• 한국해양공학회지
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• 제4권2호
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• pp.244-244
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• 1990

This paper deals with investigating experimentally the effects of PWHT on the weld quality such as strength, toughness, hardness and micro-structure of the welded joints in friction welding of torsion bar material SUP9A bar to bar. The results obtained are summarized as follows; 1) It was certified that the condition of the post-weld heat treatment(PWHT) for the friction welded joints was very satisfactory because both strength and toughness of the joints were improved as almost same as those of the base metal or better by the PWHT. 2) The peak of hardness distribution of the friction welded joints can be eliminated by PWHT, resulting in being almost equalized at the weld interface, the HAZ(heat affected zone) and the base metal. 3) The micro-structure of the base meta., HAZ and weld interface(WI) of friction welded joints welded at the optimum welding condition consists of the same sorbite structure obtained by PWHT and fined sorbite at WI, resulting in increasing toughness as well as strength, and no micro structural defect has been found at the friction welded zone.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 춘계학술대회 논문집
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• pp.49-51
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• 1988

The heat treatment condition and aging behavior of melt spun amorphous $Fe_{78}B_{13}Si_9$(Metglas 26058-2) were studied with investigating its magnetic properties, i.e., Br, $B_l$, Hc. The optimum heat treatment condition was $400^{\circ}C$, 1 hour under the external field of 200e, and aging was due to the surface oxidation and the appearance of local CSRO (chemical short lange order) with time and temperature. In addition. we investigated the effects of the thickness of the amorphous ribbons on the magnetic properties and aging effect of them.

• 한국약용작물학회지
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• 제9권2호
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• pp.166-172
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• 2001

본 연구는 헛개나무 종자의 휴면 타파 방법과 발아 조건을 구명 하고자 실시하였다. 종피를 제거하지 않은 종자는 온도와 상관없이 발아하지 않았으나 종피를 제거하였을 경우에는 $15^{\circ}C$에서 94%가 발아되었다. 종피를 파상하기 위한 휴면타파 방법은 농황산을 40분간 처리하는 것이 효과적이었다. 종자를 건조 저장하였을 경우 채종 후 5년까지도 발아능력은 유지하고 있으나 발아율이 다소 낮아졌고 평균발아일수가 길었다. 장기(5년) 저장한 종자는 30일 이상의 저온처리에 의하여 발아율이 높아져 저온처리효과가 인정되었다.

• 청정기술
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• 제8권2호
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• pp.67-76
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• 2002

Dewatered sludge of 400,000t/y from water treatment plants in Korea is being disposed through landfill and ocean dumping. However, the disposal is posing more and more serious environmental problems at the same time not only because of landfill site shortage in municipal suburbs, but because of the concern it will contaminate the oceans. In this study, the research on utilizing the sludge dried by flash dryer as covering soil in the landfill sites was carried out to solve these problems on environmental affinity. Both dewatered and dried sludge were exposed to the natural condition and observed according to the atmospheric changes. An experiment of soil engineering characteristics of the dried sludge and tests on mixed sludge(silty sandy soil : dried sludge = 10:90 ~ 30:70) such as particle size distribution, liquid and plastic limit, moisture content, specific gravity and compaction test were carried out. According to the compaction test, the compaction was confirmed as the optimum water content ratio was observed in the condition of SM-silty sand of particle size distribution, NP of liquid and plastic limit, 101.4% of moisture content, 2.04~2.12 of specific gravity. The results showed that dried sludges mixed with at least 30% of natural soil could be used as daily covering soil in the landfill sites.

• 한국작물학회지
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• 제38권3호
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• pp.240-244
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• 1993

야콘의 재배기술의 확립을 위하여 멀칭효과 및 재식밀도 실험을 한 결과는 다음과 같다. 1. 지상부 생육은 7월 중순부터 직선적으로 증가하였으며, 밀칭구나 비멀칭구에서 재식밀도가 높을수록 초장의 생육이 양호하였고, 특히 70 ${\times}$ 55cm에서 가장 좋았다. 2. 측지수는 정식 후 3개월부터 발생하였으며, 멀칭 및 재식밀도에 따라 유의한 차이를 나타내지 않았다. 3. 야콘괴경의 생체수량은 멀칭구가 비멀칭구 보다 높았으며, 멀칭구에서는 70${\times}$40cm구가 3561.7kg으로 가장 높았다. 4. 괴근수는 멀칭구에서 밀식할수록 많았으며, 근경과 근장에서는 유의적인 차이가 없었다.

• 상하수도학회지
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• 제20권1호
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• pp.138-146
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• 2006

The characteristics of backwash and concentrate discharges depend upon the quality of the water being treated and the net recovery of the membrane system. This paper is to indicate a design methods on the capacities of residuals treatment facilities in membrane processes for drinking water. We operated a demonstration membrane plant with a recovery rate of 90% for designing G-water treatment plant. We investigated on design parameter (optimum coagulant dosage and surface loading rate etc.) to design efficiently the residuals treatment facilities. The settling test was conducted with 1m columns dosing PACl to kaolin and membrane residuals under the experimental condition that discharge permit was under a 60mg/L. When the quantity of membrane residuals was $1,575m^3/day$, the estimated results for 1st thickener demonstrated the surface loading rate of 14.4m/day, detention time of 5.83hr, available depth of 3.5m.

