• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.11
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• pp.1145-1151
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• 2015

High pressure components of a gas turbine engine must operate for a long life under severe conditions in order to maximize the performance and minimize the maintenance cost. Enhanced cooling design, thermal barrier coating techniques, and nickel-base superalloys have been applied for overcoming them and furthermore, material modeling, finite element analysis, statistical techniques, and etc. in design stage have been utilized widely. This article aims to evaluate the effects on the low cycle fatigue life of the high pressure turbine nozzle caused by different turbine inlet temperature profiles and installation conditions and to investigate the most favorable operating condition to the turbine nozzle. To achieve it, the structural analysis, which utilized the results of conjugate heat transfer analysis as loading boundary conditions, was performed and its results were the input for the assessment of low cycle fatigue life at several critical zones.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.s02
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• pp.66-80
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• 1989

Salt injury in rice is caused mainly by the salinity in soil and in the irrigated water, and occasionaly by salinity delivered through typhoon from the sea. The salt concentration of rice plants increased with higher salinity in the soil of the rice growing. The climatic conditions, high temperature and solar radiation and dry conditions promote the salt absorption of rice plant in saline soil. The higher salt accumulation in the rice plant generally reduces the root activity and inhibits the absorption of minerals of rice plant, resulting the reduction of photosynthesis. The salt damages of rice plant, however, are different from different growth stage of rice plants as follows: 1. Germination of rice seed was slightly delayed up to 1.0％ of salt concentration and remarkably at 1. 5％, but none of rice seeds were germinated at 2.5％. This may be due to the delayed water uptake of rice seeds and the inhibition of enzyme activity, 2. It was enable to establish rice seedlings at seed bed by 0.2％ of salt concentration with some reduction of leaf elongation. The increasing of 0.3％ salt concentration caused to the seedling death with varietal differences, but most of seedlings were death at 0.4％ with no varietal differences. 3. Seedlings grown at the nursery over 0.1％ salt, gradually reduced in rooting activity after transplanting according to increasing the salt concentration from 0.1％ up to 0.3％ of paddy field. However, the seedlings grown in normal seed bed showed no difference in rooting between varieties up to 0.1％ but significantly different at 0.3％ between varieties, but greatly reduced at 0.5％ and died at last in paddy after transplanting. 4. At panicle initiation stage, rice plant delayed in heading by salt damage, at meiotic stage reduced in grains and its filling rate due to inhibition of glume and pollen developing, and salt damage at heading stage and till 3 weeks after heading caused to reduction of fertilization and ripening rate. In viewpoint of agricultural policy the overcoming strategy for salt injury is to secure sufficient water source. Irrigation and drainage systems as well as underground drainage is necessary to desalinize more effectively. This must be the most effective and positive way except cost. By cultural practice, growing the salt tolerant variety with high population could increase yield. The intermittent irrigation and fresh water flooding especially at transplanting and from panicle initiation to heading stage, the most sensitive to salt injury, is important to reduce the salt content in saline soil. During the off-cropping season, plough and rotavation with flooding followed by drainage, or submersion and drainage with groove could improve the desalinization. Increase of nitrogen fertilizer with more split application, and soil improvement by lime, organic matter and forign soil addition, could increase the rice yield. Shift of trans-planting is one of the way to escape from the salt injury.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.133-139
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• 2005

Resonant-Type Magnetometer(RM) using high permeability isotropic magnetic material is designed to implement Smart Digital Compass. Theoretically, the inductance L of a coil, winding on the magnetic core, is proportion to the change of permeability $\mu(H)$ and, the change values of L can be obtain as the change of frequency by simple Schmitt Trigger circuit. By the use of integrated circuit switch, the RM can be designed with simple circuit and it can provide overcoming the drift by temperature and the variation of operating points in $\mu(H)$ curve. The facts that Metglas 2705M is an optimum magnetic material and ship's permanent magnetism can be obtain from measured values of RM are also known in this study.

