• Nuclear Engineering and Technology
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• v.25 no.2
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• pp.204-214
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• 1993

Work on fracture mechanics has provided a technical basis for elimination of main coolant loop double ended guillotine breaks from the structural design basis of reactor coolant system. Without main coolant loop pipe breaks, the tributary pipe breaks must be considered as design bases until further fracture mechanics work could eliminate some of these breaks from design consideration. This paper determines the core support barrel shell responses for the 3 inch pressurizer spray line nozzle break which is expected to be the only inlet break remaining in the primary side after leak-before-break evaluation is extended to smaller size pipes in the near future. The responses are compared with those due to 14 inch safety injection nozzle break and main coolant loop pipe break. The results show that, when the leak-before-break concept is applied to the primary side piping systems with a diameter of 10 inches or over, the core support barrel shell responses due to pipe breaks in the primary side are negligible for the faulted condition design.

• Corrosion Science and Technology
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• v.14 no.5
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• pp.213-217
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• 2015

Recently, household electronic industries require environmentally-friendly and highly functional steels in order to enhance the quality of human life. Customers especially require both excellent corrosion and abrasion resistant anti-fingerprint steels for digital TV panels. Thus POSCO has developed new functional electro-galvanized steels, which have double coated layers with organic-inorganic composites on the zinc surface of the steel for usage as the bottom chassis panel of TVs. The inorganic solution for the bottom layer consists of inorganic phosphate, magnesium, and zirconium compounds with a small amount of epoxy binder, and affords both improved adhesion properties by chemical conversion reactions and corrosion resistance due to a self-healing effect. The composite solution for the top layer was prepared by fine dispersion of organic-inorganic ingredients that consist of a urethane modified polyacrylate polymer, hardener, silica sol and a titanium complex inhibitor in aqueous media. Both composite solutions were coated on the steel surface by using a roll coater and then cured through an induction furnace in the electro-galvanizing line. New anti-fingerprint steel was evaluated for quality performance through such procedures as the salt spray test for corrosion resistance, tribological test for abrasion resistance, and conductivity test for surface electric conductance regarding to both types of polymer resin and coating weight of composite solution. New composite coated anti-fingerprint steels afford both better corrosion resistance and abrasion properties compared to conventional anti-fingerprint steel that mainly consists of acrylate polymers. Detailed discussions of both composite solutions and experimental results suggest that urethane modifications of acrylate polymers of composite solutions play a key role in enhanced quality performances.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.259-264
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• 2009

Most of the fossil power plants firing lower grade coals are challenged with maintaining good combustion conditions while maximizing generation and minimizing emissions. In many cases significant derate, availability losses and increase in unburned carbon levels can be attributed to poor combustion conditions as a result of poorly controlled local fuel and air distribution within the boiler furnace. The poor combustion conditions are directly related to the gas flow deviation in upper furnace and convection tube-bank but a less reported issue related to in large-scale oppose wall fired boilers. In order to develop a on-line combustion monitoring system and suggest an alternative heat flux estimation method at tube bank, which is very useful information for boiler design tool and blower optimizing system, field test was conducted at operating power boiler. During the field test the exhaust gases' temperature and tube metal temperature were monitored by using a spatially distributed sensors grid which located in the boiler's high temperature vestibule region. At these locations. the flue gas flow is still significantly stratified, and air in-leakage is minimal which enables tracing of poor combustion zones to specific burners and over-fire air ports. Test results showed that the flue gas monitoring method is more proper than metal temperature distribution monitoring for real time combustion monitoring because tube metal temp. distribution monitoring method is related to so many variables such as flue gas, internal flow unbalance, spray etc., Heat flux estimation at the tube bank with flue gas temp. and metal temp. data can be alternative method when tube drilling type sensor can't able to use.

• Membrane Journal
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• v.15 no.4
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• pp.330-337
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• 2005

Water selective silica membranes were prepared fur use as membrane reactor for synthesis of dimethyl ether (DME) by methanol dehydration. Silica membranes formed on a Porous SUS tube by ultrasonic spray Pyrolysis (USP) and chemical vapor deposition (CVD) using tetraethoxysilane (TEOS) as precursor. The CVD-derived membranes formed higher level of trade-off line between water permeance and water/methanol selectivity than that of the USP-derived membranes. The membrane reactor possessing water permeance of $1.2\times10^{-7}\;mol\;{\cdot}\;m^{-2}\;{\cdot}\;S^{-1}\;{\cdot}\;Pa^{-1}$ and water/methanol selectivity of 10 exhibited increase in methanol conversion of about $20\%$ comparing to conventional reactor system. These findings led us to conclude that the dehydration membrane reactor simultaneously separating the water vapour produced in the reaction zone was effective in increasing the reaction conversion.

