• Journal of The Korean Astronomical Society
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• v.50 no.6
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• pp.167-178
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• 2017

We present a study of the inexplicit connection between radio jet activity and ${\gamma}$-ray emission of BL Lacertae (BL Lac; 2200+420). We analyze the long-term millimeter activity of BL Lac via interferometric observations with the Korean VLBI Network (KVN) obtained at 22, 43, 86, and 129 GHz simultaneously over three years (from January 2013 to March 2016); during this time, two ${\gamma}$-ray outbursts (in November 2013 and March 2015) can be seen in ${\gamma}$-ray light curves obtained from Fermi observations. The KVN radio core is optically thick at least up to 86 GHz; there is indication that it might be optically thin at higher frequencies. To first order, the radio light curves decay exponentially over the time span covered by our observations, with decay timescales of $411{\pm}85$ days, $352{\pm}79$ days, $310{\pm}57$ days, and $283{\pm}55$ days at 22, 43, 86, and 129 GHz, respectively. Assuming synchrotron cooling, a cooling time of around one year is consistent with magnetic field strengths $B{\sim}2{\mu}T$ and electron Lorentz factors ${\gamma}$ ~ 10 000. Taking into account that our formal measurement errors include intrinsic variability and thus over-estimate the statistical uncertainties, we find that the decay timescale ${\tau}$ scales with frequency ${\nu}$ like ${\tau}{\propto}{\nu}^{-0.2}$. This relation is much shallower than the one expected from opacity effects (core shift), but in agreement with the (sub-)mm radio core being a standing recollimation shock. We do not find convincing radio flux counterparts to the ${\gamma}$-ray outbursts. The spectral evolution is consistent with the 'generalized shock model' of Valtaoja et al. (1992). A temporary increase in the core opacity and the emergence of a knot around the time of the second ${\gamma}$-ray event indicate that this ${\gamma}$-ray outburst might be an 'orphan' flare powered by the 'ring of fire' mechanism.

• Journal of Korea Water Resources Association
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• v.49 no.5
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• pp.361-372
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• 2016

Reliable long-term dam inflow prediction is necessary for efficient multi-purpose dam operation in changing climate. Since 2000s the teleconnection between global climate indices (e.g., ENSO) and local hydroclimate regimes have been widely recognized throughout the world. To date many hydrologists focus on predicting future hydrologic conditions using lag teleconnection between streamflow and climate indices. This study investigated the utility of teleconneciton for predicting dam inflow with 1-month lead time at Andong dam basin. To this end 40 global climate indices from NOAA were employed to identify potential predictors of dam inflow, areal averaged precipitation, temperature of Andong dam basin. This study compared three different approaches; 1) dam inflow prediction using SWAT model based on teleconneciton-based precipitation and temperature forecast (SWAT-Forecasted), 2) dam inflow prediction using teleconneciton between dam inflow and climate indices (CIR-Forecasted), and 3) dam inflow prediction based on the rank of current observation in the historical dam inflow (Rank-Observed). Our results demonstrated that CIR-Forecasted showed better predictability than the other approaches, except in December. This is because uncertainties attributed to temporal downscaling from monthly to daily for precipitation and temperature forecasts and hydrologic modeling using SWAT can be ignored from dam inflow forecast through CIR-Forecasted approach. This study indicates that 1-month lead dam inflow forecast based on teleconneciton could provide useful information on Andong dam operation.

• Journal of Korea Water Resources Association
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• v.41 no.2
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• pp.149-162
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• 2008

The Soil and Water Assessment Tool (SWAT) developed by the USDA-Agricultural Research Service for the prediction of land management impact on water, sediment, and agricultural chemical yields in a large-scale basin was applied to Daecheong Reservoir basin to estimate the amount of soil losses from different land uses. The research outcomes provide important indications for reservoir managers and policy makers to search alternative watershed management practices for the mitigation of reservoir turbidity flow problems. After calibrations of key model parameters, SWAT showed fairly good performance by adequately simulating observed annual runoff components and replicating the monthly flow regimes in the basin. The specific soil losses from agricultural farm field, forest, urban area, and paddy field were 33.1, $2.3{\sim}5.4$ depending on the tree types, 1.0, and 0.1 tons/ha/yr, respectively in 2004. It was noticed that about 55.3% of the total annual soil loss is caused by agricultural activities although agricultural land occupies only 10% in the basin. Although the soil erosion assessment approach adopted in this study has some extent of uncertainties due to the lack of detailed information on crop types and management activities, the results at least imply that soil erosion control practices for the vulnerable agricultural farm lands can be one of the most effective alternatives to reduce the impact of turbidity flow in the river basin system.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.5
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• pp.371-380
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• 2017

