• Journal of agriculture & life science
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• v.44 no.5
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• pp.109-116
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• 2010

This study was carried out to evaluate effects of distance and difference of ground level between two natural ventilating pig houses on their ventilation by using simulation. Distance between two pig houses was 6 or 12 m. Difference of ground level between two pig houses was 0 or 2 m. Mean air velocities in summer and winter were designated to 1.3 and 1.1 m/s. Under the conditions of summer, air velocities in all the pig houses in south were about 0.75 m/s regardless of distance and difference of ground level between two pig houses and air velocities in the second pig houses in north were about 0.75 m/s at difference of ground level of 0m and about 0.0 m/s at difference of ground level of 2 m, respectively. Under the conditions of winter, air velocities in all the pig houses in south were about 0.15 m/s regardless of distance and difference of ground level between two pig houses and air velocities of the second pig houses in north were about 0.0 m/s at distance of 6 m and about 0.15 m/s at distance of 12 m, respectively. Therefore, it is suggested that the optimum distance and difference of ground level between two natural ventilating pig houses might be 12 m and 0 m.

• Journal of agriculture & life science
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• v.44 no.6
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• pp.121-132
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• 2010

Soybean farms in Changnyeong were selected for hazard analysis to establish the Good Agricultural Practices (GAP) model of soybean, and physical, chemical(heavy metal) and biological(sanitary indications, foodborne pathogens) hazard analysis for cultivation environment (soil, water) was carried out. First, bow which is able to be mixed in soil and water was confirmed as physical hazard. Levels (Cd:0.01~0.103, Cu:0.001~6.036, As:0.006~3.045, Hg:ND~0.041, Pb:0.003~3.952, $Cr^{+6}$:0.007~0.496, Zn:0.001~66.500, Ni:0.003~18.010) of heavy metals in soil and water were appropriate for GAP criteria. In biological hazard, APC and coliform in soil were detected at the levels of $6.0{\pm}0.3$ and $3.6{\pm}1.6$ log CFU/g, and levels of water were $3.5{\pm}0.7$ and $1.9{\pm}0.7$ log CFU/mL, while E. coli wasn't detected in all sample. However, coliform in water wasn't appropriate for criteria, and E. coli O157 was detected about 22% in some farms, so it needs ways to prevent contamination by human and animals excrements. In conclusion, it needs proper management to prevent cross-contamination of hazards although physical and chemical hazard level were appropriate for GAP criteria while biological hazard wasn't.

• Korean Journal of Social Welfare Studies
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• v.44 no.3
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• pp.421-450
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• 2013

One of the challenging tasks of the National Health Insurance Corporation(NHIC). the only public insurance institution administrating the Korea's compulsory national health insurance(NHI) system, is to make those NHI beneficiaries who fail to make a scheduled monthly premium payment to pay. For this purpose, the NHIC has been using a measure known as 'Benefit Limit Measure(BLM)' in which those who miss premium payment for six or more month's in total are classified as 'late payer' and are sent warnings and late payer status notices. If the late payers fail to make a full payment of missed premiums even after receiving the written notices, the NHIC can order a temporary seizure of the late payer's property until all missed premiums plus interest are paid. Recently, the BLM has been criticized by the public of its cruel nature, and its effectiveness has been questioned because no empirical evidence has been collected. In this study, the authors using the NHIC data set attempted to analyze the effectiveness of the BLM. Those late payers for whom the BLM was administered were compared to those not in terms of the likelihood of paying missed premium payments with a series of logistic regression analyses models. Data analyses results showed that the likelihood of paying one or more month's unpaid premium of the former group was 14 to 46 times higher than the latter. It, however, was also found that the BLM was only effective to make no more than 12% of the late payers to pay at all. Based on the study findings, the authors made a few recommendations regarding the BLM.

• Journal of Korea Port Economic Association
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• v.34 no.4
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• pp.1-16
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• 2018

The standard shift-share analysis decomposes a region's sectoral growth into three components: national, industry-mix, and regional-shift effects. Nevertheless, the three components of the traditional shift-share are not related to the behavior of the regional economies that are neighbors of the region under analysis. We incorporate a spatial structure within this basic formulation, and consider spatial interaction in the decomposition analysis. Daesan Port's export grew steadily at an annualized average rate of 4.0% during 2011-2017, and its rank, in terms of export performance, was 13 in 2010; this rose to 6 in 2016, then declined slightly to 7 in 2017 before reaching 6 as of June, 2018. However, not all ports have a similar growth path. The Onsan Port's share declined from 27.4% in 2011 to 21.0% to 2017, whereas the share of petroleum product exports of Daesan Port increased rapidly, from approximately 8.5% in 2011 to 16.0% in 2017. The standard shift-share analysis shows that petroleum products and basic petrochemicals have a positive regional in dustry-mix effect, but petrochemistry materials and synthetic resins have a negative sign, indicating that the former's exports grow faster than national export, while the increase of the latter's export is slower than national one. The spatial shift-share model indicates that for both petroleum products and basic petrochemicals, Incheon and Ulsan Ports have a positive value for the neighbor-nation regional shift effect and a positive value for the region-neighbor regional shift effect. This paper also shows that Yeosu Port for petroleum products; Ulsan Port for basic petrochemicals; Ulsan, Onsan and Yeosu Ports for petrochemistry materials; and Ulsan, Busan, and Incheon Ports for synthetic resins have a positive value for the neighbor-nation regional shift effect but a negative value for the region-neighbor regional shift effect.

