• Clean Technology
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• v.13 no.2
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• pp.109-114
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• 2007

In this study, we performed basic researches to develop wet purification system for improving air qualities of ventilation in semiconductor manufacturing process. Using 0.5 M aqueous solution of $KMnO_4$, 50 ppm of $NH_3$, SOx and NOx were reduced to 99% successfully. However, the removal of $O_3$ was limited to $22{\sim}30%$ for all the tested chemical solutionsincluding $KMnO_4$. Therefore, adoption of a dry ozone filter is necessary to reduce $O_3$ below a satisfactory level. For all the chemical solutions tested, NOx removal efficiency increased as NOx was mixed with $O_3$. As chemical solution was sprayed using water spraying system equipped with air atomizing type nozzle, the removal efficiencies of gaseous pollutants increased due to the increase of gas-liquid interfacial area.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.151.2-151.2
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• 2012

터보펌프 구동에 사용된 가스발생기 생성가스를 연소기로 공급하여 주추력 발생에 사용하는 다단연소 사이클 로켓엔진은 고추력을 요하는 우주 발사체에 널리 사용되고 있다. 다단연소 사이클 로켓엔진에 사용되는 가스발생기를 예연소기라 부르며 케로신과 액체산소를 추진제로 하는 다단연소 사이클 로켓엔진에는 산화제 과잉 예연소기가 사용된다. 예연소기는 터보펌프 구동을 목적으로 하기 때문에 예연소기 생성가스의 횡단면 온도분포는 터빈에 의해 제한되는 온도범위 내에서 균일하여야 하며 넓은 운전영역에서 안정적인 연소가 이루어져야 한다. 산화제 과잉 예연소기는 모든 추진제가 혼합헤드를 통해 분사되는 방식과 추진제를 혼합헤드와 연소실로 나누어 공급하는 방식이 있다. 기술검증을 위해 산화제 일부와 연료를 혼합헤드를 통해 연소실에 공급하여 1차 연소시키고 나머지 산화제를 연소실 냉각채널을 거쳐 연소실 중앙의 분사공을 통해 연소실로 주입하여 기화시키는 형태로 최종적으로 연소압 20MPa, 혼합비 60에서 작동하는 산화제 과잉 예연소기를 설계하여 연소시험을 수행하였다. 혼합헤드에는 별도의 점화용 분사기 없이 전체 연료 분사기를 통해 점화용 연료인 TEA/TEB 혼합물을 분사하여 점화하였다. 추진제를 2단으로 공급할 수 있도록 고안된 가압식 연소시험 설비에서 10회, 누적 60초 이상의 연소시험이 성공적으로 수행되었다. 연소시험결과 넓은 작동영역에서 안정적 연소특성과 생성가스 온도 분포의 균일성을 확인할 수 있었다. 고온 고압의 산화제 과잉 예연소기 기술 확보를 통해 케로신/액체산소 다단연소 사이클 로켓엔진 개발을 위한 기술적 기반을 마련하였다.

• Polymer(Korea)
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• v.38 no.1
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• pp.98-102
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• 2014

Nowadays, silk fibroin receives a lot of attention as novel natural biomaterials due to its excellent biocompatibility and biodegradability. Electrohydrodynamic spraying (EHDS) is one of the method for the preparation of micro or nanoparticles by applying high voltage to the polymer solution. In this research, we fabricated silk fibroin porous microparticles by electrohydrodynamic spraying. Poly(ethylene glycol) (PEG) was added to the fibroin solution to give pores to silk fibroin microparticles. By the addition of PEG, the microparticle size was decreased despite of the decrease in conductivity and the increase of viscosity of the spraying solution. It seems that the immiscibility of silk fibroin and PEG affected much more to the microparticle size than the conductivity and viscosity. Immersing the as-sprayed microparticles into the water removed the phase-separated PEG, and finally, porous silk fibroin microparticles were prepared. The porous silk fibroin microparticles are expected to be applied as drug carriers in drug delivery or cell carriers in tissue engineering.

