• Korean Journal of Food Science and Technology
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• v.45 no.5
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• pp.571-577
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• 2013

Our aim was to ferment soymilk using lactic acid bacteria that showed protease activity and to optimize the condition for fermentation. In total, 108 strains of protease-producing lactic acid bacteria were isolated from various fermented foods such as kimchi and jeotgal, and among them, 29 strains displaying the highest protease activity were selected for further study. From these 29 strains, strain MK1, whose protease activity was 126 $mU/mL{\cdot}min$, was selected as the optimal fermentation strain owing to its high ability to digest soymilk protein. It was henceforth labeled as Lactobacillus paracasei MK1. The optimum conditions for the fermentation of soymilk by using L. paracasei MK1 were determined to be as follows: 30 h of fermentation time at a temperature of $30^{\circ}C$, and at a pH of 6.0 in the initial growth medium.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.3
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• pp.221-230
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• 2014

In order to restore an ecologically damaged river, freshwater fish which inhabit at the target aquatic ecosystem have a great applicability as one of the essential indicators. Although the informations about the habitat conditions of freshwater fish are key elements reflecting biological, physical, and chemical properties of the aquatic environment, because of the lack of preceding related research and insufficient database with scattered data, they have not been applied effectively for the ecological river restoration projects in Korea. To cope with these problems, based on the nation-wide detailed investigation for domestic freshwater fish habitat conditions, we have selected 70 species considering the possibility for the candidates of flagship species, constructed a database for their population, physical, and chemical habitat properties, and suggested its application methodology for the river restoration projects. In particular, the utilization of the database has been enhanced by the additional statistical analysis to present their resistance and optimum ranges for physical, and chemical habitat properties respectively. It is expected that the database constructed in this study can be utilized for the calculation and evaluation of the appropriate ecological flow rate and target water quality for the selected flagship species (fish), and the basic data for the restoration of river environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.11
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• pp.879-894
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• 2013

Recently, due to a explosive growth in the mobile Internet traffic, the problem of excessive data traffic handling on core network and thus scalability problem have been magnified in 3GPP LTE/SAE networks. Current LTE/SAE network based on the central P-GW (PDN Gateway) used as mobility anchor cannot deal with such demand for exponentially increasing mobile Internet traffic. In this paper, we propose a new LTE/SAE network architecture supporting distributed P-GWs and corresponding distributed mobility management to solve these problems. For this, in addition to the deployment of such distributed P-GWs, we propose a dynamic and distributed mobility management by distributing MMEs (Mobility Management Entities) which dynamically manages the location information of a UE's PDN connection, and also propose a handover procedure of such PDN connections by using the proposed distributed P-GWs and MMEs. The performance of the proposed dynamic and distributed LTE/SAE network system is compared with the current LTE/SAE network system in terms of handover latency and network throughput.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.4
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• pp.65-71
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• 2013

Wind shear means the variation of wind speed according to the height. Wind shear is the important factor affecting the energy production of wind turbines. Power Law is used to extrapolate wind speed data. Normally, a Power Law exponent of 0.143 is used and this is referred to as the 1/7th Power Law. The Power Law exponent is affected by atmospheric stability and surface roughness of the site. Thus, it is necessary to calculate the Power Law exponent of the site exactly for an accurate estimation of wind energy. In this study, wind resources were measured at the three Met-masts which were located in the coastal area of northeastern Jeju Island. The Power Law exponents of the sites were calculated and proposed using measured data. They were 0.141 at Handong, 0.138 at Pyeongdae, and 0.1254 at Udo. We compared annual energy productions which are calculated using a Power Law exponent of 0.143, the proposed value of the Power Law exponents for each site, and the measured data. As a result, the cases of calculating using the proposed values were more similar to the cases using the measured data than the cases using the 0.143 value. Finally, we found that the propsed values of the Power Law exponent are available to more accurately estimate wind resources.

• Journal of the Korea Concrete Institute
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• v.26 no.1
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• pp.87-95
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• 2014

Experimental investigation on the structural behavior of steel fiber-reinforced ultra high performance concrete (UHPC) beams subjected to torsion are presented. Six tests carried out on square beams under torsional moment are presented. The experimental parameters were the volume fraction of the fibers and closed-stirrup ratio. The volume fraction of the fibers was 1.0% and 2.0%. The closed-stirrup ratio was 0, 0.35%, and 0.70%. The test results indicated that ultimate torsional strength increased with increasing fiber volume, and that ultimate torsional strength also increased with increasing the closed-stirrup ratio. In addition, predictive equations for evaluating the ultimate torsional strength of UHPC beams were proposed. The comparison between computed values and the experimentally observed values was shown to validate the proposed analytical equations. It was found that predictions by using proposed equation provides good agreement with test results of UHPC beams.

