• 환경위생공학
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• 제5권2호
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• pp.45-52
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• 1990

This study is to discuss limiting factors influenced on the removal efficiency of organic materials investigated using the polypropyrene biofilter which appropriate to attach micro-organism in order to apply the contact oxidation proce,:5. The results obtained in the experiment were as follows : 1. In the range o: pH 4.0~ 12.0 was obtained the removal efficiency of COD higher than 85% It was proved that variation of pH(4.0 ~ 12.0) was nothing to do with the removal efficiency of substrate in continuous reactor. 2. Temperature to obtain removal efficiency of COD higher than 85% was $10^{\circ}$ ~$40^{\circ}$. Removal efficiency of COD was no less than those at high temperature if MLVSS concentration was maintained 8,000~ 15,000 m/1. 3. In the continuous reactor, the volumetric loading of COD for removal efficiency higher than 95% had to be 0.5~1.5 kg COD/.d below. And then the HRT was Bhrs. 4. In comparison with the conventional activate sludge process, the contact oxidation process was excellent in removal efficiency, sludge production rate and maintenance.

• 한국자동차공학회논문집
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• 제2권1호
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• pp.84-95
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• 1994

The effects of punch and blank shapes in the rectangular cup drawing process are examined experimentally to improve the formabilities. For this purpose, three blank shapes which are h-bl., G-bl., and T-bl., and five punch shape factors which are the ratios of two adjacent side lengths in rectangular cross section are adopted. The constructing methods of the three blank shapes are as follows. The h-bl. is designed by slip-line theory, and the G-bl. is selected for the similar shape to the punch. The T-bl. is obtained by the drawing method which is introduced in the technical references. The five punch shape factors are selected for length/width=1, 1.25, 1.5, 1.75 and 2. The experimental procedures are performed for all the above forming conditions to investigate and compare the formabilities. As a result, it is verified experimentally that the rectangular cups drawn by the h-bl. are more ideal than those drawn by G-bl. and T-bl.. They have not only higher limiting drawing ratio, more uniformity in drawn cup heights and more ideal thickness distributions, but also need relatively less maximum drawing forces.

• 한국표면공학회지
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• 제32권6호
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• pp.695-702
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• 1999

We have explored the factors affecting the resistivity of Cu (Mg) alloy, which was prepared by sputtering. The results show that the resistivity is a function of Mg content, annealing temperature, annealing time, and Cu-alloy thickness. Addition of Mg to copper increases the resistivity through solute scattering. In addition, increasing Mg content promotes the interfacial reaction between Mg and SiO$_2$ to produce the free silicon and the generated free silicon dissolves into copper, resulting in a significant increase of resistivity. Furthermore, increasing oxidation temperature rapidly decreases the resistivity at the initial stage of oxidation and then continues to increase the resistivity to the saturation value with increasing oxidation time. The saturation value depends on the residual Mg content and the thickness of the alloy. TEM and AES analyses reveal that dense, uniform MgO grows to the limiting thickness of about $150\AA$. However, interfacial MgO does not show the limiting thickness, instead continues to grow until Mg is completely exhausted. From these facts, we proposed the maximum available Mg content needed to from the dense MgO on the surface and suppress the excessive interfacial reaction.

• Journal of Plant Biology
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• 제14권3호
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• pp.1-20
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• 1971

Ecological factors limiting Stipa pulchra have been determined in experimental gardens and at several sites in the hills south and east of Monterey, California. The Stipa pulchrafacies of Valley Grassland communities were found to be dominated by that species, though a total of 36 grasses and forbs were collected and identified. Basal area was not large, but aerial cover by Stipa alone averaged over 50 per cent. Across an ecotone between a Stipa association and the California Annual Type a sudden and dramatic change was recorded. Soil measurements there, and in other nearby areas, showed a much higher clay content with more available water and elemental phosphorus at the Stipa sites. Germination of Stipa seeds was high under all laboratory and field conditions, though growth of seeldings was highly variable. Seedlings grown in Stipa woil with an abundance of water were vigorous and reached anthesis the first year. In other soils they grew less, and when grown in competition with Avena fatua they scarcely grew at all. These findings indicate that when established on desirable soils, Stipa competes well and apparently precludes the dominance of Avena fatua and other large annual grasses. On the other hand, because of a lack of vigor in its seedlings, Stipa cannot reinvade the rich more friable soils on which it was once found, and on which it was shown to grow satisfactorily. This supports the contention that Sipa pulchra was the dominant grass through much of the Valley Grassland and Foothill Woodland, but also indicates that well-drained soils and those poor in mineral nutrients probalby never supported such associations.

• Applied Biological Chemistry
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• 제19권3호
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• pp.162-171
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• 1976

대사과정(代謝過程)에 있어서 율속단계(律速段階)의 결정은 그 대사(代謝)의 성질을 이해하는 데 대단히 중요한 것이다 저자들은 이것의 결정을 위해서 열역학적(熱力學的) 방법(方法) 대신에 수정된 효소적(酵素的) 방법(方法)을 제시 하였다 이 방법은 단계로 된 대사과정(代謝過程)에서 율속단계(律速段階)에 고유한 효소(酵素)를 가(加)했을 때는 다른 어떤 단계(段階)에 고유한 효소(酵素)를 가(加)했을 때보다도 전체적인 대사(代謝) 반응속도(反應速度)가 가잠 증가한다는 가정(假定)에 기초를 둔 것이다. 본 연구에서는 수정된 효소적(酵素的) 방법(方法)에 의한 반응속도(反應速度) 측정(測定)에 있어서, 이에 영향을 미치는 수종(數種)의 인자(因子)에 대하여 해석(解析)하였으며 주로 동일한 반응속도(反應速度) 형태로 구성된 대사과정(代謝過程)에 대하여 해석(解析)하였다. 이 결과(結果), 본 방법에 의한 율속단계(律速段階)의 결정(決定)은 약간의 제한(制限)이 가(加)해질 경우 임의 형태의 기작(機作)으로 子성된 대사과정(代謝過程)에서도 측정(測定)이 가능하다는 것을 보여 주고 있다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2001년도 학술발표회 발표논문집
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• pp.479-483
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• 2001