• Ocean and Polar Research
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• v.33 no.4
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• pp.447-455
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• 2011

Using results from an earth system model, the distribution of partial pressure of $CO_2$ ($pCO_2$) in surface seawater over the East China Sea is investigated. In this area $pCO_2$ shows minimum along the edge of the continental break along the path of the Taiwan-Tsushima Current System. Apparently modelled chlorophyll is also great along the current but the maximum of the chlorophyll and the minimum of $pCO_2$ do not coincide suggesting that the primary production is not the main cause of the $pCO_2$ minimum. As we move toward the Yellow Sea from the Kuroshio area the temperature decreases so that the $pCO_2$ becomes smaller. If we move further toward the Yellow Sea beyond the Taiwan-Tsushima Current System, alkalinity starts to drop substantially to intensify $pCO_2$ while overcoming the effect of decreasing temperature and salinity. Thus $pCO_2$ minimum occurs along the Taiwan-Tsushima Current System. Of course, the primary production lower $pCO_2$ during spring when it is high but the effect is local. Near the Yangtze river mouth and northeastern corner of the Yellow Sea the fresh water input is large enough and dissolved inorganic carbon (DIC) becomes low enough so that $pCO_2$ becomes lower again.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.688-697
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• 2014

In this study, electrode bonding technology needed for high density of rechargeable battery is studied, which is recently researched for electric vehicle, the small leisure vessel. For the alternative overcoming the limit of stacking amount able to be stacked by conventional ultrasonic welding, the low temperature bonding method, eligible for minimum of degeneration of chemical activator on the electrode surface which is generated by thermal effect as well as the increase of conductivity and tension strength caused by electrode bonding using filler metal, not using conventional direct heating on the electrode material method, is studied. Specifically to say, recently used more generally the ultrasonic welding and spot welding method are not usable for satisfying stable electric conductivity and bonding strength when much electrode is stacking bonded. If the electrical power is unreasonably increased for the welding, due to the effect of welding temperature, deformation of electrode and activating material degeneration are caused, and after the last packaging, decline of electrical output and generating heat cause to reduce stability of battery. Therefore, in this study, induction heating system bonding method using high frequency heating and differentiated electrode method using filler metal pre-treatment of hot dipping are introduced.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.5
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• pp.79-86
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• 2009

This research performed to analyze surplus solar energy, which is generated from a greenhouse during daytime, and to make the basic materials for designing thermal energy storage system for surplus solar energy. For this goal, it analyzed the surplus solar energy coming from two types of greenhouse. The results of this research are as per the below: In the case of 1-2W-type greenhouse, this research gave the same temperature and ventilation condition regardless of regions, but it was judged that the quantity of surplus solar energy could be greatly changed, depending on the energy consumed for the photosynthesis and evapotranspiration of crops in the greenhouse, on the heating temperature during daytime and night, on the existence/non-existence of a curtain and its warming effect, and on the ventilation temperature suitable for the overcoming of high temperature troubles or for the optimum cultivation temperature. In the case of a single-span greenhouse, there was a big difference in energy incoming and outgoing by month, but throughout seasons, 85.0 % of the total energy put into the greenhouse was solar energy and the energy input by heating was just 15.0 % of the total. 26.4 % of the total energy input for the greenhouse was used for photosynthesis and evapotranspiration of crops, and 44.2 % of the remaining 73.6 % went out in the form of radiant heat through the surface of the greenhouse. That is, 25.2 % of the total energy loss was just the surplus solar energy. 67.6 % of the total heating energy was concentrically used for 3 months from December to February next year, but the surplus solar energy during the same period was just 19.4 % of the total annual quantity so it was found that the given condition was more restrictive in directly converting the surplus heat into greenhouse heating. Under the disadvantageous circumstance of 3 months from December to February next year, it was possible to supplement 28 % (December) $\sim$ 85 % (February) of heating energy with surplus solar energy.

