• Journal of Advanced Marine Engineering and Technology
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• v.40 no.3
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• pp.157-164
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• 2016

In this study, researchers performed preliminary design and numerical analysis for a pilot-scale helium heating system intended to support full-scale construction for a sulfur-iodine (SI) cycle. The helium heat exchanger used a liquefied petroleum gas (LPG) combustor. Exhaust gas velocity at the heat exchanger outlet was approximately 40 m/s based on computational thermal and flow analysis. The maximum gas temperature was reached with six baffles in the design; lower gas temperatures were observed with four baffles. The amount of heat transfer was also higher with six baffles. Installation of additional baffles may reduce fuel costs because of the reduced LPG exhausted to the heat exchanger. However, additional baffles may also increase the pressure difference between the exchanger's inlet and outlet. Therefore, it is important to find the optimum number of baffles. Structural analysis, followed by thermal and flow analysis, indicated a 3.86 mm thermal expansion at the middle of the shell and tube type heat exchanger when both ends were supported. Structural analysis conditions included a helium flow rate of 3.729 mol/s and a helium outlet temperature of $910^{\circ}C$. An exhaust gas temperature of $1300^{\circ}C$ and an exhaust gas rate of 52 g/s were confirmed to achieve the helium outlet temperature of $910^{\circ}C$ with an exchanger inlet temperature of $135^{\circ}C$ in an LPG-fueled helium heating system.

• Journal of Korean Society of Disaster and Security
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• v.9 no.2
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• pp.63-75
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• 2016

For safe water supply, residual chlorine has to be maintained in tap-water above a certain level from drinking water treatment plants to the final tap-water end-point. However, according to the current literature, approximately 30-60% of residual chlorine is being lost during the whole water supply pathways. The losses of residual chlorine may have been attributed to the current tendency for water supply managers to reduce chlorine dosage in drinking water treatment plants, aqueous phase decomposition of residual chlorine in supply pipes, accelerated chlorine decomposition at a high temperature during summer, leakage or losses of residual chlorine from old water supply pipes, and disappearances of residual chlorine in water storage tanks. Because of these, it is difficult to rule out the possibility that residual chlorine concentrations become lower than a regulatory level. In addition, it is concerned that the regulatory satisfaction of residual chlorine in water storage tanks can not always be guaranteed by using the current design method in which only storage capacity and/or hydraulic retention time are simply used as design factors, without considering other physico-chemical processes involved in chlorine disappearances in water storage tank. To circumvent the limitations of the current design method, mathematical models for aqueous chlorine decomposition, sorption of chlorine into wall surface, and mass-transfer into air-phase via evaporation were selected from literature, and residual chlorine reduction behavior in water storage tanks was numerically simulated. The model simulation revealed that the major factors influencing residual chlorine disappearances in water storage tanks are the water quality (organic pollutant concentration) of tap-water entering into a storage tank, the hydraulic dispersion developed by inflow of tap-water into a water storage tank, and sorption capacity onto the wall of a water storage tank. The findings from his work provide useful information in developing novel design and technology for minimizing residual chlorine disappearances in water storage tanks.

• KDI Journal of Economic Policy
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• v.13 no.1
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• pp.115-134
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• 1991

The role of pension plans in the macroeconomy has been a subject of much interest for some years. It has come to be recognized that pension plans may alter basic macroeconomic behavior patterns. The net effects on both savings and labor supply are thus matters for speculation. The aim of the present paper is to provide quantitative results which may be helpful in attaching orders of magnitude to some of the possible effects. We are not concerned with the providing empirical evidence relating to actual behavior, but rather with deriving the macroeconomic implications for a alternative possibilities. The pension plan interacts with the economy and the population in a number of ways. Demographic variables may thus affect both the economic burden of a national pension plan and the ability of the economy to sustain the burden. The tax transfer process associated with the pension plan may have implications for national patterns of saving and consumption. The existence of a pension plan may have implications also for the size of the labor force, inasmuch as labor force participation rates may be affected. Changes in technology and the associated changes in average productivity levels bear directly on the size of the national income, and hence on the pension contribution base. The vehicle for the analysis is a hypothetical but broadly realistic simulation model of an economic- demographic system into which is inserted a national pension plan. All income, expenditure, and related aggregates are in real terms. The economy is basically neoclassical; full employment is assumed, output is generated by a Cobb-Douglas production process, and factors receive their marginal products. The model was designed for use in computer simulation experiments. The simulation results suggest a number of general conclusions. These may be summarized as follows; - The introduction of a national pension plan (funded system) tends to increase the rate of economic growth until cost exceeds revenue. - A scheme with full wage indexing is more expensive than one in which pensions are merely price indexed. - The rate of technical progress is not a critical element in determining the economic burden of the pension scheme. - Raising the rate of benefits affects its economic burden, and raising the age of eligibility may decrease the burden substantially. - The level of fertility is an element in determining the long-run burden. A sustained low fertility rate increases the proportion of the aged in total population and increases the burden of the pension plan. High fertility has inverse effects.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.345-359
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• 2002

