금속부식억제 특성 분석을 위한 온라인 부식율 측정 시스템 연구

박말용 韓國産業技術大學校 2016 국내박사

ABSTRACT Study of an On-line Corrosion Rate Measurement System for Analysis on the Corrosion Inhibition Characteristics by Park, Mal-yong Advisor : Prof. Kang, Dae-Jin, Ph.D. Course for Energy( Intelligent Control System ) Graduate School of Knowledge-based Technology and Energy Korea Polytechnic University· The corrosion rate measurement method of Water Treatment system was developed using a PC, a data acquisition board with a relevant software program and a 2-electrode corrosion probe. With the proposed IT Convergence Technology System, the corrosion inhibition characteristics of sodium nitrite were studied for iron and aluminum brass Structure submerged in corrosive water solution. Corrosion rate was measured based on the linear polarization resistance change. The corrosion rate of aluminum brass was measured higher than that of iron in chloride containing water. Although the corrosion rate of iron in 1% NaCl water soultion was measured to be 0.2134 mmpy (mm per year) which is rather high it could be reduced to less than 0.0254 mmpy with the inhibitor addition of 200 ppm with NO2-. We also proved that the sodium nitrite was a more effective corrosion inhibitor for iron than for aluminum brass. The proposed measurement system can be used in the industrial environments where the corrosion are taking place. Since the systems themselves are exposed to the harsh environments. The accuracy and easiness of the system control will contribute to the related industries. Key words : On-line Corrosion Rate Measurement, Iron, Aluminum Brass, Choride Ion, Sodium Nitrite, Corrosion Inhibition. 국 문 요 약 금속부식억제 특성 분석을 위한 온라인 부식율 측정 시스템 연구 박 말 용 지도교수 : 강 대 진 로봇 · 지능 제어 시스템 한국산업기술대학교 지식기반기술·에너지대학원 온라인 부식감시기술이 애용되고 있는 현실을 반영하여 산업현장에서 적용하기 쉬운 새로운 방식의 온라인 부식율 측정 시스템을 개발하였다. 제안한 측정 시스템은 현장이나 실험실에서 쉽게 구할 수 있는 자료취득 보드와 PC를 이용하여 2채널이 동시에 부식율 측정이 가능한 온라인 부식율 측정 시스템이다. 측정 시스템의 정확도는 메타 프루브(Meta Probe)를 이용하여 검증하였다. 검증 결과, 부식율 측정 범위 0.54 mmpy 이내에서 오차 한도는 측정값의 1% 이내인 것으로 확인되었다. 기존 상용화 되어있는 측정계측 방식으로 측정한 결과들은 본 연구에서 개발한 시스템보다 측정 오차가 더 큰 것으로 확인되었다. 억제제에 대해 자세히 설명한 이유는 총정리하는 의미와 사용할때 주의점을 명세하기 위해서 이다. 본 연구에서 개발한 온라인 부식율 측정시스템을 이용하여 철(Fe)과 알루미늄황동(Al-Brass)에 대한 아질산나트륨(Sodium Nitrite)의 부식억제 특성을 조사하였다. 조사 결과, 부식성 이온이 함유된 수용액에서 알루미늄 황동의 부식율은 철에서 보다 더 높은 것으로 확인되었다. 염소이온 농도가 높은 수용액에서는 철의 부식율이 크게 증가하기 때문에 부식억제제의 주입이 필요하다. 1% NaCl 수용액에서 철의 부식율는 0.2134 mmpy로 매우 높지만 부식억제제인 아질산나트륨을 아질산이온 농도로써 200 ppm 이상 처리할 경우 철의 부식율을 0.0254 mmpy 미만으로 유지할 수 있음을 확인하였다. 또한 연속 제어시스템을 연구개발 하므로 산업현장에서 부식관리 하는데 소중한 자료가 되리라 사려된다. Key words : On-line Corrosion Rate Measurement, Sodium Nitrite, Corrosion Inhibition.