• Current Research on Agriculture and Life Sciences
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• v.18
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• pp.53-60
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• 2000

Seedling characteristics of rice sowed at different sowing date in an automatic facility were studied at different days after sowing (DAS). The objective was to determine the optimum sowing date and age of rice seedlings at three locations in the Kyongbuk Province of Korea viz, Andong, Euisung and Kyongsan. Heigbt and shoot dry weight of rice seedlings increased from 10 to 20 DAS and with a delay in sowing time from April to June. In these intervals shoot dry weight-height ratio decreased. For rice seeded in the last ten days of April, optimum seedling characteristics were attained between 15 to 20 DAS at Andong and Euisong and 15 DAS at Kyongsan. At the three locations, 10-day-seedlings exhibited superior characteristics to 15- and 20-day-seedlings for rice seeded in May and June. Rice seedlings of different ages were transplanted at a paddy field to determine the effect of seedling age on yield potential. The mean yield of 10-day-seedlings was 5% higher than that of 35-day-seedlings raised by the conventional method. The yield of 20-day-seedlings was 9% lower than that of 35-day-seedlings. Varietal differences in seedling characteristics of 13 rice cultivars were evaluated for the seedlings seeded in the automatic facility on June. Ten-day old seedlings ranged in height from 13.3 to 17.5 cm and shoot dry weight from 7.7 to 9.4 mg. Two cultivars, Daesanbyeo and Hwayeongbyeo, exhibited superior seedling traits compared to the remaining 11 cultivars and were, therefore, better adapted to the automatic seedling-raising facility.

• Current Research on Agriculture and Life Sciences
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• v.24
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• pp.43-47
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• 2006

The soils of plastic film houses in which intensive cultivation takes place suffer from the serious problems such as severe salinity and accumulation of heavy metals etc. The objective of this research was to examine the change in soil properties with repeated cucumber cultivation under plastic film house at Gunwi-Gun area. The soils were classified mainly to Danbuk and SinJung series. Clay content is lower in the soils of plastic film house than in the field soil. Available $P_2O_5$ and exchangeable cations were accumulated at the level higher than the optimum range. The content of extractable heavy metals were higher in the soils of plastic film house than in those of the field. For optimum yield, much attention should be paied to the management of soils by the pre-soil survey.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.297-304
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• 2013

Due to its excessive $CO_2$ emissions, road transport sector becomes a target for emission reduction strategies. Although precise and reliable emissions inventories are necessary for evaluating plans and strategies, developing the region-wide inventory is a difficult task mainly because of a lack of data including travel patterns and modal volumes in the reginonal context. Most existing inventory methodologies employ fuel sale data within the target region, which ignores actual regional traffic patterns and thus not suited to its geographical context. To overcome these problems, this study develops region-wide $CO_2$ emissions inventory methodology by utilizing the Korea Transport DB (KTDB). KTDB provides a number of useful information and data, such as road network with which one can identify in and out trips over the entire region, traffic volumes of various modes, distance of travel, travel speed and so on. A model of equations that allow the computation of volume of $CO_2$ emitting from the road transport activities within the target region is developed. Using the model, numerical analyses are performed for the case of Busan Metropolitan City to demonstrate the applicability of the developed model. This study is indeed exploratory in the sense that using the existing data, it develops the $CO_2$ emissions inventory methodology which can produce better results than those from conventional fuel sales methodology. This study also suggests further reresarch directions to develop more refined methodologies in region-wide basis.

• Spatial Information Research
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• v.20 no.2
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• pp.25-34
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• 2012

Air quality in Daegu area is lower compared to many other cities, since Daegu is a basin surrounded by mountains. Accordingly, the present study investigated the location of carbon monoxide(CO) monitoring stations for systematic CO pollution management on the basis of the CO emission distribution in Daegu area. In order to achieve this purpose, the location of CO monitoring stations, which can be used for the establishment of CO management, were assessed. Emission map in Daegu area was prepared using numerical map and Clean Air Policy Support System(CAPSS) data supplied by the M inistry of Environment. Average emissions were estimated by dividing emission sources into four subgroups(roadway, apartment, industry, and municipal incineration facility) according to legal division. The CO emission intensities were subdivided into 10, which a high number represents a high emission intensity, and the current monitoring stations were evaluated for the determination of their steps in CO emission intensities. As a result, additional installation of monitoring stations were suggested for the high CO emission areas rather than the low CO emission areas. A systematic CO management strategy would be established by the supplying various principle CO data when the CO monitoring stations are additionally installed at Kukwudong and other six sites on the basis of analyses of data obtained from 1999 to 2007.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.265-266
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• 2012