• Journal of the Korea Institute of Building Construction
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• v.10 no.4
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• pp.75-82
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• 2010

As structures become larger, taller, and more diverse, a high degree of technology and expertise are required in the construction industry. However, it has been becoming difficult to construct under severe conditions and to fulfill the high performance needs of structures due to a lack of skilled construction engineers. To compensate for these weak points, high-performance concrete and performance specifications have been developed. The application of reliable high-fluidity concrete, which is one of these efforts, is expected to be effective in terms of overcoming severe conditions, reducing the number of workers required, and shortening the construction period. In order to apply high fluidity concrete in the field, practical mock-up tests were carried out to estimate whether self-compaction concrete could satisfy constructability needs. From the results, it was verified that the multi-component high fluidity concrete has excellent flowability in practical structures. In addition, it was shown that the temperature distribution in the concrete due to hydration heat is satisfactory. As a result, it is judged that multi-component high fluidity concrete can be utilized as an effective building material for various structures, including structures related to the electric power industry.

• Journal of Food Hygiene and Safety
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• v.33 no.4
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• pp.229-239
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• 2018

Currently, in Korea, a dry food simulant has not been designated for the migration testing of paper and board, food contact materials (FCMs) being used in dry foods, and foods heated at ultra-high temperature. Considering the diverse usage of FCMs, in order to secure reliable and confident safety evaluation and to overcome the non-trade barrier tariff in worldwide trade, migration testing methods of what should be more clearly defined for securing and overcoming. This article delves into the available literature on the use of $Tenax^{(R)}$ as a simulant for dry foods as well as its suitability and limitations, and examines the feasibility of its introduction into Korean FCMs regulation. Most experimental studies using $Tenax^{(R)}$ showed overestimated migration values when used in real foods, which reflects the potential of $Tenax^{(R)}$ as a dry food simulant in a worst-case scenario. However, more studies are required to optimize migration testing using $Tenax^{(R)}$ by standardizing the solvent type and the extraction method for surrogates of various FCMs and foods, and to resolve the potential drawbacks in the use of $Tenax^{(R)}$.

• Journal of Bio-Environment Control
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• v.9 no.1
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• pp.1-10
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• 2000

This study was performed to find an efficient method to overcome extremely high temperature in greenhouses during summer season. The actual utilization of greenhouses during hot summer season showed that about 21.6％ of the investigated greenhouse farms were in fallow state, and most of greenhouse farms were cultivated under the very inferior environment. Thermal environment of greenhouses according to the evaporative cooling method and several assistant cooling methods such as ventilation, shading screen, roof sprinkling were examined. As the each assistant cooling method was used, about 74.8％, 25.9％, and 58.2％ of temperatures measured at intervals of ten minutes between ten and seventeen o'clock were above 35$^{\circ}C$. When shading screen and evaporative cooling system were operated, most greenhouse air temperatures were maintained below 35$^{\circ}C$, and showed a drop of 3.8~4.2$^{\circ}C$ as compared with naturally ventilated greenhouse.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.4
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• pp.370-377
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• 1989

Jerusalem artichoke (Helianthus tuberosus L.) as a biomass potential crop has several distinct advantages such as vigorous growth on poor land and high yield of carbohydrate. In this crop, seed dormancy has hampered the efforts of seed-propagration and to use them in breeding programs for improving jerusalem artichoke. Several seed treatments were tested to determine their effectiveness in overcoming the seed dormancy found in five collected varietes of jerusalem artichoke. The first results showed that the seed fertilities of five collected varieties ranged from 2.4％ to 14.7％ and the number of seed produced by one plant ranged from 88 to 1058. Germinability of seeds stored for 3 months at room temperature after harvest was almost 0％ and it was not improved by addition to the treatments of temperature, light and GA3, while germinability of seeds stored for 27 months at room temperature after harvest increased to 47.5％ in germination rate. But the removal and pin-pricking of seedcoat were very effective in breaking the seed dormancy, giving germination of 96.8％ and 82.3％, respectively. These results showed that the seed dormancy of jerusalem artichoke was induced by the seedcoat. Besides the treatment of seedcoat removal and seedcoat-pinpricking, the treatment of low and wet stratification was also effective in breaking the seed dormancy of jerusalem artichoke. Whole dormant seeds incubated for 70 days in low and wet condition germinated over 85％.