初等學校 第 6, 7次 敎育課程의 比較 硏究

박말용 大邱가톨릭大學校 敎育大學院 2001 국내석사

The seventh curriculum has been partly put into practice beginning the year 2000 to meet the changing waves of the globalism and information age of the twenty-first century. The seventh curriculum is an epoch-making reform, but has brought up a lot of problems in practice. Accordingly, in this research, concepts and types of the curriculum and the changes of the elementary school curriculum were examined first to deepen the understanding of the curriculum. This research has been done to be helpful to the effective operation of the seventh curriculum through the comparison between the present sixth and the revised seventh curriculum and the good grasping of the merits and demerits of them. To achieve this goal, the literature research method of analyzing various materials such as theses and reference books related to this purpose was applied to this study. Our country's curriculum has been revised several times to achieve the harmonious development of all-round education to meet the changes of the times, keeping pace with the philosophical and social demands, Every revision has made a great contribution toward a better education, but still raised a lot of problems. The current 6th curriculum is the one that is changed from the 'centralized curriculum' to the 'decentralized curriculum' for the first time in our education history, but it is revised because it still has various problems. The merits of the 7th curriculum over the 6th curriculum which are derived from the comparison and analysis of the two are as follows. First, the 6th curriculum has the knowledge-oriented, uniform quality of education and method, while the 7th one is the practice-oriented, diverse education and the learning through discussion. Second, The 7th curriculum can enlarge the discretion activity and establish the open education system better than the 6th does. Third, compared with the 6th, the 7th is able to reduce the students' learning burden and enlarge the subject structure gradually. Fourth, the 7th is the optimization of the learning contents and the adjustment of the learning standard. Fifth, the 7th is the alteration of the names of subjects and their fields. Sixth, the 6th is the integration of concepts among subjects, while the 7th is the establishment of the concept of integrated subjects. Finally, compared with distinctive qualities of the two curriculums, the 6th is the school-centered curriculum that gets out of the standardization, while the 7th is the leveling curriculum and can be regarded as the completely consumer-centered curriculum in response to the individuals' demands. But in the following respects, there is the criticism that 7th is not so good as the 6th. First, in fact, in the constructionist view, our country's 7th curriculum is being criticized for its backward movement form the 6th curriculum. It may be thought that the 7th curriculum is presenting another standardized curriculum under the name of the leveling curriculum. Second, the 7th is not suitable for our actual circumstances. Third, the leveling curriculum, in the long run, may widen the difference in the students' levels more than the 6th curriculum did, and bring out more serious problems in the psychological and emotional behavior. However, considering that the 7th curriculum is already being in force, the practical merits and demerits of the curriculum should be discovered, and then the best way to overcome the demerits and maximize the merits should be found. Therefore, the following is to be suggested. First, teachers must improve their abilities to develop the curriculum. Second, there must be continuous research, development and supply of the efficient and proper teaching-learning materials. Third, an expert research institution must do the preparatory research and present the concrete method of applying the 7th leveling to classes, Fourth, the number of the students in each class must be reduced. Fifth, the finance for education must be secured and there must be administrative support. Finally, those concerned with education must have in advance more active recognition and attitude in order to solve the curriculum problems.

