• 에너지공학
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• 제26권3호
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• pp.105-112
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• 2017

우리는 원자력발전시스템에서부터 상수도까지 많은 배관시스템을 사용하고 있다. 그리고 이들 배관시스템의 적절한 운용을 위하여 배관시스템의 유지 및 보수 등을 수행하고 있다. 특히 한국지역난방공사와 같은 대형플랜트 배관시스템의 고장은 기업의 생산성과 이익에 직결된 문제일 뿐만 아니라 국민의 안전과 편익과 같은 매우 중요한 문제를 유발할 수 있기 때문에 빠른 대응과 안전한 수리가 가장 중요한 문제로 대두되고 있다. 본 연구에서는 한국지역난방공사 사용 중인 이중보온 열수송관(300A)의 유지보수를 위하여 액화질소를 이용한 배관 동결차수공법을 개발하였다. 본 연구에서는 전산해석기법을 채용하여 대상 열수송관과 전용 재킷에 대한 내부 유동 및 열전달 해석을 수행하여 최적의 시스템을 선정하고, 상세 모델을 설계, 제작하였다. 실험실 규모 시험장치를 개발하여 차수공법에 대한 자체시험을 수행하고, 한국지역난방공사 세종지사 Test bed에서 현장적용 성능평가 시험을 수행하였다.

• 한국전기전자재료학회논문지
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• 제22권8호
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• pp.645-649
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• 2009

We investigated the effects of a high density $O_2$ plasma treatment on the structural and electrical properties of Ga-, B- codoped ZnO (GZOB) films. The GZOB films were deposited on polymer substrate without substrate heating by DC magnetron sputtering. Prior to the GZOB film growth, we treated a polymer substrate with highly dense inductively coupled oxygen plasma. The optical transmittance of the GZOB film, about 80 %, was maintained regardless of the plasma pre-treatment. The resistivity of the GZOB film on PC substrate decreased from 9.08 ${\times}$ $10^{-3}$ ${\Omega}-cm$ without an $O_2$ plasma pre-treatment to 2.12 ${\times}$ $10^{-3}$ ${\Omega}-cm$ with an $O_2$ plasma pre-treatment. And PES substrate decreased from 1.14 ${\times}$ $10^{-2}$ ${\Omega}-cm$ without an $O_2$ plasma pre-treatment to 6.13 ${\times}$ $10^{-3}$ ${\Omega}-cm$ with an $O_2$ plasma pre-treatment.

• Environmental Engineering Research
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• 제12권1호
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• pp.1-7
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• 2007

Most of the herb residue producing from oriental medical clinics(OMC) and hospitals(OMH) is wasted in Korea. To develop of adsorbent for removing heavy metal from wastewater, the various pre-treatment methods of the herb residue were evaluated by potentiometric titration, Freundlich isotherm adsorption test and the kinetic adsorption test. The herb residue was pre-treated for increasing the adsorption capacity by cleaning with distilled water, 0.1 N HCl and 0.1 N NaOH and by heating at $370^{\circ}C$ for 30 min. It showed a typical weak acid-weak base titration curve and a short pH break like commercial activated carbon during photentiometric titration of pre-treated herb residue. The log-log plots in the Freundlich isotherm test were linear on the herb residue pre-treated with NaOH or HCl like commercial activated carbon. The adsorption capacity(qe) in the Freundlich isotherm test for $Cr^{6+}$ was 1.5 times higher in the pre-treated herb residue with HCl than in activated carbon. On the other hand the herb residue pre-treated with NaOH showed the good adsorption capacities for $Pb^{2+}$, $Cu^{2+}$ and $Cd^{2+}$ even though those adsorption capacities were lower than that of activated carbon. In kinetic test, most of heavy metals removed within the first 10 min of contact and then approached to equilibrium with increasing contact time. The removal rate of heavy metals increased with an increase of the amount of adsorbent. Likewise, the removal rates of heavy metals were higher in the herb residue pre-treated with NaOH than in that pre-treated with HCl. The adsorption preference of herb residues pre-treated with NaOH or HCl was $Pb^{2+}>Cu^{2+}$ or $Cd^{2+}>Cr^{6+}$ in the order. Conclusively, the herb residue can be used as an alternative adsorbent for the removal of heavy metals depending on pr-treatment methods.