• Journal of Rhinology
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• v.25 no.2
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• pp.103-107
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• 2018

Pregnancy rhinitis is a relatively common condition. It is characterized by the presence of nasal symptoms, especially nasal congestion, not present prior to pregnancy, but typically present during the last 6 or more weeks of pregnancy, without other signs of respiratory tract infection or any known allergic causes, and disappearing completely within 2 weeks after delivery. Nasal saline irrigation, intranasal steroid spray, and oral antihistamines are usually recommended as the first line of treatment for rhinitis. However, most pregnant women refuse medical treatment for pregnancy rhinitis because of the fear of teratogenicity. Severe pregnancy rhinitis increases the risk of snoring, which has been suggested as having adverse effects on the fetus. In cases where the patients are unable to control their symptoms, pregnancy rhinitis can negatively affect the quality of life (QOL) as well as the pregnancy outcome. Therefore, special caution is required for determining the appropriate diagnosis and treatment modalities for pregnancy rhinitis. Here, we report for the first time, the successful treatment of pregnancy rhinitis that was unresponsive to conservative management and medical therapy by using microdebrider-assisted inferior turbinoplasty at the final stages of pregnancy, along with a review of the relevant literature.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.124-124
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• 2018

Polydopamine은 수중 접착력, 친환경 접착제, nanoparticle absorption 등 다양한 특성으로 많이 연구되고 있는 소재이다. 본 연구에서는 dopamine을 이용하여 수중 금속을 흡착시키는 thin film을 제작하였다. 종래의 Polydopamine coating 방법으로 wet coating 이 사용되고 있다. 하지만 wet 방식의 경우 시간이 오래 걸릴 뿐만 아니라 in-line, roll to roll 방식을 적용하는 것이 어렵기 때문에 생산적이지 않다. 이에 본 연구에서는 Atmospheric Pressure Plasma(APP)를 이용 하여 Polydopamine-like film을 coating 하였다. APP의 경우 vacuum system, solution tank가 필요 없고 in-line, roll to roll 방식을 적용 할 수 있기 때문에 더 경제적이고 생산적인 공정이다. 또한 기존의 Plasma polymerization 방법은 Plasma energy가 높기 때문에 source의 분자구조가 바뀌거나 atom 단위로 분해된다. source의 분자구조가 바뀌는 "Atomic polymerization", Neiswender-Rosskamp Mechanism이 적용되면 wet 방식 coating한 film과는 다른 특성을 갖게 된다. 하지만 APP polymerization은 Plasma energy가 vacuum plasma 보다 매우 낮기 때문에 stile polymerization mechanism을 구현 하는데 적합 하다. stile polymerization mechanism은 Plasma 내부에서 polymer source를 분해 성장 시켜서 Polymer film 얻는 것이 아닌 source의 분자구조가 깨지지 않으면서 polymer growing 시키는 방법이다. dopamine source의 분자구조를 최대한 유지하려고 하는 이유는 metal absorption과 같은 특성이 dopamine chemical structure에 영향을 받기 때문이다. 많은 논문들에서 dopamine의 catechol group이 metal absorption, adhesion force에 영향을 주는 주요 인자라고 주장하고 있기 때문이다. 그래서 본 논문에서는 Dopamine source의 형태를 보존하면서 Polymerization 하는 방법으로 APP process를 사용 하여 낮은 전압에서 Polydopamine-like film을 제작 하였다. APP system 의 Plasma 방전부 에 Dopamine source를 유입하기 위하여 본 논문에서는 Piezo Spray 방식을 사용 하였다. Dopamine을 evaporator 하는 것이 어렵고 chemical composition이 유사한 monomer를 사용해서 Plasma Polymerization으로 Dopamine 분자 구조를 재현하는 것도 어렵다. 그래서 본 연구에서는 Dopamine을 water에 immerse 하고 Dopamine solution을 mist 상태로 만들어서 Plasma discharge area에 유입하였다. 이러한 방법으로 만들어진 film은 Polydopamine film은 아니지만 Polydopamine film과 유사한 Chemical composition, chemical structure, metal absorption을 갖는 것을 FT-IR, SEM, XPS을 이용 하여 확인 하였다. Dopamine source의 보존에 대하여 명확하게 확인하기 위하여 FT-IR을 측정 하였다. 전압에 따른 Benzene ring, hydroxyl group의 비율을 확인 하였다. 낮은 전압으로 coating 된 Polydopamine-like film 일수록 hydroxyl group peak($3400{\sim}3000cm^{-1}$)과 비교하여 Benzene ring peak($1600{\sim}1580cm^{-1}$ and $1510{\sim}500cm^{-1}$)이 흡수를 더 많이 하는 것을 확인 할 수 있다. 이것은 Benzene ring이 파괴되지 않고 보존되는 것을 보여준다. Dopamine에서 Benzene ring은 absorption main factor인 catechol에 있는 chemical structure이다. 즉 Benzene ring peak이 높을수록 Catechol이 잘 보존 되었다는 의미 이다. Catechol의 보존은 absorption main factor가 보존 된다는 의미 이다. 이러한 Polydopamine-like film으로 As, Cr, Mg, Cu 200ppm solution에 대한 filtration 능력을 확인 하였다. As, Cr, Cu, Mg 의 제거율이 각각 약25%, 35%, 45%, 65%인 것을 확인 하였다. 이 수치는 시중에 판매되는 제품들과 비교했을 때 300%~500% 향상된 수치 이다.