The purpose of the study was to provide the fundamental data to instruct athletes through the analysis athletes' movement in javelin. Three athletes in the level of national representative were participated in this study. The study analyzed kinematic variables(lead foot and releasing javelin) through 3-D analysis and obtained the following results. 1. During withdrawal, it is important to maintain of running horizontal velocity. 2. It was showed that throng average height was $84{\pm}3.3%$ and javelin adequative degree, Among the athletes, $S_2$ who had the best record was released the javelin with the fast velocity, but throw the javelin with the less releasing velocity. 3. $S_2$ released after lead foot were completely landed and therefore it is no problem in a kinematic aspect. However, $S_1$ angle was too small. it caused increase of release velocity to be prevented. 4. $S_2$ showing the best result indicated shorter in duration time. Generally, the shorter duration time in release phase showed the longer release distance. Especially $S_1$ and $S_3$ showing the worse result indicated the longer duration time in preparatory phase, causing the breakup of force. Therefore to improve the record, it should be decreased the duration time in preparatory phase. 5. Compared with $S_1$ and $S_3$, $S_2$ showing the best record indicated the higher velocity in center of mass, trunk, upper arm, lower arm and hand That is the higher velocity of upper arm at release leaded the better velocity transfer from upper arm to following lower arm and hand, these action should be considered to be helpful of better record. According to the above conclusion, when the athletic leaders cauch athletes, they should focus on maintaining knee angle, upper body and hip angle in a previous stage of release and throwing angle, throwing height, throwing velocity in a release stage.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.24-30
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• 2011

BACKGROUND: High input to the arable land is contributed to increasing productivity with causing the global environmental problems at the same time. Rapeseed cultivation has been forced to reassess its positive point for utilization of winter fallow field. The Objective of this study was performed to assess the environmental impact of rapeseed cultivation with double-cropping system in paddy rice on Yeonggwang district using life cycle assessment technique. METHODS AND RESULTS: For assessing each stage of rapeseed cultivation, it was collected raw data for input materials as fertilizer and pesticide and energy consumption rate by analyzing the type of agricultural machinery and working hours by 1 ton rapeseed as functional unit. Environmental impacts were evaluated by using Eco-indicator 95 method for 8 impact categories. It was estimated that 216 kg $CO_2$-eq. for greenhouse gas, 3.98E-05 kg CFC-11-eq. for ozone lazer depletion, 1.78 kg SO2-eq. for acidification, 0.28 kg $PO_4$-eq. for eutrophication, 5.23E-03 kg Pb-eq. for heavy metals, 2.51E-05 kg B(a)p-eq. for carcinogens, 1.24 kg SPM-eq. for smog and 6,460 MJ LHV for energy resource are potentially emitted to produce 1 ton rapeseed during its whole cultivation period, respectively. It was considered that 90% of these potential came from chemical fertilizer. For the sensitivity analysis, by increasing the productivity of rapeseed by 1 ton per ha, potential environmental loading was reduced at 22%. CONCLUSION(s): Fertilization affected most dominantly to the environmental burden, originated from the preuse stage, i.e. fertilizer manufacturing and transporting. It should be included and assessed an indirect emission, which is not directly emitted from agricultural activities. Recycling resource in agriculture with reducing chemical fertilizer and breeding the high productive variety might be contribute to reduce the environmental loading for the rapeseed cultivation.