• Journal of the Korean Ceramic Society
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• v.38 no.6
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• pp.545-550
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• 2001

본 연구에서는 분사연소합성(SCS)을 위한 기초단계로서 용액연소합성에 대한 거동을 살펴보고자 알루미나 합성을 모델로 하였으며 이를 위해 전구체에 대한 열분해거동, 그리고 각 온도에서의 평형종 분압 계산 및 합성과정을 조사하였다. 각각의 열중량 분석(TGA) 결과 산화제와 환원제(연료)의 열분해 이력이 서로 다르게 나타났으며, 열역학 응용 프로그램인 ChemSag에 의한 평형종 분압의 계산에서 연소속도를 저하시킬 수 있는 $CO_2$와 수증기 가스 분압이 상당부분 존재하였다. 산화제/환원제 혼합물의 열분석(DTA/TG) 결과 산화제와 환원제의 열분해 거동의 차이, 그리고 매우 작은 시료의 양으로 인해 263$^{\circ}C$에서 발열피크가 매우 작게 나타났다. 열분석 시료에 비해 발열 에너지를 높이기 위해 산화제와 환원제 혼합 전구체를 비이커에서 증기압을 조절하며 가열시켜 본 결과 27$0^{\circ}C$에서 $\alpha$-Al$_2$O$_3$생성물을 얻을 수 있었다. 따라서 분사연소합성 반응을 통해 세라믹 원료를 합성하기 위해서는 연소과정 중 열분해 거동과 평형종의 분압을 고려하여야 한다.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.9-17
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• 2007

The performance test of recirculation line in propellant feeding system was carried out. Liquid oxygen was used as cryogenic propellant and helium was used as recirculation promotion gas. Tests were done in cases at atmospheric pressure and at pressure of 4 barg in the ullage space of propellant tank. Liquid oxygen recirculation flowrate with helium injection flowrate and temperature distribution along the line were measured. There was appropriate helium injection flowrate for gas-lift recirculation system. Test data were used to make calculation program by test data correlation method. In this paper the procedure of calculation was presented and the results were compared to test data.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.1
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• pp.37-44
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• 1993

Fuel injection system is an important tool in the exhaust emission and performance of a diesel engine. Effects of the fuel injection system in diesel combustion was investigated experimentally by measuring the performance and analyzing the combustion phenomena in a D.I. diesel engine. The selected injection parameters were nozzle opening pressure, nozzle projection length, and nozzle spray angle. From the measured results, it is shown that the fuel injection pipe diameter is an effective means to improve engine performance in a middle and high speed range and the 2 stage spring nozzle holder has the advantage of increasing the engine performance due to the initial injection pressure in a low speed range. It has been also shown that increasing nozzle opening pressure resulted in decrease in smoke, but increase in NO$_{x}$ from the engine.e.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.251-255
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• 2005

By using liquid film thickness measurement the spray characteristics of swirl injector according to the geometric parameters were investigated in this paper. A specially designed injector having a variable backhole length, swirl chamber length, orifice length was used to measure the liquid film thickness. The spray characteristics of the injector were represented by mass flow rate according to the injection pressure, liquid film thickness in the lower orifice, spray cone angle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.61-64
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• 2009

A study on the variation of combustion performance by oxidizer/fuel ratio was conducted. Shower head type injector was used. Injector propelled by liquid kerosene and liquid hydrogen peroxide. The designed operation condition for thrust and combustion pressure were 200N and 10bar. It is found that optimum oxidizer/fuel ratio.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.812-817
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• 2001

Impinging spray characteristics were investigated to find suitable injection pressure by using high pressure injection system. Spray radius and spray height were increased continuously until 2,500bar but the rate of enhancement was decreased suddenly over this injection pressure region. It is expected that the maximum suitable injection pressure of impinging spray exists at around 2,500bar.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.131-134
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• 2007

This numerical analysis was performed in order to validate adoption of the sheet breakup model in high-pressure environment, which were used for prediction of spray characteristics in atmosphere environment. In experiments the higher environment pressure the shorter breakup length; the results of new sheet breakup model predicted the breakup length in good agreement with experimental results qualitatively and quantitatively. Also the shape of spray calculated by numerical analysis were agreed well with experiments quantitatively.