• 농업과학연구
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• 제44권1호
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• pp.86-94
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• 2017

In Korea, chemical analysis of animal feed is done through authorized feed analysis laboratories (AFALs). Analysis results among the AFALs need to be similar or within acceptable variations; however, there is no experimental evidence of their comparability. We aimed to determine the level of variation of feed chemical analysis results from different AFALs. For this, we requested analysis of four kinds of feed (corn, soybean meal, corn gluten feed, and ryegrass) to eight AFALs and the Cumberland Valley Analytical Services (CVAS) which is an internationally well-recognized feed analysis laboratory. The AFALs spent more time on analysis than did CVAS. Fiber analysis results varied significantly among laboratories. However, moisture, CP, and ash content values showed almost no variation. At least one AFAL obtained results with significant differences from CVAS for all tested values. These differences can be explained by the followings: 1) the standard methods for feed analysis (SMFA) established for AFALs are not detailed enough to control the analytical variations among different laboratories and 2) guidelines are insufficient for the quality control of analysis results in Korea. Failure to accurately identify the nutritional components of the feed could mean failure to provide adequate nutrients to the animals. Therefore, efforts to reduce the differences among AFALs, such as revising SMFA and publishing guidelines on quality control of feed analysis results, are important.

• Applied Biological Chemistry
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• 제27권
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• pp.18-28
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• 1984

In order to improve feed values of Korean agricultural by-products, various treatments including physical, chemical, physicochemical and fermentation were suggested in th is review article. Physical treatments such as chopping, grinding and pelleting reduce partiole size of agricultural by-products, and increase passage rate from the rumen, thus may increase voluntary feed intake and weight gain. Digestibility and voluntary feed intake of straw, rice hull and sawdust, also, may be increased by chemical treatment using sodium hydroxide or ammonia. Especially, because nitrogen content of by-products increase and toxic problem is not posed by ammonia treatment, it's practical usage is recommended in Korea. Silage or fermentation treatment using principles of microbial fermentation may improve palatability of low quality by-products. As mentioned above, it is concluded that various treatments suggested are desirable and improve feed value but may raise several problems. Unfortunately, because cost for installation and products is great and processing work is complicate, farmers are not using well these processing methods until now. Therefore, in order to increase the practical usage at farm level, it is thought that many research works be achieved for efficient process which have simple operation and low installation cost.

• Journal of Advanced Marine Engineering and Technology
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• 제33권5호
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• pp.729-737
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• 2009

This paper introduces the machine tools feed system, which can be optimized the control's performance through simulation and the adjustment of the mechanical components. One method simulates the frequency response of the speed-loop with the design value using the MATLAB application, so that all of the interpolation axis can be equal to the response bandwidth, resulting in a high accuracy rate. The other method sees the mechanical component being adjusted by analyzing the results of various experiments. Lastly, this client's program is able to change the parameters that are related to the FFD, as well as the parameters in the friction compensation of the OPEN-CNC.

• 한국전자파학회논문지
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• 제11권6호
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• pp.859-867
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• 2000

본 논문에서는 프로브로 급전되는 단일 원형 마이크로스트립 안테나 위에 게이돔과 같은 또 다른 유전체가 씌어져 있는 구조에 대해서 모멘트 법을 이용하여 해석을 하였다. 급전 구조의 정확한 해석을 위하여 어태치먼트 모드를 이용하여 패치와 급전겅에서의 전류의 연속성을 보장해 줌으로써, 급전점에서 급격히 변하는 전류성분들을 표현할 수 있었다. 해석된 결과는 실험을 통하여 검증되었고, 서로 잘 일치하고 있음을 확인할수 있었다.

• Journal of Microbiology and Biotechnology
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• 제19권9호
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• pp.888-897
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• 2009

Lipase diversity in glacier soil was assessed by culture-independent metagenomic DNA fragment screening and confirmed by cell culture experiments. A set of degenerate PCR primers specific for lipases of the hormone-sensitive lipase family was designed based on conserved motifs and used to directly PCR amplify metagenomic DNA from glacier soil. These products were used to construct a lipase fragment clone library. Among the 300 clones sequenced for the analysis, 201 clones encoding partiallipases shared 51-82% identity to known lipases in GenBank. Based on a phylogenetic analysis, five divergent clusters were established, one of which may represent a previously unidentified lipase subfamily. In the culture study, 11 lipase-producing bacteria were selectively isolated and characterized by 16S rDNA sequences. Using the above-mentioned degenerate primers, seven lipase gene fragments were cloned, but not all of them could be accounted for by the clones in the library. Two full-length lipase genes obtained by TAIL-PCR were expressed in Pichia pastoris and characterized. Both were authentic lipases with optimum temperatures of ${\le}40^{\circ}C$. Our study indicates the abundant lipase diversity in glacier soil as well as the feasibility of sequence-based screening in discovering new lipase genes from complex environmental samples.

• 한국가금학회지
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• 제39권1호
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• pp.33-37
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• 2012

One of the biggest challenges for the animal feed industry in the coming years will be to meet the growing demand in animal protein in light of increased cost of feed ingredient as well as tougher restrictions on the use of antimicrobial growth promoters imposed by consumers and governments. A key focus area will be to maximise feed efficiency and minimise nutrient waste. It has been widely acknowledged that the composition of the intestinal microflora is closely related to intestinal health and performance of animals. Advanced microbial techniques have shown a close relationship between bacterial communities and their ability to modulate nutrient absorption and processing. In addition it has been recognised that modulating the immune response has significant impact on overall health as well as overall nutrient demand. Molecular techniques are a useful tool to gain an understanding of the impact of dietary interventions including the use of functional feed additives on specific changes in microbial communities or the immune system. Most these techniques however focus on the evaluation of large changes in bacterial compositions and often underestimate or neglect to recognise small changes in microbial diversity or behaviour changes without any measurable immune response. The key to understanding the relationship between specific nutritional intervention and the impact on health and performance lies in a deeper understanding of the impact of these nutrients on the expression of specific genes or specific metabolic pathways. The development of molecular tools as a result of developments in the field of Nutrigenomics has enabled researchers to study the effects of specific nutrients on the whole genome or in other words, the effect of thousands of genes simultaneously, and has opened a completely different avenue for nutritional research.

