• 한국염색가공학회지
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• 제6권1호
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• pp.33-43
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• 1994

In the present work, to clarify the mechanism of the neutral salt effect on the alkaline hydrolysis of PET, many salts with different cations like LiCl, NaCl, KCl, CsCl were added to the aqueous alkaline solutions. Then PET was hydrolyzed with aqueous solutions of many salts in alkali metal hydroxides under various conditions. Some conclusions obtained from the experimental results were summarized as follows. The reaction rate of the alkaline hydrolysis of PET was increased by the addition of neutral salts and In k was increased nearly linearly with the square root of ionic strength of reaction medium. This fact suggested that the ionic strength effect by Debye-Huckel and Bronsted theory was exerted on the reaction. The specific salt effect was also observed. The reaction rate was increased with the increase in the electrophilicity of cations of neutral salts, i. e., in the order of $Cs^+$/ < $K^+$/ $a^+$/ $i^$^+$. It was considered that the reaction rate was increased in the order of C $s^+$. < $K^+$. $a^+$. $i^+$. because the lowering effect of the cations on the negative charge of PET surface was increased with the electrophilicity of cations. It was thought that $E_{a}$ was increased because the cations of neutral salts decreased the negative charge of PET surface. It, however, was inferred from the increase in ${\Delta}$S＊ and the decrease in the ${\Delta}$G＊ that the cations of neutral salts associated with PET increased the collision frequency between carbonyl carbon and OH- ion and then accelerated the reaction rate.te.

• 한국염색가공학회지
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• 제7권4호
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• pp.61-73
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• 1995

Inorganic salts have negative or positive effects on the rates of many chemical reactions and also the rates of acidic and alkaline hydrolysis of carboxylic esters. The direction of salt effects on the hydrolysis of ester depends on the charge of esters. It is expected that the rate of the alkaline hydrolysis of Poly(ethylene terephthalte)(PET), polymeric solid carboxytic polyester with carboxyl end group at the polymer end, is also influenced by inorganic salts. In the present work, to clarify the effect of divalent cations on the alkaline hydrolysis of PET, many salts with divalent cations like $MgCl_{2},CaCl_{2},SrCl_{2},BaCl_{2},$ were added to the aqueous alkaline solutions. Then PET was hydrolyzed with aqueous NaOH solution having many salts under various conditions. Some conclusions obtained from the experimental results were summarized as follows. Many salts with various divalent cations increased or decreased the reaction rate of alkaline hydrolysis of PET depending on their electrophilicity, hydration property, ability of ion pair formation, solubility, and the degree of interactions between divalent cations and anions, etc. The hydrolysis was interrupted in the order of $Ca^{+2} and was generally accelerated in the order of $Ba^{+2}. It was inferred from the increase in ΔS$^*$and the decrease in the ΔG$^*$that the divalent cations $Sr^{+2}$ and $Ba^{+2}$attracted by PET increased the collision frequency between carbonyl carbon and $OH^{-}$ion and then accelerated the reaction rate. $Mg^{+2}$and $Ca^{+2}$decreased the reaction rate because of their strong interaction with $OH^{-}$.

• 한국산학기술학회논문지
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• 제17권10호
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• pp.54-60
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• 2016

BIM은 단일모델을 이용해 다양한 시나리오로 활용 가능하다는 이점이 있다. BIM 모델을 통해 2D 도면을 자동으로 추출하는 점도 그 중의 하나이나, 이를 실무에서 그대로 활용하기에는 현실적으로 어려움이 따른다. 건축 상세도면은 실내재료 마감 및 복잡한 시공방법을 표현할 뿐 아니라 공사비 산정에 있어 매우 중요한 요소이다. 하지만 이를 BIM 환경에서 표현하는 공통적인 규칙이나 약속이 없고, 설계사별로 같은 의미의 상세도면을 각기 다른 형태로 보유하고 있어 건설산업차원에서의 정보공유 및 교환을 어렵게 한다. 따라서 본 연구에서는 건축 상세도면의 BIM 활용을 위해 부분상세 정보를 체계화하는 방법을 제시하고, BIM 라이브러리와 어떻게 연계되어 수량 및 공사비 산정의 기초자료로 활용되는지 파악한다. 본 연구는 건축 설계자가 설계 업무 진행시 BIM 라이브러리를 통하여 부분상세정보를 확인하고 단가정보, 자재정보 등과 연계되어 수량 및 공사비를 산출하는데 활용될 수 있다. 또한 BIM 라이브러리-기술콘텐츠 연계기술로 인해 BIM기반의 설계효율과 프로세스를 개선해 중소설계사무소의 효율적인 BIM 활용에 도움이 될 것이다.