• Korean Journal of Environmental Agriculture
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• v.29 no.2
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• pp.206-213
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• 2010

The aim of this study was to provide basic informations for restoring a habitat of Nannophy pygmaea Rambur. Environments and flora of the habitats were investigated in Youngdong, Sanbuk, and Nongam South Korea. The habitats were abandoned paddy fields with tree-unshaded space and with the water depths of about 2 - 10 cm all the year round. The water quality was recorded 5.44 - 7.33 in pH, 0.017 - 0.480 dS/m in EC, 1.34 - 4.94 mg/L in T-N and 0.06 - 0.46 mg/L in T-P. The pH and EC showed a wide range values, and T-N and T-P showed a high values comparatively. This result implies that a water quality does not important as the condition for a habitat of the species. A total of 86 vascular plant taxa belonging to 35 families, 60 genera, 67 species, 2 subspecies, 14 varieties and 3 forma were recognized in the habitats. Twenty two species (25.6%) overlapped among the habitats; Equisetum arvense, Salix koreensis, Persicaria thunbergii, Stellaria alsine var. undulata, Hypericum laxum, Kummerowia striata, Epilobium pyrricholophum, Oenanthe javanica, Mosla dianthera, Utricularia vulgaris var. japonica, Plantago asiatica, Eupatorium lindleyanum, Juncus diastrophanthus, J. effusus var. decipiens, J. papillosus, Aneilema keisak, Alopecurus aequalis, Arthraxon hispidus, Carex dickinsii, Cyperus sanguinolentus, Eleocharis acicularis for. longiseta and E. congesta. Biological type was determined to be HH-R5-D4-e(t) type; HH 39 taxa (45.3%), R5 42 taxa (48.8%), D4 59 taxa (68.6%) and e (or t) 23 taxa (26.7%).

• Analytical Science and Technology
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• v.24 no.2
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• pp.150-157
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• 2011

Aflatoxins are secondary metabolites of the molds of Aspergillus flavus and Aspergillus parasiticus. They are highly carcinogenic compounds and can affect a wide range of vegetable commodities such as cereals (especially corn), nuts, peanuts, fruits and oil seeds, in the field and during storage. In fact, oilseeds are often stored for weeks in conditions that promote the mould growth, and the possible consequent presence of aflatoxins in oilseeds can lead to their transfer in oil. In addition, aflatoxins can be found as a natural contaminant in multi-cereals and beans making baby food for infants and young-children. The objective of this study was to validate the liquid extraction method or develop an analytical method for edible oil and infant-children foods. Therefore, this study developed condition of extract for aflatoxins ($B_1$, $B_2$, $G_1$ and $G_2$) in edible oil using a high performance liquid chromatography with florescence detector (HPLC/FLD). Aflatoxins were extracted from edible oil samples by means of MSPD (Matrix solid phased dispersion), utilizing $C_{18}$ as dispersing material and purified by using immunoaffinity column. The gression line coefficients were above 0.999. The recoveries for aflatoxins ranged from 85.9 to 93.0%, and relative standard deviations were below 5.7%. The new developed method of aflatoxins effectively enhanced recoveries by using MSPD-Immunoaffinity column compared with liquid extraction. The analytical method for liquid extraction of aflatoxin was appropriate for infant-children food. Reviewing the current method, the recoveries of aflatoxins ($B_1$, $B_2$, $G_1$ and $G_2$) were 89.5~92.3%.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.253-261
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• 2005

Catalytic wet oxidation of ppm levels of trichloroethylene (TCE) in water has been conducted using $TiO_2$-supported cobalt oxides at a given temperature and weight hourly space velocity. 5% $CoO_x/TiO_2$ might be the most promising catalyst for the wet oxidation at $36^{\circ}C$ although it exhibited a transient behavior in time on-stream activity. Not only could the bare support be inactive for the wet decomposition reaction, but no TCE removal also occurred by the process of adsorption on $TiO_2$ surface. The catalytic activity was independent of all particle sizes used, thereby representing no mass transfer limitation in intraparticle diffusion. Characterization of the $CoO_x$ catalyst by acquiring XPS spectra of both fresh and used Co surfaces gave different surface spectral features of each $CoO_x$. Co $2p_{3/2}$ binding energy of Co species exposed predominantly onto the outermost surface of the fresh catalyst appeared at 781.3 eV, which is very similar to the chemical states of $CoTiO_x$ such as $Co_2TiO_4$ and $CoTiO_3$. The spent catalyst possessed a 780.3 eV main peak with a satellite structure at 795.8 eV. Based on XPS spectra of reference Co compound, the TCE-exposed Co surfaces could be assigned to be in the form of mainly $Co_3O_4$. XRD measurements indicated that the phase structure of Co species in 5% $CoO_x/TiO_2$ catalyst even before reaction is quite comparable to the diffraction lines of external $Co_3O_4$ standard. A model structure of $CoO_x$ present on titania surfaces would be $Co_3O_4$, encapsulated in thin-film $CoTiO_x$ species consisting of $Co_2TiO_4$ and $CoTiO_3$, which may be active for the decomposition of TCE in a flow of water.