• 한국식품영양학회지
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• 제16권2호
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• pp.130-137
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• 2003

The squid had not been utilized for gel products because of its lower gel forming ability. The objectives of this study were as followed; 1) the optimum heating condition on squid meat paste products and 2) the optimum added level for jelly strength of squid meat paste products. Optimum heating conditions of squid meat kamaboko were as followed; setting(pre-heating) at 15$^{\circ}C$ or 55$^{\circ}C$ for 2 hours and heating at 9$0^{\circ}C$ for 60 minutes. The additives examined were as follows; 20mM EDTA, 10mM PMSF, 5 $\mu$mol/100g TGase, 0.2% potassium bromate, 2% collagen, 2% sucrose ester of stearic acid and 1% egg shell powder. The effects of additives on jelly strength were observed as follow, in descending order; 10mM of PMSF>5 $\mu$mo1/100g of TGase>0.2% of potassium bromate>20mM of EDTA. But sucrose ester of stearic acid and 1% egg shell powder were no effect. The solvents examined were as follows; n-amyl alcohol, n-butyl alcohol, n-hexyl alcohol, ethyl alcohol, ethylene glycol, propylene glycol and glycerin glycol. It showed that high jelly strength as 787gㆍcm for 3% of n-butyl alcohol and 749gㆍcm for 3% of n-amyl alcohol. To adding 5% of n-butyl alcohol and n-amyl alcohol, gave the highest jelly strength and water holding capacity(WHC). Effect of alcohol on jelly strength appeared higher value at added 5% of n-butyl alcohol than n-amyl alcohol, and flying squid product was higher than jumbo squid product.

• 생명과학회지
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• 제13권4호
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• pp.481-491
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• 2003

A squid meat has not been utilized for gel products because of its lower gel forming ability. The objectives of this study were as followed; 1) the optimum heating condition on squid meat paste products and 2) the optimum added level for jelly strength of squid meat paste products. Optimum heating conditions of squid meat kamaboko were as followed; setting (pre-heating) at 15$^{\circ}C$ or 55$^{\circ}C$ for 2 hours and heating at 90$^{\circ}C$ for 60 minutes. Effect for jelly strength of starch additives wheat starch, potato starch and com starch were examined. The jelly strength of heat induced gels differed from the levels of additives. In case of adding starch, potato starch was resulted in the superior jelly strength than the other starchs, wheat starch and corn starch, at any levels. Optimum concentration was 10%(w/w) at every additives. Folding test value was B at added 10% and this value was mean good product. Data of jumbo and flying squid meat paste products added potato starch, corn starch and wheat starch of 10% were shown below, jelly strengths were 858${\pm}$34∼1020${\pm}$37gㆍcm and 966${\pm}$33∼l148${\pm}$45gㆍcm and moisture contents were 72.43∼73.04% and 71.61∼72.78%, respectively. To adding edible agar and sea tangle, showed the highest jelly strength (edible agar>sea tangle, flying squid>jumbo squid) at added 0.5%(w/w) concentration.

• Journal of Advanced Marine Engineering and Technology
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• 제38권6호
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• pp.688-697
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• 2014

본 연구에서는 최근, 전기자동차 및 소형 레저용 선박을 중심으로 연구가 진행 중인, 대용량 이차전지의 용량 증대를 위하여 필요한 내부 전극 접합 기술에 관하여 연구하였다. 종래의 초음파 용접으로 적층할 수 있는 적층 량의 한계를 극복하기 위한 방안으로 전극 소재에 직접 가열을 통한 용접 방법이 아닌 용가재 금속을 적용하여 전극을 접합시켜, 통전성과 인장강도를 증대시킴과 동시에 열적요인으로 인한 전극표면에 화학적 활성물질의 변성을 최소화 할 수 있는 저온 접합 방법에 대하여 연구하였다. 부연하여 현재 일반적으로 적용되고 있는 초음파 용접 및 저항 용접은 전극을 다량 적층 접합 시켰을 경우 일정한 전기 전도성과 접합 강도를 구현하기 힘들다. 용접을 위하여 무리하게 출력을 상승시킬 경우 용접열의 영향으로 전극의 변형 및 활성물질의 변성을 야기함과 동시에 최종 페키징(packaging) 이후 출력저하, 발열 등, 배터리의 안정성을 저하시키는 요인으로 작용한다. 따라서 본 연구에서는 고주파 유도가열을 통한 유도 가열 방식의 접합 방법과 용융 도금을 통한 용가재 금속의 전처리를 통한 종래와는 차별화된 전극접합 방법을 소개한다.