The risk-targeted seismic design concept was first included in ASCE/SEI 7-10 to address problems related to the uniform-hazard based seismic concept that has been constructed without explicitly considering probabilistic uncertainties in the collapse capacities of structures. However, this concept is not yet reflected to the current Korean building code(KBC) because of insufficient strong earthquake data occurred at the Korean peninsula and little information on the collapse capacities of structures. This study evaluates the risk-targeted seismic performance of steel ordinary concentrically braced frames(OCBFs). To do this, the collapse capacities of prototype steel OCBFs are assessed with various analysis parameters including building locations, building heights and soil conditions. The seismic hazard curves are developed using an empirical spectral shape prediction model that is capable of reflecting the characteristics of earthquake records. The collapse probabilities of the prototype steel OCBFs located at the Korean major cities are then evaluated using the risk integral concept. As a result, analysis parameters considerably influence the collapse probabilities of steel OCBFs. The collapse probabilities of taller steel OCBFs exceed the target seismic risk of 1 percent in 50 years, which the introduction of the height limitation of steel OCBFs into the future KBC should be considered.

• Nuclear Engineering and Technology
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• v.4 no.4
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• pp.340-344
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• 1972

Isomeric ratios were measured for the capture of thermal neutron by $^{79}$ Br, $^{80}$ Se, $^{103}$ Rh, $^{115}$ In and $^{133}$ Cs as well as those of epi-cadmium neutron by $^{79}$ Br, $^{80}$ Se and $^{l33}$Cs. The measurements were performed by analysing decay curves obtained by ${\gamma}$-ray spectrometry after irradiation. The counting efficiency curve was determined by using the calibrated standard sources with overall uncertainties of about 1%. Isomeric ratios, given in $\sigma$ high spin/($\sigma$ high spin + $\sigma$ low spin), of $^{80, 80m}$Br, $^{81,81m}$Se, $^{014, 104m}$Rh, $^{116,116m}$In and $^{134, 134m}$Cs produced by thermal neutron activation were found to be 0.21$\pm$0.01, 0.14$\pm$0.02, 0.12$\pm$0.02, 0.69$\pm$0.07 and 0.058$\pm$0.004, respectively, Those values of $^{80, 80m}$Br, $^{81,81m}$Se, and $^{134, 134m}$Cs Produced by epi-cadmium neutron were found to be 0.19$\pm$0.02, 0.29$\pm$0.02 and 0.074$\pm$0.011, respectively. The experimental values obtained were compared with the theoretical values deduced from the statistical model. There were the general agreements between the theory and the experiment.t.

• Journal of Korea Water Resources Association
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• v.42 no.11
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• pp.921-931
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• 2009

For the assessment of climate change impacts for the Byeongseong stream, CGCM 3.1 T63 is selected as future climate information. The projections come from CGCM used to simulate the GHG emission scenario known as A2. Air temperature and precipitation information from the GCM simulations are converted to regional scale data using the statistical downscaling method known as MSPG. Downscaled climate data from GCM are then used as the input data for the SWAT model to generate regional runoff and water quality estimates in the Byeongseong stream. As a result of simple sensitivity analysis, the increase of CO2 concentration leads to increase water yield through reduction of evapotranspiration and increase of soil water. Hydrologic responses to climate change are in phase with precipitation change. Climate change is expected to reduce water yields in the period of 2021-2030. In the period of 2051-2060, stream flow is expected to be reduced in spring season and increased in summer season. While soil losses are also in phase with water yields, nutrient discharges (i.e., total nitrogen) are not always in phase with precipitation change. However, it should be noted that there are a lot of uncertainties in such multiple-step analysis used to convert climate information from GCM-based future climate projections into hydrologic information.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.1
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• pp.97-105
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• 2005

In order to reduce the uncertainties and improve the air flow field, objective analysis using asynoptic observational data is chosen as a method that enhances the reality of meteorology. In surficial data and their numerical interpolation for improving the interpretation of meteorological components, objective analysis scheme should perform a smooth interpolation, detect and remove the bad data and carry out internal consistency analysis. For objective analysis technique which related to data reliability and error suppression, we carried out two quality control methods. In site quality control, asynoptic observational data at urban area revealed low representation by the complex terrain and buildings. In case of wind field, it was more effective than temperature field when it were interpolated near waterbody data. Many roads, buildings, subways, vehicles are bring about artificial heat which left out of consideration on the simulation of air flow field. Therefore, in temperature field, objective analysis for more effective result was obtained when surficial data were interpolated as many as possible using value quality control rather than the selection of representative site.