• 한국가시화정보학회:학술대회논문집
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• 2005.04a
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• pp.87-112
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• 2005

분무를 정량적으로 측정하는 것은 노즐의 설계와 개발을 위해서 뿐만 아니라 연소 시스템 전반의 효율 및 불안정성의 제거, 공해 저감 등의 요구 조건을 만족하기 위해서 중요하다. 이를 위해 이전에는 분무장 내에 수집관을 삽입하는 기계적 패터네이터(Mechanical Patternator)와 같은 삽입식 측정 방식을 이용하여 왔으나, 최근에는 고속카메라, Malvern particle analyzer, PDPA, 광학 패터네이터(Optical Patternator)와 같은 분무장을 교란시키지 않으면서도 빠른 측정이 가능한 가시화 기술들이 적용되고 있다. 특히 광학 패터네이터는 레이저 평면광을 이용하여 분무를 측정하는 비삽입식 기술로 단시간 내에 분무장 내 액체 연료의 질량 및 액적 크기의 단면 분포를 동시에 얻어낼 수 있는 장점을 갖고 있다. 그러나 분무 액적들의 수밀도가 증가하는 경우에는 이들 액적에 의한 입사광 및 신호 감쇠, 다중산란 등에 의한 오차가 심하게 발생하여, 기존의 PDPA, PLIF 등의 광학 기법으로는 충분히 신뢰할 만한 결과를 얻기가 어렵게 된다. 이러한 분무를 정량적으로 측정하기 위해서는 입사광의 감쇠뿐만 아니라 분무장 내 액적들에 의한 신호의 감쇠 과정에 대한 고려가 필요하다. 주면 액적들의 영향을 최소한으로 줄이기 위해서는 레이저 평면광을 사용하는 광학 패터네이터와 달리 레이저 광선을 분무장에 조사하여 고압에서 나타날 수 있는 다중 산란에 의한 오차를 최소화할 수 있다. 이러한 이미지 처리 기법을 이용하는 광학 선형 패터네이터(Optical Line Patternator)를 이용하여 기존 레이저 계측기법으로 측정이 곤란하였던 고압 환경 하에서의 스월 동축형 인젝터의 분무 특성을 해석할 수가 있다. 2015(년도) 6,388, 2025(년도) 13,367, 2035(년도) 18,756, 2045(년도) 22,595, 시장점유율 증가로 인한 수출액 증가분 누적(억원) : 2015(년도) 3,411, 2025(년도) 8,847, 2035(년도) 14,433, 2045(년도) 18,005 또한 시나리오 비교평가를 실시하여 본 결과, 본 연구에서 정의한 순편익 누적(Cumulative Net Profit) 변수를 적용하면 현재 연구비 추세 대비 $30\%$ 까지 연구비를 증가 시키는 것이 효율적임을 알 수 있었다.성, 생산 용이성, 제품 디자인의 우수한 정도가 a=0.01 수준 하에서 유의적으로 추정되었다. 이들 변수들 중에서 품질경쟁력에 가장 큰 영향을 미치는 측정변수는 제품의 기본 성능, 수명(내구성), 신뢰성, 제품 디자인의 순서로 추정되었다. 이것은 한국 제조업이 아직 산업 디자인이 품질경쟁력에 크게 영향을 미치는 성숙단계에 이르지 못하였음을 의미한다. (2) 제품 디자인에게 영향을 끼치는 유의적인 변수는 연구개발력, 연구개발투자 수준, 혁신활동 수준(5S, TPM, 6Sigma 운동, QC 등)이며, 제품 디자인은 우선 품질경쟁력을 높여 간접적으로 고객만족과 고객 충성을 유발하는 것으로 추정되었다. 상기의 분석결과로부터, 본 연구는 다음과 같은 정책적 함의를 도출하였다. 첫째, 신상품 개발과 혁신을 위한 포괄적인 연구개발 프로젝트를 품질 경쟁력의 주요 결정요인(제품의 기본성능, 신뢰성, 수명(내구성) 및 제품 디자인)과 연계하여 추진해야 할 것이다. 둘째, 기업은 디자인 경영 마인드 제고와 디자인 전문인력 양성을, 대학은 디자인 현장 업무를 통하여 창의력 증진과 기획 및 마케팅 능력 교육을, 정부는 디자