• Journal of Environmental Policy
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• v.11 no.4
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• pp.39-57
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• 2012

Analysis of the economic impact on Korean bioindustry companies was approached after Korea access to the Nagoya Protocol on Access to Genetic Resources and the Fair and Equitable Sharing of Benefits Arising from their Utilization to the Convention on Biological Diversity (hereinafter 'the Protocol') enters into force. Cost analysis of the economic impact is based on the size of bioindustry market, dependency ratio on genetic resources abroad, ABS (Access and Benefit Sharing) ratio for royalty ratio. Korean bioindustry companies would have had to pay extra ABS cost around 1.3-6.0 billion won for using genetic resources abroad, if the Protocol had entered into force in 2009. And this cost is estimated to be around 13.6 - 63.9 billion won in 2015. All ABS costs account only about less than 0.01% of total Korean bioindustry volume of target years. These show us that joining the Protocol will not significantly impact the bioindustry market in Korea. If the Protocol enters into force, genetic resources users have to pay PIC (Prior Informed Consent) and MAT (Mutually Agreed Terms) cost before accessing the genetic resources outside of their country, regardless of the accession status of the country. This ABS costs and terms on provided genetic resources will be determined by compliance between genetic resources users and providers. As a genetic resources provider, Korean bioindustry companies will have advantage over technology transfer agreements, royalties, licensing agreements, and taxes on profits from patents including traditional knowledge. Also, Korean bioindustry companies are expected to get various socio-economic benefits such as patent litigation and regulatory proceedings as a genetic resources provider. Considering the advantages and disadvantages of the Protocol that Korean bioindustry companies will face together, the socio-economic impact of the Nagoya Protocol on Korean bioindustry companies is negligible regardless of the accession status of Korea to the Nagoya Protocol.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.100-112
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• 2005

Soil temperature was measured from the surface to 40 cm depth at three stations with different heights in tidal flat of Gomso Bay, west coast of Korea, for one month in every season 2004 to examine the thermal structure and the variation. Mean temperature in surface layer was higher in summer and lower in winter than in lower layer, reflecting the seasonal variation of vertically propagating structure of temperature by heating and cooling from the tidal flat surface. Standard deviation of temperature decreased from the surface to lower layer. Periodic variations of solar radiation energy and tide mainly caused short term variation of soil temperature, which was also intermittently influenced by precipitation and wind. Time series analysis showed the power spectral energy peaks at the periods of 24, 12 and 8 hours, and the strongest peak appeared at 24 hour period. These peaks can be interpreted as temperature waves forced by variations of solar radiation, diurnal tide and interaction of both variations, respectively. EOF analysis showed that the first and the second modes resolved 96% of variation of vertical temperature structure. The first mode was interpreted as the heating antl cooling from tidal flat surface and the second mode as the effect of phase lag produced by temperature wave propagation in the soil. The phase of heat transfer by 24 hour period wave, analyzed by cross spectrum, showed that mean phase difference of the temperature wave increased almost linearly with the soil depth. The time lags by the phase difference from surface to 10, 20 and 40cm were 3.2,6.5 and 9.8 hours, respectively. Vertical thermal diffusivity of temperature wave of 24 hour period was estimated using one dimensional thermal diffusion model. Average diffusivity over the soil depths and seasons resulted in $0.70{\times}10^{-6}m^2/s$ at the middle station and $0.57{\times}10^{-6}m^2/s$ at the lowest station. The depth-averaged diffusivity was large in spring and small in summer and the seasonal mean diffusivity vertically increased from 2 cm to 10 cm and decreased from 10 cm to 40 cm. Thermal propagation speeds were estimated by $8.75{\times}10^{-4}cm/s,\;3.8{\times}10{-4}cm/s,\;and\;1.7{\times}10^{-4}cm/s$ from 2 cm to 10 cm, 20 cm and 40 cm, respectively, indicating the speed reduction with depth increasing from the surface.