이산화탄소 열펌프용 세관 열교환기내 증발열전달의 특성에 관한 연구

박말용 동명대학교 대학원 2020 국내석사

Because of the ozone layer depletion and global warming, new alternative refrigerants are being developed. Among them, HFC refrigerants are thought promising, but some European countries are arguing that these refrigerants are also harmful to the global warming. Therefore, natural refrigerants should be considered as an eventual alternative in refrigerators and heat pumps. In recent years, because carbon dioxide(CO2) naturally exists in the atmosphere and has favorable thermophysical properties, it is suitable for the replacements of the conventional refrigerants. Besides, CO2 is compatible with a compact and small sized heat exchanger, since it has a higher volumetric heat capacity and a lower pressure drop. In this paper, the heat transfer characteristics during the evaporation process of CO2 in a horizontal tube were investigated experimentally. The experiments of the evaporation of CO2 were as follows ; the overall experiments were conducted without oil in the refrigerant loop. The main components of the refrigerant loop are a receiver, a variable speed liquid circulating pump, a mass flowmeter, a preheater, test sections for the evaporation. The experiments were divided into tests, for the evaporator. The test sections of the evaporation process were made of a copper tube with the inner diameter of 4.57mm. The length of the tube is 4,200mm. The evaporators were provided with heat by a direct heating method. The experiments of the evaporation process were conducted at saturation temperatures of -5 to 5℃, heat fluxes of 10 to 40kW/m2 and mass fluxes of 200 to 500kg/m2・s. The main results of evaporation process of CO2 were summarized as follows ; at low quality, the coefficient of evaporation heat transfer increased as vapor quality increase due to domination of nucleate boiling. But, at high quality, the heat transfer coefficient had a tendency to decrease with quality. The evaporation heat transfer coefficients calculated in the experimental data of CO2 were compared with the several existing correlations. All of the existing correlations for the heat transfer coefficient underestimated the experimental data. However Jung et al.'s correlation showed a good agreement with the experimental data in the evaporator of inner diameter tube of 4.57 mm. 열펌프 기기의 보급으로 인한 에너지 절약문제와 다양한 용도로 사용되어 왔던 프레온계 냉매에 의한 심각한 오존층파괴 및 지구온난화 문제에 직면하게 되었다. 이러한 문제들을 해결하기 위해, 에너지소비를 줄일 수 있는 고성능 열펌프기기의 개발과 각종 환경문제를 동시에 해결할 수 있는 연구가 필요하다. 그 해결방법으로 친환경적인 자연냉매를 적용한 고성능 열펌프기기를 개발하는 것이다. 그 중 열펌프의 중요 구성요소인 열교환기의 고성능화, 소형화할 수 있는 열펌프용 세관열교환기 개발과 자연냉매인 이산화탄소(R-744, CO2)는 오존층파괴와 지구온난화에 미치는 영향이 매우 작으며, 독성 및 가연성이 없다. 또한, 냉동기유 및 기기 재료와 호환성이 좋고, 안전성이 뛰어나며, 더욱이 CO2는 기존 냉매들에 비해 높은 비열과 체적열용량을 가지고 있어, 작동온도 범위에서 작동압력이 높은 냉매로서 탁월한 열역학적 물성을 가지고 있으므로 CO2 열펌프시스템을 컴팩터화할 수 있다. 본 연구에서는 증발기에서의 열전달 특성을 파악하는 것은 필수적이다. 이산화탄소 열펌프시스템의 중요 구성요소인 증발기의 열전달계수를 측정하기 위해 수평세관내 4.57mm의 동관을 사용한 시험부를 구성하였고 증발열전달계수에 가장 영향을 미치는 냉매의 질량유속과 외부에서 냉매에 가해지는 열유속이다. 질량유속은 200kg/m2・s에서 100kg/m2・s씩 증가하여 500kg/m2・s으로 변화시키고, 열유속은 10kW/m2에서 10kW/ m2씩 증가하여 30kW/m2까지 변화시키고, 또한 냉매의 포화온도는 -5, 0, 5℃까지 3가지 조건과 입출구의 건도는 0~100%의 조건으로 변화시켜 실험한 내용을 측정하였다. CO2를 이용한 열펌프시스템용 증발기의 최적설계를 위해서 내경 4.57mm관내 CO2 냉매의 증발과정 중에 열전달특성에 대해서 실험 및 타연구자와 검토한 결과, 다음과 같은 결과를 얻었다. 저건도 영역에서는 핵비등이 지배적이기 때문에 증발열전달계수는 약간 증가하고, 강제대류비등이 지배적인 고건도 영역으로 갈수록 증발 열전달계수는 감소하는 경향을 나타내었다. 그리고 수평세관내 CO2의 증발열전달에 대한 실험결과를 Shah, Gungor-Winterton, Kandlikar, Jung 등, Liu-Winterton에 의해서 제안된 상관식과 비교한 결과, 상관식으로 예측한 값이 실험값보다 낮게 나타났으며 Jung 등의 상관식이 평균오차 16.5%로 가장 근사한 일치를 보였다.

CIS(CMOS Image Sensor) 픽셀 構造 硏究 : PPS(Passive Pixel Sensor)와 ASP(Active Pixel Sensor)에 대하여

박말용 고려대학교 공학대학원 2007 국내석사

本 論文에서는 먼저 카메라에 많이 사용되는 CCD(Charge Coupled Device)와 CIS(CMOS Image Sensor)의 特性을 각각 알아 본 후 比較함으로써 이미지 센서에 대한 理解를 넓히는데 도움이 되고자 한다. 이 후, 크게 受動形 픽셀 센서 (PPS, Passive Pixel Sensor) 와 能動形 픽셀 센서 (APS, Active Pixel Sensor)로 나뉘는 CIS 에 관하여 깊이 있게 연구하였다. 硏究 項目으로는 각각의 構造와 동작, 長短點이 있으며 能動形 픽셀 센서의 경우 센서부분이 photogate로 이루어진 구조의 동작에 대해서도 살펴봤고, 마지막으로 분석 된 두 가지 픽셀 센서 구조의 特性을 비교함으로써 어떤 구조가 어떤 特性面에서 優位를 점하고 있는지 알아보았다.