액상첨가제를 활용한 폴리우레탄 폼의 특성 향상 방안

학위논문 (박사)-- 서울대학교 대학원 : 화학생물공학부, 2017. 2. 한종훈.Polyurethane is a polymer material made by the exothermic reaction between polyol and isocyante. It has many good properties that it has been widely used in various kinds of industry. [1] Especially rigid polyurethane foam is one of best thermal insulation materials and it has been used as a main insulator for cryogenic industries such as Liquefied Natural Gas (LNG) storage tanks, LNG carriers etc. [1-4] Blowing agent is a material which makes polyurethane cellular material and gives polyurethane foam insulating ability. CFCs were typical blowing agents. But they have not been used because they destroy the stratospheric ozone layer. HCFC-141b was chosen for an alternative to CFCs. However, although small ozone depletion potential (ODP) of HCFC-141b compared to CFCs, additional alternative blowing agents with zero ODP such as hydroflurocarbons (HFCs) have been needed because of tougher environmental regulations since 2000s. LNG demand has risen by an estimated 7.5% per year since 2000. [5] Nowadays the price of natural gas has become higher and the efficiency of propulsion systems of liquefied natural gas (LNG) carriers has improved. Due to these trends, required boil-off rate (BOR) has been lowered from 0.15%/day to 0.12%/day for conventional LNG carriers with sizes between 125,000 m3 and 170,000 m3. This requirement of BOR can be satisfied by using a rigid polyurethane foam (PUF) blown by 1,1-dichloro-1-fluoroethane (HCFC-141b) as an insulator but we cannot use it anymore. So new alternative blowing agent should be used instead of HCFC-141b. But the use of alternative blowing agent can make another problem like deterioration of thermal conductivity due to its relatively high thermal conductivity. [1, 3, 6-12] This research introduces HFCs as an alternative to HCFC-141b and discuss characteristics of rigid PUFs prepared with HFCs and shows its application to LNG carriers. We also discuss effects of liquid-type additives to enhance properties of rigid PUFs under laboratory atmosphere and the possibility of their adaptability to mass production type PUFs. For these three liquid-type additives, propylene carbonate (PC), perfluoroalkane (PFA), and acetone, were introduced. The addition of perfluoroalkane induced the small cell size of the PUFs. Based on the morphology, thermal conductivity, and compressive strength, it is suggested that the perfluoroalkane is an efficient liquid-type additive for the improving the thermal performance of PUFs. [13, 14] Based on this result, a mass production type rigid PUF for a LNG carrier was manufactured and evaluated for BOR, mechanical strengths over operation temperature range, coefficient of thermal expansion (CTE), and thermal shock stability for LNG carriers. The calculated BOR of the manufactured rigid PUF is below 0.12%/day, which satisfies the recent and tough BOR specification for LNG carriers. Other properties also meet the specifications for a conventional LNG carrier. [13] Consequently, it is expected that the results in this paper will bring low BOR (<0.12%/day) LNG carries with rigid PUFs using ODP free blowing agents and contribute environmental protection through saving energy and preserving the ozone layer in the stratosphere. Besides that, the product of this paper will reduce the time required to construct the raw material system and make the blending system configuration process easier.CHAPTER 1 : Introduction 1 1.1. Research motivation 1 1.2. Trend in blowing agent selection and checking the effect of various additives on properties of polyurethane foam 6 1.3. Research objectives 10 1.4. Outline of the thesis 11 CHAPTER 2 : Effect of Liquid-Type Additives on Properties of Polyurethane Foam 12 2.1. Introduction 12 2.2. Factors to affect properties of polyurethane foam 14 2.3. Experiment 20 2.3.1. Materials 20 2.3.2. Preparation of polyurethane foams 22 2.3.3. Measurement and experimental conditions 24 2.4. Effects of additives on properties of polyurethane foam 29 2.4.1. Blowing agent on rigid PUF performance 31 2.4.2. Propylene carbonate on rigid PUF performance 34 2.4.3. Effects of acetone on rigid PUF performance 37 2.4.4. Effects of perfluoroalkane on rigid PUF performance 40 2.5. Conclusion 44 2.5.1. Surface tension of polyol solutions 44 2.5.2. Cell size of PUF 47 2.5.3. Thermal Conductivity of PUFs 50 2.5.4. Compressive Strength of PUFs 53 CHAPTER 3 : Construction of Blending System for Commercial Mass Production Type PUF 57 3.1. Introduction 57 3.2. Blending system for mass production type polyurethane foam 60 3.3. Conclusion 65 CHAPTER 4 : Evaluation and Confirmation of the Possibility of Using the Mass-produced Polyurethane Foam Insulation for a LNG Carrier 66 4.1. Introduction 66 4.1.1. Heat transfer in conjugated membrane type insulation panel 69 4.1.2. Calculation of boil-off rate in LNG carrier 73 4.2. Measurement and experimental conditions 74 4.3. Evaluation results 81 4.3.1. Mechanical strength characteristics 81 4.3.2. Thermal conductivity characteristics 84 4.3.3. Thermal stability characteristics 86 4.4. Lifetime Evaluation of Polyurethane Foam 88 4.5. Economics 93 4.6. Conclusion 96 CHAPTER 5 : Concluding Remarks 97 5.1. Conclusions 97 5.2. Future works 99 Nomenclature 100 Literatures cited 102 Abstract in Korean (요 약) 109Docto

