• Structural Engineering and Mechanics
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• v.76 no.6
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• pp.687-708
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• 2020

Openings in steel plate shear walls (SPSWs) are usually used for decorative designs, crossing locations of multiple utilities and/or structural objectives. However, earlier studies showed that generating an opening in an SPSW has a negative effect on the cyclic performance of the SPSW. Therefore, this study proposes tripling or doubling the steel-sheet-plate (SSP) layer and stiffening the opening of the SPSW to provide a solution to undesirable opening effects, improve the SPSW performance and provide the infill option of potential strengthening measures after the construction stage. The study aims to investigate the impact of SSP doubling with a stiffened opening on the cyclic behaviour, expand the essential data required by structural designers and quantify the SPSW performance factors. Validated numerical models were adopted to identify the influence of the chosen parameters on the cyclic capacity, energy dissipation, ductility, seismic performance factors (SPF) and stiffness of the suggested method. A finite Element (FE) analysis was performed via Abaqus/CAE software on half-scale single-story models of SPSWs exposed to cyclic loading. The key parameters included the number of SSP layers, the opening size ratios corresponding to the net width of the SSP, and the opening shape. The findings showed that the proposed assembly method found a negligible influence in the shear capacity with opening sizes of 10, 15, 20%. However, a deterioration in the wall strength was observed for openings with sizes of 25% and 30%. The circular opening is preferable compared with the square opening. Moreover, for all the models, the average value of the obtained ductility did not show substantial changes and the ultimate shear resistance was achieved after reaching a drift ratio of 4.36%. Additionally, the equivalent sectional area of the SSP in the twin and triple configuration of the SPSWs demonstrated approximately similar results. Compared with the single SSP layer, the proposed configuration of the twin SSP layer with a stiffened opening suggest to more sufficiency create SSP openings in the SPSW compared to that of other configurations. Finally, a tabular SPF quantification is exhibited for SPSWs with openings.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.697-703
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• 2022

Due to the recent economic downturn caused by Covid-19 and the unstable international situation, many investors are choosing the derivatives market as a means of investment. However, the derivatives market has a greater risk than the stock market, and research on the market of market participants is insufficient. Recently, with the development of artificial intelligence, machine learning has been widely used in the derivatives market. In this paper, reinforcement learning, one of the machine learning techniques, is applied to analyze the scalping technique that trades futures in minutes. The data set consists of 21 attributes using the closing price, moving average line, and Bollinger band indicators of 1 minute and 3 minute data for 6 months by selecting 4 products among futures products traded at trading firm. In the experiment, DNN artificial neural network model and three reinforcement learning algorithms, namely, DQN (Deep Q-Network), A2C (Advantage Actor Critic), and A3C (Asynchronous A2C) were used, and they were trained and verified through learning data set and test data set. For scalping, the agent chooses one of the actions of buying and selling, and the ratio of the portfolio value according to the action result is rewarded. Experiment results show that the energy sector products such as Heating Oil and Crude Oil yield relatively high cumulative returns compared to the index sector products such as Mini Russell 2000 and Hang Seng Index.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.3
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• pp.138-147
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• 2007

An emergy concept was used to evaluate the environment and economy of the Han River basin in Korea and to suggest policy perspectives far the sustainable utilization of its environment and associated estuarine ecosystem. The economy of the basin used $5.19{\times}10^{23}\;sej/yr$ of emergy in 2005. The economy of the Han River basin was heavily dependent on outside energy sources from foreign countries and other parts of Korea, with internal sources, renewable and nonrenewable, contributing only 15.6% to the total emergy use. The basin's trade balance in terms of emergy showed trade surplus, whereas there was a deficit in monetary terms. The population of the Han River basin was far greater than the carrying capacity calculated using the emergy flow, with renewable carrying capacity only at 1.8% of the basin's population and developed carrying capacity at 14.3%. The economy of the basin imposed a substantial stress on its environment, with an environmental loading ratio of 54.8. Overall, the economy of the Han River basin was not sustainable with an emergy sustainability of 0.02. These are reflected in lower quality of living expressed in the emergy term than the national average. Deconcentration of population and economic activities is needed to reduce environmental stress on the environment of the basin and its valuable estuarine ecosystem. Policies to restore ecosystem productivity of the basin are also needed to ensure the sustainability of the basin's economic activities and the sustainable utilization of the Han River estuary. In this regard, it is urgently needed for the Korean government to implement sustainable management measures for the Han River estuary, a well-preserved, productive natural estuarine ecosystem in Korea.