• Solar Energy
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• v.15 no.3
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• pp.3-14
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• 1995

The Direct Contact heat Exchanger(DCHX) has been widely studied in the chemical industry for many years due to its inherent simplicity as a counter-current divice for heat and mass transfer. In many solar systems, the DCHX unit can be combined with the thermal storage unit, or alternatively, it can be used separately from the storage unit, much like an external(to storage) closed heat exchanger system. In the present work, the spray column type of direct contact heat exchangers are studied extensively to harness the solar energy for hot water and spaced heating. Some of the major considerations that are involved in the design of heat exchangers in this study are that : working fluid is a hydrocaabon(such as Texaterm) or water which is either lighter or heavier than storage medium. The experimental data have revealed some interesting characteristics concerning the application of DCHXs for solar energy utilization. These experiments are carried out in the line of solar heating system, major results are as follows : 1) the flow and aspect of working fluid drop for maxium heat transfer 2) efficiency and volumetric heat transfer coefficient of D.C.H.X with a heavier working fluid are higher than those of D.C.H.X with a lighter working fluid.

• The Journal of the Acoustical Society of Korea
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• v.16 no.2
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• pp.89-94
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• 1997

A new type SO$_2$ gas sensor with a particular inorganic thin film on SAW devices was developed. The sensor consisted of twin SAW oscillators of the center frequency of 54 MHz fabricated on the LiTaO$_3$ piezoelectric single crystal. One delay line of the sensor was coated with a CdS thin film that selectively adsorbed and desorbed SO$_2$, while the other was uncoated for use as a stable reference. Deposition of the CdS thin film was carried out by the spray pyrolysis method using an ultrasonic nozzle. The sensor could measure the concentration in air less than 0.25 parts per million of SO$_2$. Stability of the sensor turned out to be as good as less than 20ppm, recovery time after each measurement was as short as 5 minutes. Repeatability of the measurement was confirmed through so many reiterated experiments. Hence, the SAW sensor developed through this work showed promising performance as a microsensing tool of SO$_2$. Further work required to improve the performance of the sensor includes enhancement of the reactivity of the CdS thin film with SO$_2$ through appropriate dopant addition, an increase of the center frequency of the SAW device.

• The Korean Journal of Pesticide Science
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• v.15 no.1
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• pp.8-14
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• 2011

Methoxyfenozide and novaluron was sprayed on Aster scaber during cultivation period. Samples were collected 7 times in 0-10 days after spraying. Both methoxyfenozide and novaluron were extracted with methanol, partitioned with dichloromethane and analyzed by HPLC. At the fortified level of 0.4 and $2\;mg{\cdot}kg^{-1}$, average recovery of methoxyfenozide were $102.5{\pm}3.03$ and $84.4{\pm}2.82%$, and novaluron were $88.7{\pm}2.32$ and $90.6{\pm}4.50%$, respectively. Biological half-life of methoxyfenozide was 3.99 days and novaluron which was 3.16 days at recommended spray level on cultivation period of the plant. The major reducing factor of novaluron was the increased weight of the plant. In case of application of methoxyfenozide and novaluron following pesticide guide line for safe use, the final residue level was calculated to lower than maximum residue level (MRL).