• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.133-140
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• 2016

The Ministry of Land, Infrastructure and Transport has introduced low-floor buses, which are convenient for passengers getting on and off the bus and for the handicapped. The standard bus model is 11 m long and uses compressed natural gas (CNG). However, this model has drawbacks in narrow rural road conditions such as those in farming and fishing villages and mountainous areas, as well as difficulty in refueling since CNG facilities are not readily available. In this study, running resistance values were obtained by coasting performance tests on actual roads using a Tata Daewoo LF-40 model with three different weight conditions: curb vehicle weight (CVW), half vehicle weight (HVW), and gross vehicle weight (GVW).The test methods include WHVC, NIER-06, and constant-speed driving at 60 km/h. These tests were used to measure the fuel economy of vehicles other than the target vehicles to obtain the combined fuel economy. The energy efficiency was highest in the case of CVW. In the WHVC mode, the fuel consumption rates of HVW and GVW were typically 3.5% and 12% higher than that of CVW, respectively. In constant-speed driving, the fuel efficiency of HVW was higher than that of CVW. Further research is required to analyze the exhaust gas data.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.57-57
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• 2022

In many areas of the world, salt damage and drought have had a negative impact on human survival due to a decrease in agricultural productivity. For instance, about 50% of agricultural land will be affected by salt damage by 2050. Biostimulants such as plant extracts can not only increase the nutrient utilization efficiency of plants, but also promote plant growth and increase resistance to abiotic or biotic stress. Therefore, the objective of this study was to determine how selected plant extracts might reduce levels of stress caused by drought and salt and to better understand the physiological response mechanisms of rice plants. In this study, we used Soybean leaves, Soybean stems and Allium tuberosum, Allium cepa, Hizikia fusiforme, and Gracilaria verrucosa extracts were used. These extracts had been used in previous studies and were found to be effective. The materials were dried in a dry oven at 50℃ for 5 days and ground using a blender. Each 50 g of materials was put in 1 L of distilled water, stirred for 24 hours, filtered using 4 layers of mirocloth, and then concentrated using a concentrator. Rice (cv. Hopumbyeo) seeds were immersed and germinated, and then sown in seedbeds filled with commercial soil. In drought experiments, three rice seedlings at 1 week after seeding was transplanted into 100 ml cups filled with commercial soils and grown until the 4-leaf stage. For this experiment, the soil weight in a cup was equalized, and water was allowed to become 100% saturated and then drained for 24 hours. Thereafter, plant extracts at 3% concentrations were applied to the soils. For NaCl treatments, rice plants at 17 days after seeding were treated with either 100 mM NaCl or plant extracts at 1%+ 100 mM NaCl combinations in the growth chamber. Leaf injury, relative water content, photosynthetic efficiency, and chlorophyll contents were measured at 3, 5, and 6 days after treatments. Shoot fresh weight of rice under drought conditions increased 28-37% in response to treatments of Soybean leaf, Soybean stem, Allium tuberosum, Allium cepa, Hizikia fusiforme, and Gracilaria verrucosa extracts at 3% when compared with control plants. Shoot fresh weight of rice subjected to 100 mM NaCl treatments also increased by 6-24% in response to Soybean leaf, Soybean stem, Allium tuberosum, Allium cepa, Hizikia fusiforme, and Gracilaria verrucosa extracts at 3% when compared with control plants. Compared to the control, rice plants treated with these six extracts and subjected to drought conditions had significantly higher relative water content, Fv/Fm, total chlorophyll and total carotenoids than control plants. With the exception of relative water contents, rice plants treated with the six extracts and subjected to salt stress (100 mM NaCl treatments) had significantly higher Fv/Fm, total chlorophyll and total carotenoids than control plants. However, the type of extract used did not produce significant difference in these parameters. Thus, all the plant extracts used in this study could mitigate drought and NaCl stresses and could also contribute substantially to sustainable crop production.

• Journal of the Korean Vacuum Society
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• v.21 no.3
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• pp.142-150
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• 2012

