high resolution, low power, and small size at high speed. The proposed ADC employs a four-step pipeline architecture to optimize power consumption and chip area at the target resolution and sampling rate. Area-efficient high-speed high-resolution gate-bootstrapping circuits are implemented at the sampling switches of the input SHA to maintain signal linearity over the Nyquist rate even at a 1.0V supply operation. The cascode compensation technique on a low-impedance path implemented in the two-stage amplifiers of the SHA and MDAC simultaneously achieves the required operation speed and phase margin with more reduced power consumption than the Miller compensation technique. Low-glitch dynamic latches in sub-ranging flash ADCs reduce kickback-noise referred to the differential input stage of the comparator by isolating the input stage from output nodes to improve system accuracy. The proposed low-noise current and voltage references based on triple negative T.C. circuits are employed on chip with optional off-chip reference voltages. The prototype ADC in a 0.13um 1P8M CMOS technology demonstrates the measured DNL and INL within 0.70LSB and 1.79LSB, respectively. The ADC shows a maximum SNDR of 64.5dB and a maximum SFDR of 78.0dB at 100MS/s, respectively. The ABC with an active die area of $1.22mm^2$ consumes 42.0mW at 100MS/s and a 1.2V supply, corresponding to a FOM of 0.31pJ/conv-step.

• Korean Journal of Plant Resources
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• v.33 no.4
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• pp.255-262
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• 2020

The aim of this study was to investigate the correlation between growth characteristics and ginsenoside contents of 7 and 13-year-old wild-simulated ginseng. The results of growth characteristics such as rhizome length, root length, fresh weight, cross-section area, surface area and volume were shows significantly higher in 13-year-old wild-simulated ginseng compare to 7-year-old wild-simulated ginseng. In the case of 11 ginsenoside contents, the contents of G-Rb1, Rb2, Rc, Rd, Re, Rf, Rg1 and Rg2 were shows significantly higher in 13-year-old wild-simulated ginseng compare to 7-year-old wild-simulated ginseng. In addition, in the comparative analysis of ginsenoside contents between wild-simulated ginseng and cultivated ginseng, 13-year-old wild-simulated ginseng was shows significantly higher G-Rb1, Rd, Re, Rf and Rg1 ginsenoside contents compare to 4-year-old and 5-year-old cultivated ginseng. In the result of correlation analysis between growth characteristics and ginsenoside contents, the G-Rb1, Rb2, Rc, Rd, Re, Rf, Rg1, Rg2 ginsenoside was shows significantly positive correlation with rhizome length, fresh weight, cross-section area, surface area, volume, while as the contents of G-Rb1, Re, Rf, Rg2 was shows significantly negative correlation with shoot diameter. The results of this study was might be help to provide useful information on the establish quality standard by the investigate correlation analysis between growth characteristics and ginsenoside content of wild-simulated ginseng.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.4
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• pp.254-259
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• 1991

The present study was carried out to investigate the effect of nitrogen(urea) application on the seasonal change in pH content of Bray No.1-P, organic matter, and exchangeable cations along the grassland soil profile and further to provide the fundamental information for optimizing the rate of fertilizer application to grassland. Soil samples were taken 20cm intervals upto 100cm soil depth in spring(May 26), summer(July 27), and autumn (October 18) of 1990. The obtained results are summerized as follow 1. In spring and summer, soil pH at 0-20cm soil depth of 28kg N/10a treatment was lowered by 0.7 and 1.0 in comparison with those the same soil depth of 0 kg N/10a treatment and the tendency in pH decrease during all season at the soil depth below 20cm was in the order of summer>spring>autumn. 2. Although Bray No.1-P content at the soil depth 0-20cm of 28kg N/10a treatment was lowered by 20ppm compared to 0 kg N/10a treatment in summer, there was no great difference in its content between 0kg N/10a and 28kg N/10a treatment at all soil depth in spring and summer. In autumn, its content at soil depth below 20cm of 28kg N/10a treatment was higher than that of in summer. 3. Organic matter content at 0-20cm soil depth of 0 and 28kg N/10a treatment in autumn was slightly lowered and on the whole there was very little change in it by soil depth and nitrogen application. 4. The calcium content of 0 and 28kg N/10a treatment was also slightly lowered by increase in soil depth and Mg and K contents were below 0.4 and 0.2 me/100g during all seasons, respectively. 5. Positive correlations were shown among the $NH_4-N$ content and pH, organic matter, Ca and Mg of 0 kg N/10a treatment, however, there was negative correlation ($r=-0.534^{*}$) between $NO_3-N$ content and pH of 28kg N/10a treatment in summer.