Combustion properties of gaseous CH₄/O₂ coaxial jet flames in a single-element combustor

Kim, T.Y.,Choi, S.,Kim, H.K.,Jeung, I.S.,Koo, J.,Kwon, O.C. Butterworths [etc.] ; Elsevier Science Ltd 2016 Fuel Vol.184 No.-

Fundamental combustion properties of gaseous methane (CH<SUB>4</SUB>)/oxygen (O<SUB>2</SUB>) coaxial jet flames in a single-element combustor are experimentally evaluated as a preliminary step for subsequent studies of injection at very low temperature or using liquid O<SUB>2</SUB> for CH<SUB>4</SUB>/O<SUB>2</SUB> bipropellants, recently appearing to be the oncoming liquid bipropellant. A combustion chamber with quartz windows, a single shear coaxial injector and an exhaust nozzle on the downstream of the chamber is considered for the present study. Focusing on the measurements of the ignition and combustion stability limits of the coaxial jet flames in the chamber, flame visualization is also conducted by OH<SUP>*</SUP> chemiluminescence, schlieren imaging and direct imaging. Results show the ignition limits restricted than the combustion stability limits. Flame behaviors are largely classified into two, the stably attached flame and the oscillating, liftoff (near-blowout) flame. Due to cooling effects on the wall of the chamber, stably liftoff flame is not observed. The stability of the flame is greatest at fuel-rich condition (based on the injected amounts of CH<SUB>4</SUB> and O<SUB>2</SUB>). From the flame visualization flame thickness is found to be smaller than the injector lip thickness and insensitive to injection conditions. The laminar-flow behavior near the injector exit due to the strong burning of pure O<SUB>2</SUB> is observed even for high Reynolds numbers (Re). The flame visualization also exhibits the recirculating O<SUB>2</SUB> that enhances burning in the combustor through the reaction with the outer fuel jet. The results of ignition limits, combustion stability limits and flame visualization can be used as a database for researches of modeling the gaseous CH<SUB>4</SUB>/O<SUB>2</SUB> jet flames in the combustion chamber.

Trichloroethylene 취급 작업장의 공기 중 농도와 근로자의 요중 Trichloroacetic Acid 농도의 상관관계에 관한 조사연구

권오윤,이종태,문덕환,배기택 인제대학교 1990 仁濟醫學 Vol.11 No.3

부산ㆍ경남지역의 Trichloroethylene 취급 사업장 중 4개업종 20개소를 대상으로 기중 Trichloroethylene 농도를 측정하고, 이들 사업장 근로자 중 101명을 대상으로 요중 Trichloroaceticacid 농도를 분석하여 Trichloroethlene 폭로 정도를 평가하였다. Trichloroethylene, which is a chlorinated unsaturated hydrocarbon, is widely used as a solvent in degreasing operations. In the present study, the time-weighted average intensity of trichloroethylene exposure at work environments in 20 manufactures of 4 industries was assessed, at the same time trichloroacetic acid excretion in urine among 101 workers exposed to trichloroethylene was measured, and the exposure-excretion relationship was investigated. The results were summarized as follows; 1.The environmental trichloroethylene level was highest in metal machine industry(121.3ppm), followed by fabricated metal industry (106.0ppm), precision machine industry(65.0 ppm) and electrical machine industry(48.0 ppm). 2.The rate of urinary trichloroacetic acid concentration over 75mg/l among 101 workers was 42.6%(43 workers). 3.There is a linear correlation between the environmental exposure and urinary excretion(Y=1.05584X+35.65591, r=0.52401, p=0.0000).

Synthesis of titanium dioxide in O₂/Ar/SO₂/TiCl₄ microwave torch plasma and its band gap narrowing

Hong, Y.C.,Lho, T.,Lee, B.J.,Uhm, H.S.,Kwon, O.P.,Lee, S.H. Elsevier 2011 Current Applied Physics Vol.11 No.3

Titanium dioxide (TiO<SUB>2</SUB>) nanoparticles were synthesized directly by injecting gas-phase titanium tetrachloride (TiCl<SUB>4</SUB>) bubbled with a mixture of Ar and SO<SUB>2</SUB> into a 2.45 GHz microwave torch plasma operated in O<SUB>2</SUB> gas at atmospheric pressure. The absorption edge of the as-produced TiO<SUB>2</SUB> powders in the UV-Visible spectrum shifted from 457 nm to 483 nm as the SO<SUB>2</SUB> gas content in the mixture gas carrying the TiCl<SUB>4</SUB> was increased. According to X-ray photoelectron spectroscopy (XPS) and UV-Visible spectroscopy, the band gap narrowing was due to the incorporation of sulphur (S) species from the Ar and SO<SUB>2</SUB> mixture in the oxygen microwave torch plasma into the O site of TiO<SUB>2</SUB>2.