의료용 X-ray의 발전에 따라, 영상의 Digital화가 필요하게 되었다. Digital 영상 구현을 위해 다양한 형태의 영상 검출기가 개발되었다. 진단 영상의 조건으로는 구현 시간이 빠르고 해상도가 높아야 한다. 조건에 부합하는 Flat panel 형태의 직접방식과 간접방식 검출기의 개발이 주로 이루어졌으며, X-ray 검출 효율이 높고 공간 분해능이 높은 직접 방식의 검출기에 대한 연구가 활발히 진행되고 있다. 기존 직접방식의 X-ray 검출물질로는 A-Se이 이용되었다. 하지만 A-Se의 경우 낮은 원자번호로 인해 X-ray에 대한효율이 낮으며, 제조 공정과 수율의 문제로 인해 대체 물질의 개발과 공정의 개선이 필요하다. 선행 연구를 통해 X-ray 검출물질의 전기적 특성을 파악을 통해 대체 물질로서 가능성을 알아보았다. 본 연구에서는 기존에 제작된 X-ray 검출물질의 상부전극 증착 물질과 증착법 선정에 대한 연구이다. 선행 연구를 통해 선정된 X-ray 검출물질은 HgI2이다. 상, 하부 전극 선택에 있어 HgI2의 일함수 값(4.15eV)을 고려하여 그와 비슷한 일함수 값을 가진 물질로 전기적 장벽을 제거하여야 한다. 따라서, ITO (일함수 4.45eV)와 Au (일함수 5.1eV)을 선택하였다. ITO의 증착으로 이용된 방법으로는 on-axis 형태의 magnetron plasma sputtering을 이용하였으며, Au의 증착으로 이용된 방법은 Thermal evaporation deposition을 이용하였다. plasma sputtering에 이용된 타겟은 In2O3;SnO2 (조성비:90:10wt%)를 사용하였으며, Chamber의 크기는 넓이 456 ${\phi}cm^2$ 높이 25 cm이며, 로 target과 기판과의 거리는 15cm이다. plasma발생에 필요한 가스로는 Ar과 O2를 이용하였다. 고 진공 환경 조성에 이용된 장비로는 Rotary pump와 Turbo molecular pump이다. plasma 발생 전 진공도는 $3.2{\times}10^{-5}$ Torr, 발생 후 진공도는 $5.1{\times}10^{-5}$ Torr이다. plasma 환경이 조성된 후 증착 시간은 1분 30초이다. Au는 순도 99.999%를 이용하였으며, 이용된 금은 1회 증착에 0.3 g을 이용하였다. Chamber의 넓이 1,444 ${\phi}cm^2$이며, 높이 40 cm, boat와 기판과의 거리는 25 cm이다. 고 진공 환경 조성에 이용된 장비로는 Rotary pump와 diffusion pump를 이용하였다. Au의 승화 전 진공도는 $2.4{\times}10^{-5}$ Torr 증착 시 진공도는 $4.2{\times}10^{-5}$ Torr이며, Boat에 가해준 전압, 전류는 0.97 V, 47 A이며, 증착 시간은 1분 30초이다. 광도전체 층에 각각 증착된 전극의 저항을 통해 증착상태를 판단하였다. DMM (Digital Multimeter)로 1 cm 간격으로 측정된 표면의 저항은 ITO 약 $8{\Omega}$, Au 약 $3{\Omega}$으로 전극으로서 이용이 가능한 상태이다. Au와 ITO가 증착된 HgI2 시편의 전기적 특성은 기존에 이용된 X-ray 변환물질의 성능보다 우수하였다. 하지만 Au와 ITO가 각각 증착된 시편의 전기적 특성은 큰 차이를 보이지 않았다. ITO의 경우 진공 상태에서 이용되는 Gas가 이용되며, Plasma 환경 조성 유지가 어려운 점이 있다. Au전극은 증착 환경 조성이 쉽지만, 전극 물질 이용효율이 떨어지는 단점이 있다. 본 연구를 통해 X-ray 변환물질인 HgI2의 전극물질로 Au와 ITO의 이용가능성을 알아보았다. 두 전극으로 제작된 검출기의 성능은 큰 차이 없이 우수하였고, 전기적 장벽 상태가 낮아 높은 검출 효율을 보였다. 상대적으로 Au 전극의 공정이 간단하고 수율이 높다. 하지만 Au Source의 이용 효율이 떨어지는 단점이 있다. 본 연구의 결과를 통해 공정상의 유리함과 Source의 이용효율을 고려한 분석에 대한 연구가 필요할 것으로 사료된다.