• 한국건설관리학회논문집
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• 제16권5호
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• pp.65-76
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• 2015

해외 플랜트 사업에서의 고부가가치를 창출하기 위해서는 기획 타당성조사, 프로젝트종합관리, FEED 및 기본설계 등 분야의 기술경쟁력 강화가 시급하다. 특히, FEED 업무는 프로젝트 전체에 대한 영향력이 절대적이고, 또한 기자재 및 패키지 산업의 경쟁력 강화에도 결정적 역할을 한다. 그럼에도 불구하고, FEED 관련 선행연구들은 설계업무 중심의 프로세스 및 성과물을 위한 연구가 대부분이며, 프로젝트 전체에 영향을 미치는 관리적 관점의 FEED 업무에 대한 연구는 미흡한 실정이다. 따라서 본 연구에서는 발전플랜트 중 화력발전소를 대상으로 사업관리 관점의 FEED 업무 프로세스 구조 및 항목을 제안하였다. 도출된 FEED 관리 업무는 3개의 레벨로 나누어진 계층적 구조를 가지고 있으며, 업무 항목에 대한 전문가 검증을 실시하였다. 또한 FEED 관리 업무에 대한 평가지표별 평가를 통해 결과를 분석한 결과 설계 중심의 업무들은 역량이 높지만 중요도가 높은 관리적 관점의 FEED 업무들의 역량은 부족한 것으로 나타났다. 그러므로 본 연구에서 제안한 FEED 관리업무 프로세스 구조는 FEED 역량 강화를 위한 가이드라인이 될 것이라 기대한다.

• 한국음향학회지
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• 제23권4호
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• pp.303-308
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• 2004

본 논문에서는 전력 증폭기의 선형화를 위해 제안된 feed-forward 선형화 방식을 IMT-2000용 송신 시스템에 적용한 새로운 송신 시스템 구조를 제안한다. 이 시스템에서 feed-forward 구조는 왜곡 성분을 비교하고 제거하기 위해 보조신호(reference signal)을 필요로 하는데, 이 보조신호는 무시할 정도로 낮은 왜곡을 갖도록 낮은 입력 동작 범위에서 동작하는 두 번째 변조기에서 만들어 진다. 이런 구조로 한 결과송신 시스템에서 증폭기뿐만 아니라 변조기의 왜곡을 줄일 수 있다는 큰 장점이 있다. 본 논문의 시스템은 Agilent 社의 EEsoft ADS ver.2002를 사용하여 설계하였으며, 입력은 1.98GHz 주파수 대역에서 2MHz의 주파수 간격을 갖는 2-tone으로 하였고, 약 49.95dB의 IMD 개선 특성을 얻어, 본 논문에서 제안하는 시스템은 간단함과 선형성을 동시에 제공할 수 있다는 것을 입증하였다.

• Membrane and Water Treatment
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• 제2권3호
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• pp.159-173
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• 2011

The air gap membrane distillation (AGMD) process was applied for water desalination. The main objective of the present work was to study the heat and mass transfer mechanism of the process. The experiments were performed on a flat sheet module using aqueous NaCl solutions as a feed. The membrane employed was hydrophobic PTFE of pore size 0.22 ${\mu}m$. A mathematical model is proposed to evaluate the membrane mass transfer coefficient, thermal boundary layers' heat transfer coefficients, membrane / liquid interface temperatures and the temperature polarization coefficients. The mass transfer model was validated by the experimentally and fitted well with the combined Knudsen and molecular diffusion mechanism. The mass transfer coefficient increased with an increase in feed bulk temperature. The experimental parameters such as, feed temperature, 313 to 333 K, feed velocity, 0.8 to 1.8 m/s (turbulent flow region) were analyzed. The permeation fluxes increased with feed temperature and velocity. The effect of feed bulk temperature on the boundary layers' heat transfer coefficients was shown and fairly discussed. The temperature polarization coefficient increased with feed velocity and decreased with temperature. The values obtained were 0.56 to 0.82, indicating the effective heat transfer of the system. The fouling was observed during the 90 h experimental run in the application of natural ground water and seawater. The time dependent fouling resistance can be added in the total transport resistance.

• 대한기계학회논문집A
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• 제27권12호
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• pp.2028-2038
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• 2003

High-speed feed drive systems have been widely used in the manufacturing and semiconductor industries. Specifications for high-speed systems require more advanced capabilities than conventional feed drive systems. It is necessary to devise special design concepts to achieve the level of performance for high-speed feed drive systems. In this paper, an integrated design method is proposed for high-speed feed drive systems in which the interactions between mechanical and electrical subsystems ought to be considered simultaneously during the design process. Based on the integrated design method, a nonlinear optimal design procedure of mechanical subsystems considering the Abbe and radius errors is accomplished through the design process of electrical subsystems satisfying the control stability and the saturation condition of actuators as well as the relative stability. Both mechanical and electrical parameters are considered as design variables. Simulations and numerical case studies show that the integrated design method of high-speed feed drive systems creates results satisfying the desired performances of mechatronic systems.