• Journal of agriculture & life science
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• v.53 no.5
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• pp.137-143
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• 2019

To manufacturing of solid fuel by reuse of the wastes, the drying unit which have 500 kg/hr of drying capacity was developed and experimentally evaluate the performance. The spinach grown in Nam-hae island were used for the experiments and investigated of the heated-air drying characteristics as the inlet amount of raw materials, raw material stirring status, conveying type and drying time. The drying air heated by the energy derived from the steam which is supplied from the incineration plant. The moisture contents of raw materials were measured 85.65%. The inlet flow rate of drying air made a difference as the depth of the raw materials loaded on the drying unit and temperature has showed 108~144℃. The drying speed of the mixed drying more than doubled as that of non mixed drying under the same drying type, inlet amount, drying time and drying air temperature. In each experiment, the drying capacity have showed over 500 kg/hr. A drying efficiency of the ratio of drying consumption energy to input energy was 33.46%, lower than the average of 57.76% for the 157 conventional dryers. Because developed dryer must have a drying time of less than one hour, it is considered that the dry efficiency has been reduced due to the loss of wind volume during drying. If waste heat from incineration plant is used as a direct heat source, the dry air temperature is expected to be at least 160℃, greatly improving the drying capacity.

• Economic and Environmental Geology
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• v.55 no.2
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• pp.209-217
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• 2022

The purpose of this study was to confirm the dissolution of arsenic from the stabilized soil around abandoned coal mines by cultivation activities. Experimental soils were collected from the agricultural field around Okdong and Buguk coal mines, and the concentration of arsenic in the soil and the geochemical mobility were confirmed. The average arsenic concentration was 20 mg/kg. The soil with relatively high geochemical mobility of arsenic in the soil was used in the batch and column experiment. The limestone was mixed with soil for soil stabilization, and the mixing ratio was 3% of limestone, based on the soil weight. The phosphoric acid fertilizer (NH₄H₂PO₄) was added to the soil to simulate a cultivation condition according to the Rural Development Administration's rules. Comparative soil without mixing limestone was prepared and used as a control group. The arsenic extraction from soil was increased following the fertilizer mixing amount and it shows a positive relationship. The concentration of phosphate in the supernatant was relatively low under the condition of mixing limestone, which is determined to be result of binding precipitation of phosphate ions and calcium ions dissolved in limestone. Columns were set to mix phosphoric acid fertilizers and limestone corresponding to cultivation and stabilization conditions, and then the column test was conducted. The variations of arsenic extraction from the soil indicated that the stabilization was effectible until 10 P.V.; however, the stabilization effect of limestone decreased with time. Moreover, the geochemical mobility of arsenic has transformed by increasing the mobile fractions in soil compared to initial soil. Therefore, based on the arsenic extraction results, the cultivation activities using phosphoric fertilizer could induce a decrease in the stabilization effect.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.1
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• pp.1-13
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• 2006

