• Korean Journal of Agricultural Science
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• v.45 no.2
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• pp.290-297
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• 2018

Electric drive technology is continually advanced to improve fuel efficiency in the automobile industry. It could improve the fuel efficiency of automobiles by 50% as well as agricultural machinery. The purpose of this study was to measure and analyze the power and current of an electric transplanter based on the planting distances during field operations. The electric transplanter was constructed by mounting the major components of a motor drive system onto a transplanter. The electric transplanter had a 3 kW motor power, and the major components included an inverter, battery, and a battery management system (BMS). The field tests were conducted by travelling at two speeds (300 and 760 mm/s) and by planting at three distances (260, 420 and 630 mm) with the working speed (300 mm/s), during travelling and transplanting. The results showed that the required power increased when the travelling speed was fast. One-way ANOVA for the planting distance and Duncan's multiple range test at a significance level of 0.05 were used to analyze the motor power using statistical analysis software. In addition, the required power increased when the planting distances were short at every working condition. The results of this study would provide useful information for the development an electric transplanter.

• Clean Technology
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• v.13 no.1 s.36
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• pp.16-21
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• 2007

This study estimated the effect of hydraulic residence time(HRT), influent total ammonia nitrogen(TAN) concentration, temperature and pH in the packed-bed bioreactor using immobilized nitrifiers. Removal rate of ammonia nitrogen was increased with decreasing HRT and the optimum HRT was 0.2 hour when influent TAN was $2g/m^3$. At this point, removal rate was $226.1\;g/m^3{\cdot}day$ and removal efficiency was 88.8%. Removal rate of ammonia nitrogen was Increased with increasing TAN concentration. Removal rate and efficiency of ammonia nitrogen were kept constant at $20{\sim}35^{\circ}C$ and pH $8{\sim}9$ value.

• Journal of Microbiology and Biotechnology
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• v.23 no.3
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• pp.430-435
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• 2013

Multidrug resistance, especially multidrug efflux mechanisms that extrude structurally unrelated cytotoxic compounds from the cell by multidrug transporters, is a serious problem and one of the main reasons for the failure of therapeutic treatment of infections by pathogenic microorganisms as well as of cancer cells. Streptococcus mutans is considered one of the primary causative agents of dental caries and periodontal disease, which comprise the most common oral diseases. A fragment of chromosomal DNA from S. mutans KCTC3065 was cloned using Escherichia coli KAM32 as host cells lacking major multidrug efflux pumps. Although E. coli KAM32 cells were very sensitive to many antimicrobial agents, the transformed cells harboring a recombinant plasmid became resistant to several structurally unrelated antimicrobial agents such as tetracycline, kanamycin, rhodamin 6G, ampicillin, acriflavine, ethidium bromide, and tetraphenylphosphonium chloride. This suggested that the cloned DNA fragment carries a gene encoding a multidrug efflux pump. Among 49 of the multidrug-resistant transformants, we report the functional gene cloning and characterization of the function of one multidrug efflux pump, namely MdeA from S. mutans, which was expressed in E. coli KAM32. Judging from the structural and biochemical properties, we concluded that MdeA is the first cloned and characterized multidrug efflux pump using the proton motive force as the energy for efflux drugs.

• Journal of Microbiology and Biotechnology
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• v.26 no.11
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• pp.1836-1844
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• 2016

Adipogenesis is one of the cellular processes and a highly controlled program. Nowadays, inhibition of adipogenesis has received attention as an effective way to regulate obesity. In the current study, we investigated the inhibition effect of a chloroform extract of Pleurotus eryngii var. ferulae 'Beesan No. 2' (CEBT) on adipogenesis in 3T3-L1 murine preadipocytes. Pleurotus eryngii var. ferulae is one of many varieties of King oyster mushroom and has been reported to have various biological activities, including antitumor and anti-inflammation effects. Biological activities of 'Beesan No. 2', a new cultivar of Pleurotus eryngii var. ferulae, have not yet been reported. In this study, we found that CEBT suppressed adipogenesis in 3T3-L1 cells through inhibition of key adipogenic transcription factors, such as peroxisome proliferatoractivated receptor ${\gamma}$ and CCAAT/enhancer binding protein ${\alpha}$. Additionally, CEBT reduced the expression of the IRS/PI3K/Akt signaling pathway and its downstream factors, including mammalian target of rapamycin and p70S6 kinase, which stimulate adipogenesis. Furthermore, ${\beta}-catenin$, a suppressor of adipogenesis, was increased in CEBT-treated cells. These results indicate that Pleurotus eryngii var. ferulae 'Beesan No. 2' effectively inhibited adipogenesis, so this mushroom has potential as an anti-obesity food and drug.