This Study was carried out to know the soil properties and the quality of shallow groundwater in the plastic film house fields around mid-Korea. This study was conducted at 11 sites in Suweon, Pyungtaek, Yongin, and Chunchen on May, June, July and August in 1999. The the average concentration of nitrate-nitrogen was 19.1 mg/L, it reached almost to the limiting level, 20 mg/L. Moreover about 36.4% of survey sites exceeded limiting level to agricultural groundwater quality. And Sulfur concentrations also at some sites exceeded to agricultural groundwater quality limit level (50 mg/L), which could make damage to the crop. Nitrate-nitrogen, which is one of the most important factors in the groundwater quality, It has highly positive correlation with any other ion in groundwater. This result showed that groundwater quality management practices should be taken for the agricultural production as well as for environment at the plastic film house areas.

• 소성∙가공
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• 제9권4호
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• pp.379-388
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• 2000

This study aims to examine the influence of experimental and numerical factors on the results of the test and finite element simulation to evaluate the formability of sheet metals. The stretch-forming test with a hemispherical punch is carried out to obtain the limiting dome height (LDH) and forming limit diagram (FLD) for several kinds of aluminium and steel sheet. The results of the LDH and FLD tests are analysed to find any correlation with the uniaxial tensile properties. It proves that the size of the prescribed grid has great influence on the measured value of strain. The finite element analysis of the punch stretching process is also carried out and the result is compared with the experimental data. The influence of the numerical parameters such as friction coefficient, element size and anisotropy model on the simulation results tms out to be very considerable.

• KSBB Journal
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• 제7권2호
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• pp.92-95
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• 1992

동물세포 대량 배양의 저혈청 배지를 개발하기 위하여 융합제작한 하이브리도마 KA112를 대상으로 혈청의 역할을 살펴본 다음, 혈청의 구성인자를 최고세포 농도를 결정하는 소모성 영양인자와 세포성장속도를 결정하는 성장 제어인자로 나눈 혈청 역할모델을 개발하여 실험 결과와 비교 검토하였다. 이 모델이 의하면 7%이상의 혈청 첨가시에는 혈청내의 소모성 인자가 그와 같은 역할을 맡게 되며, 3% 첨가시에는 성장 제어 인자의 고갈로 인해 세포성장속도가 제한을 받는다. 동시에 소모성 단일 인자가 혈청농도에 의하여 limiting하게 됨에 따라 최고 도달 세포 농도와 세포 성장 속도를 제어함을 설명할 수도 있다. 이러한 실험결과들은 혈청농도와 기저배지 성분들의 농도를 항상 균형있게 고려해 주어야 함을 보여주고 있다.

• Asian-Australasian Journal of Animal Sciences
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• 제12권8호
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• pp.1298-1309
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• 1999

The nutritional value of protein varies between feedstuffs. It is possible to feed animals using crystalline amino acids as a sole nitrogen source, but in practice only some limiting amino acids are added to the diet. In order to use feedstuffs efficiently, it is important to determine exact amino acid requirements. Reported values differ widely because the requirements are affected by various factors. In this report, therefore, the factors affecting amino acid requirements are reviewed as follows: 1) availability of dietary amino acids, conversion factors of nitrogen to protein, interaction of amino acids, and strain, sex and age of animals; 2) amino acid requirements for maximum performance and maintenance, usefulness of non-essential amino acids; 3) plasma amino acid concentration as a parameter to determine amino acid requirements; and 4) nitrogen excretion to reduce environmental pollution. These factors should be considered, it is to improve the dietary efficiency, which is to reduce excess nitrogen excretion for environmental pollution.

• 한국비블리아학회지
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• 제31권3호
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• pp.191-211
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• 2020

본 연구는 시각장애인들의 독서보조기기를 이용한 정보접근에서 발생하는 한계와 문제점 등을 확인하고, 이를 기반으로 독서보조기기를 이용한 대체자료 이용 활성화 방안을 제안하는데 주된 목적을 두고 있다. 이를 위해 시각장애인 성인을 대상으로 설문조사를 수행하였으며, 설문 분석 결과를 통해 독서보조기기의 이용을 활성화하는데 있어서의 제한요인을 여섯 가지 측면으로 도출하였다. 도출한 제한요인을 중심으로 독서보조기기 이용 활성화를 위한 방안을 정책적, 운영적 측면으로 구분하여 제안하였다. 정책적 측면에서는 저가의 독서보조기기 개발, 독서보조기기 지원 정책에 대한 인지도 제고, 독서보조기기 적용성 향상을 위한 웹 표준 지침 준수 방안을 제안하였으며, 운영적 측면에서는 시각 이외에 청각 활용 기능의 보강, 독서보조기기 활용 관련 정보서비스 확충, 독서보조기기의 휴대성 강화 등을 제안하였다.