A field survey on the spatio-temporal distribution characteristics and origins of organic matter in surface sediments was carried out monthly at six stations in Gamak Bay, South Korea from April 2000 to March 2002. The range of ignition loss(IL) was $4.6{\sim}11.6%(7.1{\pm}1.6%)$, while chemical oxygen demand(CODs) ranged from $12.25{\sim}99.26mgO_2/g-dry(30.98{\pm}19.09mgO_2/g-dry)$, acid volatile sulfide(AVS) went from no detection(ND)${\sim}10.29mgS/g-dry(1.02{\pm}0.58mgS/g-dry)$, and phaeopigment was $6.84{\sim}116.18{\mu}g/g-dry(23.72{\pm}21.16{\mu}g/g-dry)$. The ranges of particulate organic carbon(POC) and particulate organic nitrogen(PON) were $5.45{\sim}23.24 mgC/g-dty(10.34{\pm}4.40C\;mgC/g-dry)$ and $0.71{\sim}2.99mgN/g-dry(1.37{\pm}0.58mgN/g-dry)$, respectively. Water content was in the range of $43.1{\sim}77.6%(55.8{\pm}5.6%)$, and mud content(silt+clay) was higher than 95% at all stations. The spatial distribution of organic matter in surface sediments was greatly divided between the northwestern, central and eastern areas, southern entrance area from the distribution characteristic of their organic matters. The concentrations of almost all items were greater at the northwestern and southern entrance area than at the other areas in Gamak Bay. In particular, sedimentary pollution was very serious at the northwestern area, because the area had an excessive supply of organic matter due to aquaculture activity and the inflow of sewage from the land. These materials stayed longer because of the topographical characteristics of such as basin and the anoxic conditions in the bottom seawater environment caused by thermocline in the summer. The tendency of temporal change was most prominently in the period of high-water temperatures than low-water ones at the northwestern and southern entrance areas. On the other hand, the central and eastern areas did not show a regular trend for changing the concentrations of each item but mainly showed a higher tendency during the low-water temperatures. This was observed for all but AVS concentrations which were higher during the period of high-water temperature at all stations. Especially, the central and eastern areas showed a large temporal increase of AVS concentration during those periods of high-water temperature where the concentration of CODs was in excess of $20mgO_2/g-dry$. The results show that the organic matters in surface sediments in Gamak Bay actually originated from autochthonous organic matters with eight or less in average C/N ratio including the organic matters generated by the use of ocean, rather than terrigenous organic matters. However, the formation of autochthonous organic matter was mainly derived from detritus than living phytoplankton, indicated the results of the POC/phaeopigment ratio. In addition, the CODs/IL ratio results demonstrate that the detritus was the product of artificial activities such as dregs feeding and fecal pellets of farm organisms caused by aquaculture activities rather than the dynamic of natural ocean activities.

• Korean Journal of Agricultural Science
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• v.8 no.2
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• pp.195-202
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• 1981

The return of water to the atmosphere from water, soil and vegetation surface is one of the most important aspects of hydrological cycle, and the seasonal trend of variation of river basin evaporation is also meaningful in the longterm runoff analysis for the irrigation and water resources planning. This paper has been prepared to show some imformation to estimate the monthly river basin evaporation from pan evaporation, potential evaporation, regional evaporation and temperature through the comparison with river basin evaporation derived from water budget method. The analysis has been carried out with the observation data of Yongdam station in the Geum river basin for five year. The results are summarized as follows and these would be applied to the estimation of river basin evaporation and longterm runoff in ungaged station. 1. The ratio of pan evaporation to river basin evaporation ($E_w/E_{pan}$) shows the most- significant relation at the viewpoint of seasonal trend of variation. River basin evaporation could be estimated from the pan evaporation through either Fig. 9 or Table-7. 2. Local coefficients of cloudness effect and wind function has been determined to apply the Penman's mass and energy transfer equation to the estimation of river basin evaporation. $R_c=R_a(0.13+0.52n/D)$ $E=0.35(e_s-e)(1.8+1.0U)$ 3. It seems that Regional evaporation concept $E_R=(1-a)R_C-E_p$ has kept functional errors due to the inapplicable assumptions. But it is desirable that this kind of function which contains the results of complex physical, chemical and biological processes of river basin evaporation should be developed. 4. Monthly river basin evaporation could be approximately estimated from the monthly average temperature through either the equation of $E_w=1.44{\times}1.08^T$ or Fig. 12 in the stations with poor climatological observation data.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.8
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• pp.1311-1319
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• 2004

The purpose of this study was to compare the serum lipid level, blood sugar and blood pressure in vegetarians and non-vegetarians. The subjects of the study were 127 Buddhist nuns (age: 23∼79 y) from Oonmoon Temple in Choungdo district Gyeongsang Bookdo province and 118 Buddhist nuns practicing Zen meditation at Soodeok Temple in Yeosan district Chongcheong Namdo province. For control subjects, 235 healthy female adults (age: 23∼79 y) were selected. They were the nurses in the Gyeongsang National University Hospital, teachers and housekeepers living in Jinju, Gyeongsang Namdo province. The period of this study was from October 1996 to February 1997. The contents were consisted of food consumption survey, anthropometric measurement, estimated amount of energy expenditure, physical activity and clinical examination. The mean ages of the subjects were 44.2 y for vegetarians and 40.5 y for non-vegetarians, respectively. Average body mass index (BMI) of vegetarians and non-vegetarians were 22.47 and 21.08, WHR 0.85 and 0.84, percentage of body fat 28.79 and 26.55 respectively. The average duration of vegetarian diet of the vegetarians was 13.16 y. Levels of total cholesterol, LDL-cholesterol, atherogenic index (AI), diastolic blood pressure, blood sugar and HDL-cholesterol were significantly higher (p<0.01) in non-vegetarians than those of vegetarians. In both of subjects, levels of TG, total cholesterol, LDL-cholesterol, atherogenic index (AI) and systolic blood pressure were significantly higher (p<0.01) with an increment of age and the vegetarians showed a lower ratio of rise than the non-vegetarians. Levels of serum TG, LDL-cholesterol and AI were utmost in the 60 s and declined in the 70 s. Consequently, vegetarian diet can be considerably effective in reducing the level of the risk factors causing cardiovascular disease.