• Food Industry And Nutrition
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• v.2 no.1
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• pp.7-9
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• 1997

내열설 미생물, Thermus caldophilus CK24에 대한 탄수화물 생합성을 연구하는 과정에서 다양한 탄수화물 관련효소를 탐색하고 그레 대한 생화학적 및 분자생물학적 연구를 수행하고 있다. 일차로 내열성 미생물내 1) 당핵산염 합성효소와 당전이 효소, 2) 탄수화물 대사효소. 3)탄수화물 분해 및 전환효소의 존재를 HPLC/Bio-LC분석을 통하여 확인하고 이들에 대한 연구를 진행하고 있다. 본 연구발표에서는 포도당을 과당으로 전환하는 이성화효소(xylose isomerase), 그리고 맥아당을 트레할로스로 전환하는 트레할로스 합성효소(trehalose synthase)를 소개하고저 한다. 이성화효소는 이미 산업적 과당 생산에서 대규모적으로 사용되고 있는 식품산업효소이다. 본 연구에서는 Thermus caldophilus GK24, Thermus thermophilus HB8, Thermus flavus AT62 3종의 내열성 미생물에 대한 이성화효소 유전자를 클로닝 하고, 각 재조합하고 이성화효소를 대량생산하였다. 이 내열성 이성화효소는 최적 반응 온도가 8$0^{\circ}C$이고, 포도당을 과당으로 전환하는 수유른 55%이었다. 이러한 과당전환률은 이미 산업적으로 사용되고 있는 이성화효소의 과당전환률(43%)보다 훨씬 높은 것으로 과당 생산공정의 단순화의 생산성 향상에 결정적인 요인이라 할 수 있다. 한편 본 이성화효소의 산업적 특성을 증대하기 위하여 구조-기능관계 연구를 착수하였다. 우선 내열성 이산화 효소의 입체 구조를 결정하였고, 구조조정에 따른 기능적 특성을 조사하기 위하여 특정 위치의 선택적 변이 연구를 진행하고 있다. 끝으로 포도당 전이 효소를 추적하던 과정에서 맥아당을 트레할로스로 전환하는 새로운 효소를 Thermus caldo-philus GK24에서 발견하였다. 그 트레할로스 합성효소는 분자량이 약 110kDa이고 최적 반응온도가 75$^{\circ}C$이면, 조효소없이 맥아당을 트레할로스로 80%이상 전환해 주는 가역효소이었다. 본 연구에서는 효소반응의 조건과 특성을 조사하였고, 효소 아미노-밀단의 서열결정정보를 통하여 효소의 유전자를 클로닝 하고 그 유전자의 구조와 발현연구를 진행하고 있다.

• Journal of Ginseng Research
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• v.41 no.4
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• pp.602-607
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• 2017

Background: Panax ginseng is a traditional herb used for medicinal purposes in eastern Asia. P. ginseng contains various ginsenosides with pharmacological effects. In this study, floralginsenoside A (FGA), ginsenoside Rd (GRD), and ginsenoside Re (GRE) were purified from P. ginseng berry. Methods: Chemical structures of FGA, GRD, and GRE were determined based on spectroscopic methods, including fast atom bombardment mass spectroscopy, ID-nuclear magnetic resonance, and infrared spectroscopy. Inhibitory activities of these compounds on melanogenesis were studied by measuring the expression of protein and melanin content in the melan-a cell line. This inhibitory activity was confirmed by observing pigmentation and tyrosinase activities of zebrafish. Results: GRD, GRE, and FGA were not cytotoxic at concentrations less than $20{\mu}M$, $80{\mu}M$, and $160{\mu}M$ in melan-a cells, respectively. GRD, GRE, and FGA inhibited melanin biosynthesis in melan-a cells by 15.2%, 22.9%, and 23.9% at $20{\mu}M$, $80{\mu}M$, and $160{\mu}M$, respectively. FGA was observed to display the most potent inhibitory effect. In addition, FGA decreased microphthalmia-associated transcription factor protein expression in a dose-dependent manner. Moreover, FGA induced extracellular signal-regulated kinase phosphorylation level in melan-a cells. In addition, melanin pigment content and tyrosinase activity in zebrafish treated with FGA at $160{\mu}M$ were reduced. Conclusion: FGA showed the most potent inhibition of melanogenesis in both in vitro and in vivo studies. This study suggests that FGA purified from P. ginseng may be an effective melanogenesis inhibitor.

• Korean Journal of Agricultural Science
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• v.43 no.3
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• pp.496-505
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• 2016

The purpose of this study was to investigate the economic effects of a flame retardant aluminum screen developed by a company Economic effects were analyzed in terms of micro and macro-economic aspects. In the macro-economic aspect, economic effects were analyzed under the assumptions that the total import volume of flame retardant aluminum screen was approximately $50m^2$ in 2015 and that possible import substitution rates were 100%, 80%, and 60%. Results showed economic values of 2.25 billion won (100% import substitution rates), 1.8 billion won (80% import substitution rates), and 1.35 billion won (60% import substitution rates). If existing farms which had been using imported flame retardant aluminum screen replaced it newly developed with the flame-retardant aluminum screen developed in this study at rates of 100%, 80%, and 60%, the farms could save 750 million won, 60 million won, and 45 million won, respectively. Furthermore, the social cost savings from fire prevention could be 1.184 billion won. In the micro-economic aspect, if a farm with a typical-size ($1,000m^2$) greenhouse growing red pepper wanted to install flame retardant aluminum screen instead of generic aluminum screen, the farm may only pay an additional cost of 720,000 won. In comparison, if the farm chose fire insurance instead of flame-retardant aluminum screen, then the farm would pay 21,000,000 won for fire insurance. The above results show that the economic effect of flame retardant aluminum screen developed by the company would be be very efficient compared to the imported one.