• 한국산학기술학회논문지
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• 제20권3호
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• pp.56-64
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• 2019

공동주택 하자는 추가적으로 투입되는 각종 자원의 낭비, 경제적 비용손실로 연결되며, 입주자들에게는 시간적, 물질적, 정신적 피해를 주고, 기업에게는 금전적인 손실뿐만 아니라 기업 신용도를 추락하는 문제를 발생시킨다. 이러한 관점에서 본 연구에서는 다수의 하자분쟁 사례를 활용하여 공동주택 공종/하자유형/부위에 대하여 하자 빈도 및 심각도를 고려한 중요도를 산출하여 공동주택 하자관리 효율성을 제고하고, 하자분쟁을 최소화하는데 기여하고자 한다. 이를 위하여 본 논문에서는 공동주택 하자분쟁사례 48건, 약 7,548개의 하자항목 자료를 토대로 분석을 실시하였다. 분석 결과를 정리하면, 하자가 주로 발생하는 공종은 RC, 마감, MEP 공종이며, 중요도가 높은 하자유형은 균열, 누수, 오시공, 미시공 등인 것으로 확인되었다. 또한 하자부위의 경우 상대적으로 현장 설치 중심의 가구, 설비기기보다 현장 시공 중심의 외벽, 내벽, 내부 천장 및 바닥이 하자 중요도가 높은 것으로 확인되었다. 이에 따라 기본적으로 생애주기 각 단계별 품질관리를 철저히 할 필요도 있지만, 내부공간을 구성하는 부위의 경우, Pre-fabrication에 대한 활용성을 높이는 것을 고려할 필요가 있다.

• 한국염색가공학회지
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• 제34권1호
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• pp.68-75
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• 2022

The breathable film refers to a high-functional film that allows gas and water vapor to pass through very fine and sophisticated pores but not liquid. In this research, the breathable film was prepared based on linear low-density polyethylene (LLDPE) and CaCO₃ particles by extrude method. The LLDPE composite film containing CaCO₃ particles had excellent mechanical properties and functionalties. The drawing is a technologically simple and excellent method for improving the mechanical properties of composite films. In this work, the effects of draw ratio on morphology, crystallinity, pore size distribution, mechanical properties, and water vapor permeability of the films were examined. The results revealed that both surface morphology and breathability were affected by the influence of chain orientation and crystal growth with increasing the draw ratio. The mechanical properties were improved with increasing the draw ratio.

• 산업경영시스템학회지
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• 제45권4호
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• pp.157-166
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• 2022

In the case of a die-casting process, defects that are difficult to confirm by visual inspection, such as shrinkage bubbles, may occur due to an error in maintaining a vacuum state. Since these casting defects are discovered during post-processing operations such as heat treatment or finishing work, they cannot be taken in advance at the casting time, which can cause a large number of defects. In this study, we propose an approach that can predict the occurrence of casting defects by defect type using machine learning technology based on casting parameter data collected from equipment in the die casting process in real time. Die-casting parameter data can basically be collected through the casting equipment controller. In order to perform classification analysis for predicting defects by defect type, labeling of casting parameters must be performed. In this study, first, the defective data set is separated by performing the primary clustering based on the total defect rate obtained during the post-processing. Second, the secondary cluster analysis is performed using the defect rate by type for the separated defect data set, and the labeling task is performed by defect type using the cluster analysis result. Finally, a classification learning model is created by collecting the entire labeled data set, and a real-time monitoring system for defect prediction using LabView and Python was implemented. When a defect is predicted, notification is performed so that the operator can cope with it, such as displaying on the monitoring screen and alarm notification.

• 현장농수산연구지
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• 제10권1호
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• pp.169-181
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• 2008

The purpose of this study was to produce Pleurotus ostreatus using fermenter with bag cultivation. These results are as follows. 1. While mushroom composts were being fermented in a fermenter, the physical property of the fermented composts was getting better when there isn't any screw or revolving flies in the fermenter and the strength of pressing the composts was getting less. 2. The composts were fermented well as slaked lime of 1% density added to the composts. 3. According to the result of examining our fermenting ways, composts were in the best condition after being fermented for 48 hours since the temperature in a fermenter has come to 60℃, which could be reached by heating the fermenter by 40℃ after putting compost materials and water into it. 4. The good condition of fermenting could be maintained by controlling the speed of revolving flies, therefore the speed be down when the temperature is above 60℃ and up bellow 60℃. 5. Since the composts had been added with 1.5~2% of cottonseed meal or rice bran, the fermented composts were in good condition and also the quantity and quality of the mushroom produced on the fermented composts were satisfied. 6. There were needed 7 hours of labour for 3days from the first day of putting composts into a fermenter for fermenting 3.5M/T(10,000~12,000bags of 750~800g per bag) of composts to the third day of finishing the fermenting work, and also the cost was 112,066￦(130$) including 52,066￦(60$) of electric charge and fuel expense.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.339-343
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• 2015