• Elastomers and Composites
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• v.45 no.4
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• pp.263-271
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• 2010

Intermittent CSR testing was used to investigate the degradation of an FKM O-ring, also the prediction of its life-time. An intermittent CSR jig was designed taking into consideration the O-ring's environment under use. The testing allowed observation of the effects of friction, heat loss, and stress relaxation by the Mullins effect. Degradation of O-rings by thermal aging was observed between 60 and $160^{\circ}C$. In the high temperature of range ($100-160^{\circ}C$) O-rings showed linear degradation behavior and satisfied the Arrhenius relationship. The activation energy was about 60.2 kJ/mol. From Arrhenius plots, predicted life-times were 43.3 years and 69.9 years for 50% and 40% failure conditions, respectively. Based on TTS (time-temperature superposition) principle, degradation was observed at $60^{\circ}C$, and could save testing time. Between 60 and $100^{\circ}C$ the activation energy decreased to 48.3 kJ/mol. WLF(William-Landel-Ferry) plot confirmed that O-rings show non-linear degradation behavior under $80^{\circ}C$. The life-time of O-rings predicted by TTS principle was 19.1 years and 25.2 years for each failure condition. The life-time predicted by TTS principle is more conservative than that from the Arrhenius relationship.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.981-986
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• 2010

This study was carried out to investigate the effects of fertilizer and organic resource annual dressing for 30 years of Jeonbug series (silt loam) on soil properties and rice N uptake in paddy field soil. In the study field, treatments including control (NPK), NPK+rice straw, NPK+rice straw compost and nitrogen fertilization levels at 0, 100, 150, 200, 250 kg $ha^{-1}$ have been imposed for 30 years. Soil hardness and bulk density decreased from 15.7 mm and 1.381 Mg $m^{-3}$ in the control to 12.5 mm and 1.244 Mg $m^{-3}$ in NPK+rice straw compost treatment, respectively, indicating improvement of soil physical conditions such as porosity. Co-application of straw compost with NPK also result in a better chemical properties than NPK alone as it increased available phosphate (from 96 to 133 mg $kg^{-1}$), available silicate (from 81 to 116 mg $kg^{-1}$), and cation exchange capacity (from 9.8 to 11.4 $cmol_c\;kg^{-1}$). Soil organic matter concentration of top soil (0 to 7.5 cm in depth) was higher in NPK+rice straw and NPK+rice straw compost than in control. Fertilizer N uptake amount was much higher in NPK+rice straw (nitrogen fertilization level; 250 kg $ha^{-1}$) and NPK+rice straw compost (nitrogen fertilization levels; 200, 250 kg $ha^{-1}$) plots compared to the control (nitrogen fertilization level; 100 kg $ha^{-1}$) plot. Nitrogen use efficiency was showed significantly high in the NPK+rice straw compost (nitrogen fertilization levels; 100, 150 kg $ha^{-1}$) plot compared to the control (nitrogen fertilization level; 100 kg $ha^{-1}$) plot. Therefore, it was suggested that application of organic inputs is helpful in improving soil fertility and physical conditions and thus in N uptake.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.930-936
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• 2010

There is very important to investigate long-term trend of soil chemical properties and quality index for sustainable agriculture and production of agricultural safety products. Monitoring on soil chemical properties in paddy soils was conducted as one cycle with 4 years from 1999 to 2007. Paddy soil samples were taken from 4,007, 1,970, 2,070 sites in 1999, 2003 and 2007, respectively. With these data, soil quality index (SQI) was evaluated by method that Yoon et al suggested in 2004. Chemical properties of paddy soils were 5.8 for pH, 24 g $kg^{-1}$ for organic matter, 132 mg $kg^{-1}$ for available phosphate, 0.29 cmol_c\; kg-1 for exchangeable potassium, 4.7 $cmol_c\;kg^{-1}$ for exchangeable calcium, 1.3 $cmol_c\;kg^{-1}$ for exchangeable magnesium and 126 mg $kg^{-1}$ for available silicate in 2007. Long-term change was shown that pH has increased gradually whereas exchangeable potassium has decreased. However, reasonably large changes were found. Exchangeable calcium and available silicate level in 1999 was 4.0 $cmol_c\;kg^{-1}$, 86 mg $kg^{-1}$, but had risen to 4.7 $cmol_c\;kg^{-1}$, 126 mg $kg^{-1}$ in 2007, respectively. The change of paddy soils quality index was increased gradually and increasement of silicate quality index was higher than other quality indicators.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.945-953
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• 2010