• Korean Journal of Agricultural Science
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• v.44 no.3
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• pp.416-423
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• 2017

This study aimed to identify milling characteristics depending on the rotating speed of the main shaft of the cutting-type rice milling machine which can minimize the conventional milling process. Brown rice, which was produced in Gunsan-si, Jeollabuk-do, Republic of Korea, in 2016, was used as the experimental material. The milling characteristics of white rice were measured under four different rotating speeds of main shaft: 950 - 1,050 rpm, 1,000 - 1,100 rpm, 1,050 - 1,150 rpm, and 1,100 - 1,160 rpm. For each shaft speed, 300 kg of brown rice was processed, and the milling characteristics were measured according to the whiteness, grain temperature, cracked rice ratio, broken rice ratio, turbidity, and energy consumption. The whiteness of rice grain was found to be consistent at around $40{\pm}0.5$ only when milled at the shaft speed of 950 - 1,050 or 1,000 - 1,100 rpm. The grain temperature during the milling process increased by 11.35 to $11.85^{\circ}C$, showing little differences amongst shaft speeds. The cracked rice ratio increased by 8.2 to 10.4% at all conditions. The broken rice ratio ranged from 0.58 to 0.76%, reflecting a low level. The turbidity after milling was 54.8 ppm when milled at 1,000 - 1,100 rpm. Energy consumption of 12.98 and 12.18 kWh/ton were recorded at the shaft speed of 1,000 - 1,100 and 1,050 - 1,150 rpm, respectively. The result of this study indicates that the optimal rotating speed of main shaft would be 1,000 - 1,100 rpm for a cutting-type rice milling machine.

• The Journal of Fisheries Business Administration
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• v.34 no.1
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• pp.137-156
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• 2003

Increasingly, leisure time is being used for outdoor recreational activities, and fishing is one of the principal forms of marine recreation. Marine recreational fishing is a popular activity in Korea and this activity has led to the development of a sector of substantial social and economic value. Also it is considered as one of the important outdoor leisure industries in Korea. With rising of income level and development of marine outdoor leisure industries, social, economic demand increase of marine recreational fishing are showing us new advance ability of marine aquatic bio-industry. However the recreational use of fish stocks has become an important consideration in the public and environmental economic analysis of management aspect of fishing, having grown considerably over recent years to reach a level in Korea where the fish stocks and coastal ecosystem has become a significant management problem. we are inevitably facing marine environmental deterioration and overfishing in marine recreational fishing. In this study, not only resources and environmental problems which are occurred by recreational fishers, but also illegal fishing behaviors and other problems such as market's failure are going to analyze basic management theories and methods of recreational fishing through mathematical principals and economic rents which maximize net social benefits. In view of the likelihood of marine recreational fishers adopting high rates of discount, the conservation of fish resources would appear to require continual public surveillance and control of the physical yield and condition of the fish stocks and the optimal use level. The institutional management of recreational fisheries is the way of escaping the collapse of recreational fisheries just like as the situation of management's failure of commercial fisheries worldwide. One of the effective management measure is a license system. In this system, optimal fee is paid by recreational fishers, which prevent them from overfishing, environmental problems to some extents and carry out the optimal number of outings. And money obtained by license fee should be spent for more improvement fishing culture and welfare for marine recreational fishing. Marine recreational fishing is to be promoted under sound conservation and management principles.

• Journal of the Semiconductor & Display Technology
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• v.10 no.1
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• pp.33-41
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• 2011

Due to the recent quantum leaps forward in bio-, nano-, and information-technologies (BT, NT and IT), the precisionization and miniaturization of mechanical and electrical components are in high demand. In particular, the ITrelated equipments that take a great part in our domestic industry are in the area requiring high precision technologies. As a consequence, the researches on the development vibration isolation systems that diminish external disturbance or internal vibration are highly required. Among the components comprising the vibration isolation system, air spring has become on a focal point for the researchers due to its merits. This air spring is able to support heavy loads, keep a low natural frequency despite of having a lower value of stiffness, and control the performance of vibration isolation. However, sometimes the sole use of air spring is in demand due to some economic reasons. Under this circumstance, the damping effect of sole air spring may not enough to reduce sufficient amount of vibration. In this study, the air spring mount system connecting with an external chamber is proposed to increase or control the damping effect. To investigate its damping mechanism, the thermal and dynamic behaviors of the system is examined through a theoretical modeling approach in this part of research. In this approach, thermomechanical and Helmholtz resonator type models are to be employed for the air spring/external chambers and connecting tube system, respectively. The frequency response functions (FRFs) derived from the modeling effort are evaluated with physical parametric values and the effects of connecting tube length on these FRFs are identified through computer simulations.