To rapidly recover ceased functionality of a facility after a catastrophic seismic event, critical decisions on facility repair works are made within a limited period of time. However, prolonged damage assessment of facilities, due to massive damage in the surrounding region and the complicated damage judgment procedures, may impede restoration planning. To assist reliable structural damage estimation without a deep knowledge and rapid interactive analysis among facility damage and restoration operations during the approximate restoration project planning phase, we developed a prototype of distributed facility restoration simulations through the use of high-level architecture (HLA) (IEEE 1516). The simulation prototype, in which three different simulations (including a seismic data retrieval technique, a structural response simulator, and a restoration simulation module) interact with each other, enables immediate damage estimation by promptly detecting earthquake intensity and the restoration operation analysis according to estimated damage. By conducting case simulations and experiments, research outcomes provide key insights into post-disaster restoration planning, including the extent to which facility damage varies according to disaster severity, facility location, and structures. Additional insights arise regarding the extent to which different facility damage patterns impact a project's performance, especially when facility damage is hard to estimate by observation. In particular, an understanding of required type and amount of repair activities (e.g., demolition works, structural reinforcement, frame installation, or finishing works) is expected to support project managers in approximate work scheduling or resource procurement plans.

• 한국건축시공학회지
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• 제23권5호
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• pp.571-581
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• 2023

최근 국내 건설산업은 건설업체의 경영난과 물량 감소로 인해 위축되고 있다. 국내 건설사들은 건설시장에서의 경쟁 우위 확보를 위해 모든 공종에 대해 원가절감 및 품질향상을 위한 노력을 기울이고 있다. 가치공학(VE) 기법은 건축공사에서 원가절감뿐만 아니라 공기 단축과 품질향상을 위한 도구로 활용되는데, 골조 공사 분야에 적용되는 성과가 상대적으로 미미한 실정이다. 공장 건설에서 골조 공사는 전체 공정에 큰 영향을 미치는 주요 공정이므로 골조 공사 계획단계에서 VE 기법을 도입해 설계도서와 현장 여건을 분석하여 품질과 안전을 확보하면서 공사 기간 단축, 원가절감, 작업성을 높일 수 있는 대안을 개발할 필요가 있다. 본 연구는 공기 단축, 원가절감, 시공 안전성 확보를 위한 기초연구가 될 것으로 기대된다.

• 공업화학
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• 제2권2호
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• pp.175-184
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• 1991

PVC 와 Polystyren 과 같은 고분자가 자외선에 노출될 때 이들 표면을 보호하고, 물성을 유지하기 위해서 자외선 경화 도료를 도장하지만, PVC 는 epoxy acrylate 에 대해서, 그리고 Polystyren 은 대부분의 UV도료에 부착력이 약하므로, 반응희석제의 조성을 변화시키거나, 다관능기 acrylate를 표면에 photografting 시키거나, 표면을 광화학적으로 활성화시켜 부착력을 향상시킴을 목적으로 하였다. 미리 침투시킨 광개시제에 의한 grafting이나 표면 활성화로 부착력은 현저히 증가하였고, 각 희석제에 있어 Tripropylene glycol diacrylate는 유연성 향상과 부착력 증가를 가져오나, 황변 현상과 표면 산화에 의한 경화 밀도의 증가로 grafting을 제외한 다른 도장 방법은 시간이 지남에 따라 도막의 부착력이 감소하였다. 여기에 비해 Trimethylol propane triacrylate 는 원래 다관능기에 의해 높은 경화 밀도를 가지고 이에 따른 단단한 도막 때문에 부착력에 문제가 있으나, 두가지 도장법에서는 오히려 다관능기에 의한 화학 결합으로 부착력이 향상되었다. 그리고, 고분자 표면의 표면 에너지를 활성화를 통해 증가시킴으로 해서 UV 도료의 상용성 문제를 grafting 과 표면 활성화를 통해 해결해 도료 배합의 다양화와 기능화를 가져올 것이 기대된다.