This study was conducted to evaluate the effect of swine liquid manure (SLM) on rice grown in Yeonggwang-gun in 2008. The treatments consisted of SLM and chemical fertilizer (CF) based on the recommended amount of nitrogen (11 kg N $10a^{-1}$). The Total N content of the SLM used was 2,881 mg $L^{-1}$. Plant height at the early stage of growth and tiller number were not significantly different between plots applied with swine liquid manure and those with chemical fertilizer in all areas. Plant height at the later stage of growth, lodging and yield were not significantly different between plots applied with swine liquid manure and those with chemical fertilizer in three areas (Baeksu, Gunnam, Beopseong). Plant height at the later stage of growth, as well as lodging were higher in SLM plots than in chemically fertilized plots in Yeonggwang and Yeomsan. However, grain yield was lower in SLM plots than in chemically fertilized plots in these areas. Soil organic matter content and exchangeable cations increased in the swine liquid manure applied plots. Moreover, heavy metal content did not increase in the plots treated with swine liquid manure. Further research to determine the suitable rate of swine liquid manure is needed to reduce lodging damage and to increase the yield and quality of rice.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.1040-1046
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• 2010

This research is composed of a series of survey of existing plants species by classifying biotope type of agro-ecosystem of Guksoo village area of Yangpyeong County, to collect and analyze basic data of vegetation analysis for indicators development of agro-ecosystem habitat quality. From the observation area, we found total 141 kinds of tracheophytes (53 Family 114 Genus 124 Species 16 Variety 1 Breed) and they are 3.36% of total Korean tracheophytes (4,191 kinds). Among those 141 tracheophytes, there are 23 kinds of naturalized plants (11 Family 20 Genus 20 Species 2 Variety) and they are 8.61% of total Korean naturalized plants (267 kinds). Among those 141 tracheophytes, they include 0.71% of pteridophyte, 0.71% of gymnosperm, 98.58% of angiosperm. So, most of them are angiosperm. When we classify them according to plant life form characteristics, dormant/diapause type plants include 45 species (31.91%) of annual plant (Th), 19 species (13.48%) of Th (w), 17species (12.06%) of hemicryptophyte (H). Regarding propagation type, as for the Radicoid form, there are 99 species (70.21%) of crumb structure plant, 13 species (9.22%) of $R_4$, 12 species (8.51%) of $R_{2.3}$ are the crumb structure does not make any connection on the ground or under ground. As for the Disseminule form of propagation type, there are 62 species (43.97%) of Gravity dispersal type $D_4$), 23 species (16.31%) of Wind dispersal type ($D_1$), 21 species (14.89%) of $D_{1.4}$. According to this survey of plant distribution rate by plant life form characteristics, we may acquire many knowledge about species composition of sociability, cluster's reaction against environmental elements, space usage and possible species competition in community. It may be very useful basic data for habitat preservation to keep and promote biological diversity.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.804-811
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• 2010

The lower portion of sloping paddy fields normally contains excessive moisture and the higher water table caused by the inflow of ground water from the upper part of the field resulting in non-uniform water content distribution. Four drainage methods namely Open Ditch, Vinyl Barrier, Pipe Drainage and Tube Bundle for multiple land use were installed within 1-m position from the lower edge of the upper embankment of sloping alluvial paddy fields. Knowledge of the spatial variability of soil water properties is of primary importance for management of agricultural lands. This study was conducted to evaluate the effect of drainage in the soil on spatial variability of soil water content using the geostatistical analysis. The soil water content was collected by a TDR (Time Domain Reflectometry) sensor after the installation of subsurface drainage on regular square grid of 80 m at 20 m paddy field located at Oesan-ri, Buk-myeon, Changwon-si in alluvial slopping paddy fields ($35^{\circ}22^{\prime}$ N, $128^{\circ}35^{\prime}$). In order to obtain the most accurate field information, the sampling grid was divided 3 m by 3 m unit mesh by four drainage types. The results showed that spatial variance of soil water content by subsurface drainage was reduced, though yield of soybean showed the same trends. Value of "sill" of soil water content with semivariogram was 9.7 in Pipe Drainage, 86.2 in Open Ditch, and 66.8 in Vinyl Barrier and 15.7 in Tube Bundle.