In this Study, Mo back electrode were deposited as the functions of various working pressure, deposition time and plasma per-treatment on sodalime glass (SLG) for application to CIGS thin film solar cell using by DC sputtering method, and were analyzed Mo change to $MoSe_2$ layer through selenization processes. And finally Mo back electrode characteristics were evaluated as application to CIGS device after Al/AZO/ZnO/CdS/CIGS/Mo/SLG fabrication. Mo films fabricated as a function of the working pressure from 1.3 to 4.9mTorr are that physical thickness changed to increase from 1.24 to 1.27 ${\mu}m$ and electrical characteristics of sheet resistance changed to increase from 0.195 to 0.242 ${\Omega}/sq$ as according to the higher working pressure. We could find out that Mo film have more dense in lower working pressure because positive Ar ions have higher energy in lower pressure when ions impact to Mo target, and have dominated (100) columnar structure without working pressure. Also Mo films fabricated as a function of the deposition time are that physical thickness changed to increase from 0.15 to 1.24 ${\mu}m$ and electrical characteristics of sheet resistance changed to decrease from 2.75 to 0.195 ${\Omega}/sq$ as according to the increasing of deposition time. This is reasonable because more thick metal film have better electrical characteristics. We investigated Mo change to $MoSe_2$ layer through selenization processes after Se/Mo/SLG fabrication as a function of the selenization time from 5 to 40 minutes. $MoSe_2$ thickness were changed to increase as according to the increasing of selenization time. We could find out that we have to control $MoSe_2$ thickness to get ohmic contact characteristics as controlling of proper selenization time. And we fabricated and evaluated CIGS thin film solar cell device as Al/AZO/ZnO/CdS/CIGS/Mo/SLG structures depend on Mo thickness 1.2 ${\mu}m$ and 0.6 ${\mu}m$. The efficiency of CIGS device with 0.6 ${\mu}m$ Mo thickness is batter as 9.46% because Na ion of SLG can move to CIGS layer more faster through thin Mo layer. The adhesion characteristics of Mo back electrode on SLG were improved better as plasma pre-treatment on SLG substrate before Mo deposition. And we could expect better efficiency of CIGS thin film solar cell as controlling of Mo thickness and $MoSe_2$ thickness depend on Na effect and selenization time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.54-63
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• 2018

In this study, the stability and economic feasibility of a MSE (Mechanically stability earth) wall with a pre-cast concrete pacing panel was investigated for a standard section of highway. Based on the design criteria, the MSE walls of the panel type were designed considering the load conditions of the highway, such as the dead load of the concrete pavement, traffic load, and impact load of the barrier. The length of the ribbed metal strip was arranged at 0.9H according to the height of the MSE walls. Because the length of the reinforcement was set to 0.9H according to the height of the MSE wall, the external stability governed by the shape of the reinforced soil was not affected by the height increase. The factor of safety (FOS) for the bearing capacity was decreased drastically due to the increase in self-weight according to the height of the MSE wall. As a result of examining the internal stability according to the cohesive gravity method, the FOS of pullout was increased and the FOS of fracture was decreased. As the height of the MSEW wall increases, the horizontal earth pressure acting as an active force and the vertical earth pressure acting as a resistance force are increased together, so that the FOS of the pullout is increased. Because the long-term allowable tensile force of the ribbed metal strip is constant, the FOS of the fracture is decreased by only an increase in the horizontal earth pressure according to the height. The panel type MSE wall was more economical than the block type at all heights. Compared to the concrete retaining wall, it has excellent economic efficiency at a height of 5.0 m or more.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.961-964
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• 2008

There are researches in progress on ensuring the safety of the high impact concrete in case of fire which is a current rising social problem and this research institute also developed PFB technology, the explosion preventing technology. PFB technology is to apply POSCO E&C Fire Board, a fireproof board, with an adhesive agent on the construction site, and this technology passed 3-hour fireproof test and this technology was proven from a previous research that the temperature of main root is maintained under $200^{\circ}C$. Therefore, tests on basic contents was performed in this research before the actual construction, with a full scale of wooden prototype to apply PFB technology to actual construction sites and the tests were done on the workability of fireproof board, the adhesive power, the resistance against imprint of wooden nail, the heat conductivity and etc. As the results of these tests, PFB technology was proven to have an excellent workability at a construction site and to be easy for processing and also, this technology was proven to have a great resisting power against imprint of wooden nail. Therefore, this research has confirmed that PFB technology has no problem to be applied on a construction site.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.6
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• pp.675-679
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• 2024

Wide bandgap (WBG) devices, especially SiC, are gaining traction as materials for high-power EV conversion devices due to their superior efficiency and switching capabilities compared to Si-based power devices. SiC allows for high power, high temperature, and high frequency applications because of its outstanding thermal conductivity, saturation velocity, and dielectric breakdown field. SiC-based MPS diodes combine the advantages of SiC-based SBDs and PiN diodes, allowing high-frequency switching operation with low leakage currents under high voltage conditions. However, MPS diodes exhibit snapback phenomena influenced by the P⁺ region's size, necessitating optimization. A TCAD simulation studied the impact of the P⁺ region's depth and width on MPS diode performance. Increasing the P⁺ width raised the On-specific resistance (R_on,sp) and lowered the maximum voltage during snapback (V_snap). Increasing the depth decreased both Breakdown voltage (BV) and V_snap. A trade-off between the semiconductor performance index BFOM and V_snap was identified, leading to optimized dimensions. The optimized MPS diode shows a low V_snap of about 3.89 V and a high BFOM of 1.72 GW·cm², highlighting its potential as a next-generation high-performance power conversion device.