An analysis of the relative efficiency and the total factor productivity changes of SMEs in SME funding program

이 연구는 중소기업 정책자금을 지원 받은 기업의 지원 이후 상대적 효율성과 생산성 추이를 측정하고, 종업원 수, 자본금 등 기업규모와 업종 등 기업 특성 변수와 정책자금의 종류, 비중, 규모 등 정책자금 변수를 기준으로 수혜 기업을 집단화하여, 상대적 효율성 및 생산성 추이의 기업 집단간 성과 차이를 통계적으로 분석하였다. 분석 결과, 기업 특성 변수에 있어서는 종업원 수 및 자본금의 규모가 큰 기업일수록 성과 변수와 높은 연관이 있음이 나타났으며, 업종별로는 전기업종에 대한 지원이 다른 업종에 비해 상대적으로 높은 성과와 연관되어 있음을 알 수 있었다. 한편 정책자금 변수와 성과와의 연관성을 보면, 직접대출이 대리대출 방식에 비해, 운전자금 위주의 지원이 시설자금 위주의 지원에 비해, 그리고 지원규모가 클수록 보다 높은 효율성이나 생산성 변화에 연관되어 있음을 알 수 있었다. The objective of this study is to measure the relative efficiency and the total factor productivity(TFP) changes of SMEs funded by Korea government's SME funding program. To do this, we use data envelopment analysis(DEA) and Malmquist productivity index. The results show that the average efficiency score is about 0.49-0.62 and the TFP of the sample is in trend of increasement in the sample years. Further, we relate the results with the characteristics of the firms(such as employment size, capital size, types of industry) and the methods of funding. We find that, in general, the performance of SME funding program is highly related to the larger firms, larger amounts of funding, direct funding rather than indirect funding, and funding for working fund rather than equipment fund.이 논문은 2005년 건국대학교 신임교원연구비 지원에 의한 논문임

전자정부제도 도입(The Introduction of e-Government in Korea)

노트 : 본 보고서는 영문보고서를 축약하여 작성한 것으로 구체적인 내용은 영문보고서를 참고하시기 바랍니다

부유식 해양구조물의 운동응답 및 구조해석

학위논문(석사)--서울大學校 大學院 :造船海洋工學科,1995.Maste

A Comparative Study of the Relationship between Government Regulation and Productivity in OECD countries

현대 정부가 규제의 질을 강조하는 규제개혁을 추진하기 위해서는 정부규제의 경제적 효과에 대한 분석이 선결적 과정이라고 할 수 있다. 그럼에도 불구하고 정부 고유의 강제력에 기반하여 국민 생활과 기업 활동에 개입하는 정부규제의 다양한 유무형의 영향에 대한 효과 측정은 쉽지 않으며, 그 결과에 대해서도 논란의 여지가 많다. 이 같은 어려움 때문에 우리나라의 경우 정부 규제의 경제적 효과를 분석하는 연구가 많지 않은 실정이다. 이러한 맥락에서 이 연구에서는 OECD에서 회원국의 정부규제 구조 및 정책을 주기적으로 파악하는 규제지수 설문조사(Regulatory Indicators questionnaire) 데이터를 활용하여, 각 국의 규제정도와 생산성과의 관계를 분석하였다. 분석은 두 단계로 이루어졌는데, 첫번째 단계에서는 맘퀴스트지수(Malmquist index)를 활용해 각국의 총요소생산성변화(total factor productivity change, TFPC)를 측정하였다. 두번째 단계에서는, 첫번째 단계에서 측정된 생산성변화를 종속변수로 사용하고, OECD 22개 국가를 표본으로 하여 정부규제정도를 지수화한 PMR(product market regulation)지수를 설명변수로 사용하여, 규제의 생산성에의 영향을 실증분석하였다. 분석 결과 첫째, 1998년과 2003년의 두 시점동안 OECD 22개국은 평균 약17%의 총요소생산성 향상이 있었으며, 그 변화의 많은 부분이 기술적 변화(technical change)에 기인하였다. 둘째, 정부규제의 개혁의 정도가 클수록 생산성 증가의 폭이 큰 것으로 나타난 가운데, 다양한 유형의 제품시장에 대한 규 제 중 국외지향적(outward) 규제보다는 국내지향적(inward) 규제가 생산성 변화에 상대적으로 큰 영향을 미치고 있음이 나타났다. One of the hottest topics in the field of regulation is about the effects of government regulation on a nation's productivity. This study empirically investigates the relationship between government regulation and productivity among the OECD countries, utilizing Regulatory Indicators Questionnaire data, collected and provided by the OECD. In a two-step analysis, this paper first analyzes the changes to total factor productivity among OECD countries over the 1998 to 2003 time period, using the Malmquist index method. During the period, the countries showed about a 17% growth rate in productivity, mainly due to technical innovation. In the second step, we analyzed the relationships between government regulation and the productivity growth obtained in the first step. The results indicate that more market-oriented regulatory reforms have positive effects on productivity growth

충남공공디자인 세미나(CNI세미나2017-145)(박성남,이영범)

공공디자인과 도시재생의 연계, 협력 방안 도출 및 충남 공공디자인 활성화를 통한 지역재생 방법론 모색- 개회 및 국민의례 - 인사말씀 (충남연구원장) - 인사말씀 (충청남도 국토교통국장) - 발표 1 (건축도시공간연구소 센터장 - 발표 2 (경기대학교 건축학과 교수) - 토론 (좌장 충남연구원장)