• Journal of Nutrition and Health
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• v.45 no.2
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• pp.140-149
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• 2012

The purpose of this study was to compare nutrient intake and diet quality of obese women to those of non-obese women, and to investigate the relationship between diet quality and obesity index in females. We analyzed data from the combined 2007-2009 Korean National Health and Nutrition Examination Survey (KNHANES). In this study, according to their BMI (above $25kg/m^2$), we classified the subjects into the obese group (n = 724) and non-obese control group (n = 2,841). Nutrient adequacy ratio (NAR), the number of foods (Dietary Variety Score, DVS), and food groups consumed (Dietary Diversity Score, DDS) were analyzed by using the data from the 24-recall method. The average energy intake of both the obese and control group were 1634.94 kcal and 1,707.81 kcal, respectively (p = 0.0199). The obese group consumed significantly lower quantities of calcium per 1,000 kcal compared to the control group (p = 0.0261). With regards to diet quality, calcium NAR in the obese group was significantly lower than that of the control group (p = 0.0158). MAR values for the obese and the control group was 0.79 and 0.80, respectively and revealed no statistical difference. The obese group showed a significantly lower consumption of milk compared to the control group (p = 0.0162). The average DVS of the obese and control group was 28.63 and 30.41, respectively and revealed a statistical significance (p = 0.0003). DDS in the obese group (3.686) was significantly lower than that of the control group (3.769)(p = 0.0253). DVS showed considerable negative relationships with BMI or waist circumference after it was adjusted for potential confounding factors. In conclusion, obese women had lower calcium intake quality, milk consumption, DVS and DDS than those of the control group. In Korean females, food intake variety did adversely affect obesity index. Further studies are needed to confirm this finding.

• Journal of Nutrition and Health
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• v.43 no.3
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• pp.224-232
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• 2010

The prevalence of heart failure (HF) is increasing globally and growing evidence has shown that dietary factors play an important role in preventing and improving prognosis of HF. However, little data on nutrient intake in Korean HF patients which are available to develop dietary guidelines for HF. The aims of this study were to estimate nutrient intake in 78 HF patients and evaluate whether the estimated nutrient intake is appropriate compared to dietary reference intake for Koreans. Data are presented as the ratio of actual intake and estimated average requirement (EAR) for each nutrient. The result showed that the average nutrient intakes including total energy and protein met EAR in total patients. However, the deficiencies in mineral and vitamin intakes were found. Moreover, the proportion of subjects with lower intake than EAR was substantial. The results showed that the proportion of male HF patients with inferior intakes to EAR in calcium, potassium (compared to adequate intake: AI), folate and vitamin $B_{12}$ were 38%, 79%, 38%, and 65%, respectively. Also, the proportion of female HF patients with inferior intakes to EAR in calcium, potassium (compared to AI), folate and vitamin $B_{12}$ were 35%, 88%, 38% and 40%, respectively. In particular, the elderly with HF ($\geq$ 70 yrs, n = 28) showed more serious deficiencies in calcium, potassium (compared to AI), folate and vitamin $B_{12}$. In summary, the intakes of potassium, calcium, folate, and vitamin B12 were not sufficient to meet EAR in HF patients. Furthermore, the proportions of subjects with lower intake than EAR in these nutrients were substantial, raising the possibility that these micronutrients may be involved in the pathogenesis of HF. Practical dietary guideline for HF patients is needed to improve prognosis of HF.