• Journal of Life Science
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• v.34 no.10
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• pp.730-743
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• 2024

Industrial biotechnology leverages microorganisms such as Saccharomyces cerevisiae and Escherichia coli for sustainable production of chemicals, fuels, and pharmaceuticals. However, despite their potential, microbial production faces challenges due to environmental stressors, which impede efficiency and economic feasibility. While traditional genetic engineering offers solutions, it often fails to create robust strains for industrial conditions. Adaptive laboratory evolution (ALE) has emerged as a potent strategy to enhance microbial resilience by mimicking natural selection under controlled conditions. ALE has successfully improved tolerance to stressors such as toxic compounds, extreme pH, and high temperatures in various microorganisms. In yeasts, ALE has enhanced acetic acid and furfural tolerance, which is crucial for bioethanol production. Similarly, in E. coli, ALE has increased resistance to acid stress and improved production of succinic acid and L-serine. In lactic acid bacteria, ALE has boosted lactic acid production and strain stability under thermal and freeze-thaw stresses, benefiting both industrial and probiotic applications. Corynebacterium glutamicum has also shown significant improvements in growth rates, stress tolerance, and production capabilities through ALE. These advancements underline ALE's role in optimizing microbial strains for diverse industrial processes, making it a powerful tool in microbial biotechnology. This review highlights the latest applications and methods of ALE, emphasizing its impact on industrial microorganisms and potential for future research in sustainable bioproduction.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.7
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• pp.380-394
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• 2015

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

• Journal of Biosystems Engineering
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• v.5 no.1
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• pp.1-14
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• 1980

Threshing operation may be one of the most important processes in the paddy post-production system as far as the grain loss and labor requirement are concerned . head-feeding type threshers commercially available now in Korea originally were developed for threshing dry paddy in the range of 15 to 17 % in wet basis. However, threshing wet-paddy with the grain moisture content above 20 % has been strongly recommended, especially for new high-yielding Indica -type varieties ; (1) to reduce high grain loss incurred due to the handling operations, and (2) to prevent the quantitative and qualitative loss of milled -rice when unthreshed grains are rewetted due to the rainfall. The objective of this study were to investigate the adaptability of both a head-feeding type thresher and a throw-in type thresher to wet-paddy , and to find out the possiblilities of improving the components of these threshers threshing. Four varieties, Suweon 264 and Milyang 24 as Tongil sister line varieties, minehikari and Jinhueng as Japonica-type varieties, were used at the different levels of the moisture content of grains. Both the feed rate and the cylinder speed were varied for each material and each machine. The thresher output quality , composition of tailing return, and separating loss were analyzed from the sampels taken at each treatment. A separate experiment for measurement opf the power requirement of the head-feeding type thresher was also performed. The results are summarized as follows : 1. There was a difference in the thresher output quality between rice varieties. In case of wet-paddy threshing at 550 rpm , grains with branchlet and torn heads for the Suweon 264 were 12 % and 7 % of the total output in weight, respectively, and for the Minehikari 4.5 % and 2 % respectively. In case of dry paddy threshing , those for the Suweon 264 were 8 % and 5% , and for the Minehikari 4% and 1% respectively. However, those for the Milyang 23 , which is highly susceptable to shattering, were much lower with 1 % and 0.5% respectively, regardless of the moisture content of the paddy. Therefore, it is desirable to breed rice varieties of the same physical properties as well as to improve a thresher adaptable to all the varieties. Torn heads, which increased with the moisture content of rall the varieties except the Milyang 23 , decreased as the cylinder speed increased, but grains with branchlet didnt decrease. The damaged kernels increased with the cylinder speed. 3. The thresher output quality was not affected much by the feed rate. But grains with branchlet and torn heads increased slightly with the feed rate for the head-feeding type thresher since higher resistance lowered at the cylinder speed. 4. In order to reduce grains with branchlet and torn heads in wet-paddy threshing , it is desirable to improve the head-feeding type thresher by developing a new type of cylinder which to not give excess impact on kernels or a concave which has differenct sizes of holes at different locations along the cylinder. 5. For the head-feeding type thresher, there was a difference in separating loss between the varieties. At the cylinder speed of 600 rpm the separating losses for the Minehikari and the Suweon 264 were 1.2% and 0.6% respectively. The separating loss of the head-feeding type thresher was not affected by the moisture content of paddy while that of the Mini-aged thresher increased with the moisture content. 6. From the analysis of the tailings return , to appeared that the tailings return mechanism didn't function properly because lots of single grains and rubbishes were unnecessarily returned. 7. Adding a vibrating sieve to the head-feeding type thresher could increase the efficiency of separation. Consequently , the tailing return mechanism would function properly since unnecessary return could be educed greatly. 8. The power required for the head-feeding type thresher was not affected by the moisture content of paddy, but the average power increased linearly with the feed rate. The power also increased with the cylinder speed.