• Korean Journal of Psychosomatic Medicine
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• v.5 no.1
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• pp.3-11
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• 1997

In becoming parents, the marital partners enter into a new developmental phase. The conception of the child is an act of mutual creativity during which the boundaries between the self and another were temporarily obliterated more completely than at any time since infancy. The infant is a physical fusion of the parents, and their personalities unite within the child. for many women, creativity as a mother becomes a central matter that provides meaning and balance to their lives. The husband usually has strong desires for an offspring and can be transformed by it. The child can profoundly affect one or both parents, and the influences are reciprocal-a child's needs or specific difficulties uncover a parent's inadequacy. following the child's development, each transition into a new developmental phase requires an adaptation by the parents, and one or another of these required adaptations may disturb a parent's equilibirium. And the personality changes, emotional difficulties, and regressions of a spouse that occur in response to some phase of parenthood can upset the marriage. Not only do children identify with parents, but parents also identify with their children. The parents take pleasure in child's joy and suffer with the child's pain more than in almost any other relationship. certain respects e parents lives again in the child. Through the process of identification the child can also provide one of the two parents with the opportunity to experience intimately the way in which a person of the opposite gender grows up. Parenthood also provides the opportunity to be loved, admired, and needed simply because one is a parent and, as such, a central and necessary object in the young child's life. The many potentialities for emotional satisfactions from parenthood manage to outweigh the tribulations and sacrifices that are required. The child also exerts an indirect effect through changing the parent's position in the society, for new sets of relationships are established as the parents are drawn to other couples with children of the same age, and for a new impetus toward economic and social mobility often possesses the parents. frequently the couple's relatedness to their own parents improves and grows firmer once again. Parenthood, the satisfactions it provides and the demands it makes, varies as life progresses : and changes with the parent's interests, needs, and age as well as with the children's maturation. There are phases in the child's life that the parents are reluctant to have pass, whereas they tolerate others largely through knowing that they will soon be over. The changing lives of the children provide many satisfactions that offset the tribulations, uncertainties, and regrets. The parents change. The young father, who was just starting on his carrier whom the first child was born, settles into a life pattern. He becomes secure with increasing achievement and interacts differently with the youngest child and provides a different model for him than for the oldest. The mother may have less time for a second or third child than for her first, but she may also be more assured in her handling of them. The birth of a baby when the parents art in their late thirties will find them Less capable of physical exertion with the child and less tolerant of annoyances, but they are less apt to be annoyed. Eventually the children min and leave home, but the couple do not cease to be parents.

• Journal of Korea Water Resources Association
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• v.46 no.4
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• pp.425-437
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• 2013

This study performed the bivariate drought frequency analysis for duration and severity of drought, using copula functions which allow considering the correlation structure of joint features of drought. We suggested the confidence intervals of duration-severity-frequency (DSF) curves for the given drought duration using stochastic scheme of monthly rainfall generation for 57 sites in Korea. This study also investigated drought risk via illustrating the largest drought events on record over 50 and 100 consecutive years. It appears that drought risks are much higher in some parts of the Nakdong River basin, southern and east coastal areas. However, such analyses are not always reliable, especially when the frequency analysis is performed based on the data observed over relatively short period of time. To quantify the uncertainty of drought frequency curves, the droughts were filtered by different durations. The 5%, 25%, 50%, 75%, and 95% confidence intervals of the drought severity for a given duration were estimated based on the simulated rainfall time series. Finally, it is shown that the growing uncertainties is revealed in the estimation of the joint probability using the two marginal distributions since the correlation coefficient of two variables is relatively low.

• Journal of Environmental Policy
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• v.8 no.4
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• pp.25-36
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• 2009

The Total Pollutant Load Management System(TPLMS) in the Han River basin is being changed from a voluntary to a mandatory system. Accordingly, this study suggests directions and priorities for research that can support implementation of TPLMS through an objective approach that deploys gap analysis and analytic hierarchy processes (AHP). Gap analysis indicated that TPLMS in Korea is still focused on compliance with regulations, and that implementation of TPLMS is still in its early stage. Improvements are thus needed in flexibility and effectiveness, including introduction of emissions rights trading, and upgrading to a renewable emissions permit system. The AHP study indicated that R&D will need to proceed in parallel in multiple areas to improve systems and resolve scientific uncertainties. Balanced R&D will be needed in both the institutional and technical groups. Subgroup analysis indicated that developing a reasonable process to establish water quality management targets is of the highest priority in the institutional group. In the technical group, higher priority will need to be given to improving model reliability and developing innovative pollution load reduction technologies.