• 복식
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• 제36권
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• pp.109-119
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• 1998

For the purpose of standardization and practicability of natural dyeing, the mordanting and dyeing properties of Caseaslpinia Sappan, L. and Brazilin were studied. Appropriate extraction, dyeing and mordanting condition of Caeaslpinia Sappan, L. were determined, and the effect of mordanting method on dye up-take adn color fastness of dyed fabric was investigated. The most absorbance of Caeaslpinia Sappan, L. solution was 445nm, Brazilin was 448nm. The color of bazilin solution was affected by pH 7~9. The optimum temperature to extract Caesalpinia Sappan, L. was 10$0^{\circ}C$ adn dyeing solution for 1 hour. In case mordants concentration, the most absorbance was 0.3%. In case mordanting test, the best and proper temperature to quantities of absorbed mordants in silk was 8$0^{\circ}C$ and the most quantities of absorbed mordants in silk was mordant treatment by Cu. Effective dyeing time to silk was 60min. Effective mordanting temperature was 8$0^{\circ}C$, and its time was 30min. K/S value of dyeing fabrics was recoginazed by mordanting treat-ment, specially Fe, Sn, Al, Cu. K/S value of pre-mordanting was higher than post-mordanting. After soaping treatment K/S value of pre- and post-mordanting silk was decreased and 0.1%(W/V) quantity of mordant was sufficient for treatment. In the case of Caeaslpinia Sappan, L. fastness was increased by mordanting treatment. Mordants and mordanting treatment method affected the amount of absorption and color change of dyed silk.

• 한국주조공학회지
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• 제32권5호
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• pp.231-240
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• 2012

In present study, the effect of heat treatment on the microstructure and mechanical properties of the gravity cast superchargers housing using A356 alloy were investigated. In order to identify the characteristics of superchagers housing casting with heat treatment, Vickers hardness test, electrical conductivity test, opical and scanning electron microscopy were performed. And also, to investigate their mechanical properties, the T6 treated superchagers housing casting in optimum heat treatment condition were carried out tensile test using UTM (Universal Testing Machine).

• 한국물환경학회지
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• 제21권1호
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• pp.34-39
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• 2005

The performance of elutriated acid fermentation with slurry-type piggery waste was investigated, especially to evaluate the effects of temperature and pre-treatment. In the first phase, the acid elutriation reactor with piggery waste after centrifugation operated at both mesophilic and thermophilic conditions to evaluate the effect of temperature. Solubilization yield($gVFAs/gSCOD_{prod.}$) and acidification rate($gVFAs/gSCOD_{prod.}$) in the thermophilic digestion were 0.45 and 0.55, which were higher than those of the mesophilic digestion, 0.25 and 0.45. In addition, the acid elutriation reactor at thermophilic temperature is more effective in removing e-coli. In the second phase, the acid elutriation reactor was fed with piggery waste before centrifugation. With piggery wastes before centrifugation, the solubilization yield and the acidificaton rate were 0.40 and 0.80, respectively, which were higher than the rates using piggery waste after centrifugation at both mesophilic and thermophilic conditions. The higher sludge volume reduction of 80% benefits sludge management. Furthermore, economical advantages can be achieved by removing the pre-treatment process, such as centrifugation. Consequently, the treatment with piggery waste before centrifugation proved to be effective. Also, the optimum temperature condition was estimated at mesophilic or thermophilic conditions, considering solubilization yields and acidification rates, though the system should be heated.

• 한국환경과학회지
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• 제12권3호
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• pp.281-286
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• 2003

This study was conducted to evaluate the feasibility of ammonia removal by zeolite adsorption in drinking water treatment. In generally, drinking water treatment process is conducted coagulation/flocculation, sedimentation, sand filtration and disinfection. We tested feasibility with two method, one is powdered zeolite dosing to coagulation tank and the other is to substitute granular zeolite for sand of sand filter. In powdered zeolite test, raw water is used tap water with putting of 2 mg/l of NH$_4$$\^$+/-N. Filtration of granular zeolite was conducted with 80 cm of effective column high and 120 m/d of flow rate. At above 100 mg/1 of zeolite dosage, ammonia concentration was decreased below 0.5 mg/l of NH$_4$$\^$+/-N in powdered zeolite test. But, turbidity was increased to 30 NTU by powdered zeolite dosage. That turbidity was scarcely decreased in generally coagulant using condition in drinking water treatment. In granular zeolite test, ammonia was not detected in treated water until 8 days. This result suggest that using of granular zeolite in sand filter could be removal ammonia in winter. But we need regeneration at zeolite filtration for ammonia removal. So, it is to make clear that zeolite regeneration ability was compared KCl with NaCl. The result reveal that KCl was more excellent than NaCl. Optimum regeneration concentration of KCl was revealed 100 mM. Regeneration efficient was not increased at pH range 10∼12.5.