• 융합신호처리학회논문지
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• 제19권2호
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• pp.61-67
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• 2018

용접예열은 본 용접 전에 금속이 융착되는 모재면을 일정한 온도로 가열하는 것을 의미한다. 냉각속도 조절에 따른 재료 경화 정도 감소, 불순물 편석억제, 열적 변형방지, 그리고 수분제거 등 인접 영향부의 균열을 방지할 수 있다. 이러한 이유에서 고품질의 용접을 위하여 반드시 필요한 작업이다. 유도가열은 전자기유도 현상을 응용하여 전기에너지를 열에너지로 변환시키는 효율적인 가열방식이다. 기체 및 액체를 이용한 연소발열과 비교하여 신속한 가열뿐만 아니라 청결하고, 안정적이며, 경제적이다. 단순한 구조로 주파수와 코일의 형태를 변형하여 가열체의 형상, 깊이, 재질에 관계없이 가열할 수 있다. 본 논문에서는 유도가열 기법을 이용하여 저주파 용접예열 시스템을 구현하였으며, 3종의 자동차 변속기 부품을 대상으로 권선코일 내에서 각 변속기 높이에 따라 권선코일 저항, 인덕턴스 및 자동차 변속기 부품의 온도변화를 관찰한 결과 전류의 변화는 저주파 가열에 있어 매우 중요한 요인으로 작용함을 확인하였다.

• 한국축산식품학회지
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• 제38권5호
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• pp.970-980
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• 2018

We evaluated the effects of pre-cooking methods on the quality of reheated marinated pork loin. Frozen marinated pork loins cooked using various methods (boiling, grilling, pan frying, infrared cooking, and superheated steam cooking) were reheated in a microwave, and their pH, color, cooking loss, re-heating loss, total loss, thiobarbituric acid reactive substance (TBARS) value, sensory properties, and shear force were determined. Although all parameters varied with different cooking methods, lightness values and TBARS values showed the tendency to decrease and increase, respectively, after reheating. Superheated steam-cooked samples showed the lowest values of cooking loss, total loss, TBARS value, and shear force (p<0.05) and the highest lightness, redness, and yellowssness values and juiciness, chewiness, and overall acceptability scores (p<0.05). These results show that pre-cooking with superheated steam maintains the quality characteristics of marinated pork loin upon reheating. Therefore, pre-cooking with superheated steam may be beneficial for the commercial distribution of frozen cooked marinated pork loin.

• 한국해양공학회지
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• 제9권1호
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• pp.101-110
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• 1995

In SMA(Shape Memory Alloy), the degradation by fatigue is one of the most important problems to be overcome, when SMA is used for robot-actuator materials. The actuator is operated repetitively for long time and its repeating operation develops the fatigue degradation of SMA. The fatigue degradation changes the transformation temperature and deformation behavior and results in inaccurate operation and deformation which results form repeating operation is to be investigated in advance and the scheme to resolve those problems have to be made for the design of actuator. In this paper, for the improvement of the fatigue degradation by repetive movement and better control of the correct movement by the stability of martensite transformation in the development of Robots actuator, Pre-strain(0, 1.5, 5, 8%) are loaded in the specimens and fatigue testing were carried out by the method of heating and cooling in direct condition. From the results of these experiments, the effect on pre-strain which affect the transformation characteristic and fatigue degradation phenomena were correctly investigated.

• Journal of the Korean Wood Science and Technology
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• 제47권5호
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• pp.567-578
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• 2019

A common problem with fast-growing hardwoods is dimensional instability that limits use of their wood. In this study, we investigated the effects of pre-drying methods, temperatures, and heating duration on the specific gravity, water absorption, and dimensional stability of three tropical fast-growing hardwoods, jabon (Neolamarckia cadamba Roxb.), sengon (Falcataria moluccana Miq.), and mangium (Acacia mangium Willd.). Wood samples were pre-dried by two methods (fan and oven at $40^{\circ}C$), and heat treatments were performed at three temperatures (120, 150, and $180^{\circ}C$) for two different time periods (2 and 6 hours). The specific gravity, water absorption, dimensional stability, and structural changes of the samples were evaluated. The results revealed that heat treatments slightly reduced the specific gravity of all three wood species. In addition, the heat treatments reduced water absorption and significantly improved dimensional stability of the samples. Oven pre-drying followed by heat treatment at $180^{\circ}C$ for 6 hours resulted in good physical improvement of jabon and sengon wood. Fan pre-drying followed by heat treatment at $180^{\circ}C$ for 2 hours improved the physical properties of mangium wood. The heat treatment shows a promising technique for improving the physical characteristic of fast growing hardwoods.