장기 저장연료의 열안정성 및 연료접촉 고무오링의 수명예측 연구

정근우(K. W. Chung),홍진숙(J. S. Hong),김영운(Y. W. Kim),한정식(J. S. Han),정병훈(B. H. Jeong),권태수(T. S. Kwon),서동욱(D. O. Suh),성민준(M. J. Sung),권영일(Y. I. Kwon) 한국트라이볼로지학회 2018 한국윤활학회지(윤활학회지) Vol.34 No.5

Thermal deterioration of fuel due to long-term storage influences engine performance and causes malfunctions. Fuel stability is usually evaluated via heat resistance and thermal stability during a brief heat shock at high temperature; storage stability in this scenario means that there is very little change in the quality of the fuel during long-term storage. In addition, rubber-based products such as oil seals, O-rings, and rubber hoses can influence the quality of the fuel. When these rubber products are in contact with fuel, they can swell, mechanically weaken, and occasionally crack, thus leaking low molar weight rubber and additives including plasticizer and antioxidant into the fuel to degrade its properties and shorten its useful lifetime. This study determines the thermal stabilities of three kinds of synthetic fuels by evaluating their low temperature kinematic viscosities, chemical composition changes via GC analyses, gross heat of combustion, and color changes. We evaluate the compression set of O-rings by immersing one NBR and two FKM rubber O-rings in the three synthetic fuel samples in airtight containers at variable storage temperatures for six months; from this, we estimate the lifetimes of the O-rings using the Power law model. There were very little changes in the chemical compositions and gross heat of combustion after six months of the experiment. The lifetimes are thus dependent on the materials of the rubber products, and in particular, the FKM O-ring was calculated to have a theoretical lifetime of 200 to 5,700 years. These results indicate that the synthetic fuels maintain their physical properties even after long-term storage at high temperatures, and the FKM O-ring is suitable for long-term sealing of these fuels.

Seroprevalence of equine piroplasms in the Republic of Korea

Seo, M.G.,Yun, S.H.,Choi, S.K.,Cho, G.J.,Park, Y.S.,Kwon, O.D.,Cho, K.H.,Kim, T.H.,Jeong, K.S.,Park, S.J.,Kwon, Y.S.,Kwak, D. Elsevier Scientific Pub. Co 2011 Veterinary parasitology Vol.179 No.1

Equine piroplasms include two tick-borne protozoan parasites, Babesia caballi and Theileria equi. Although no clinical equine piroplasmosis has been reported in the Republic of Korea, the possible existence of the disease has been proposed due to a nationwide distribution of the vector ticks. To determine if the antibodies against B. caballi and T. equi were present, 184 sera of horses (Equus caballus) raised in the Republic of Korea from 2007 to 2010 were assessed using cELISA kits. Two (1.1%) out of 184 sera were positive for T. equi, but none were seropositive for B. caballi. Both samples tested positive came from one region (Gyeonggi province). The accuracy of the cELISA was confirmed by PCR using primers specific to the 18S rRNA of T. equi. This study presents for the first time horses infected by T. equi in the Republic of Korea. Since the infection of T. equi occurred in horses raised in the Republic of Korea, further studies with continuous monitoring of the vector ticks for equine piroplasms and appropriate control programs need to be established.

Ti-6Al-7Nb 합금의 표면 활성에 미치는 양극산화 공정조건의 영향

권오성,류경호,박광범,이민호,배태성,이오연 대한금속재료학회 2005 대한금속·재료학회지 Vol.43 No.2

This study was performed to investigate whether the bioactivity of the anodized and hydrothermally treated Ti-6A1-7Nb alloy were affected by the process conditions of anodic oxidation. Anodizing was performed at a current density of 5-50 mA/㎠ in up to 240~300 V in electrolyte solutions containing DL-α-glycerophosphate(DL-α-GP) and calcium acetate (CA). Hydrothermal treatment was done at 300℃ for 2 hours to produce hydroxyapatite (HA) for bioactivity. Bioactivity was evaluated from surface activation layer formed on the surfaces in a Hanks' solution with pH 7.4 at 36.5℃ for 30 days. The size of micropores and the thickness of oxide film were increased by increasing the spark forming voltage, and more complex oxide layers were formed. HA crystals were observed on the anodic oxide film after hydrothermal treatment at 300℃ for 2 hours. The anodic oxide films were composed of strong anatase peak and rutile peak, and showed the increase in intensity of anatase peak after hydrothermal treatment. When electrolyte composition, voltage and current density were increased, the deposited HA crystals showed a fine shapes. Bioactivity in Hanks' solution was accelerated when the oxide films were composed of strong anatase peak with rutile peak. Oxide layers selectively showed surface activity at the pertinent electrolyte composition. When voltage and current density were increased, the surface activity was increased. The amount of Ca and P was increased in surface having bioactivity in Hanks' solution. (Received December 1, 2004)

식이 콜레스테롤에 대한 인지도 및 섭취현황 조사

권혁희,이달수,권오란,이혜영,박계각,송주완,김욱희 국립보건연구원 1994 국립보건원보 Vol.31 No.2

전이성 뇌종양의 임상양상 및 영상진단 소견

권오영,임병훈,이영배,이규용,김희태,김승현,김주한,김명호 대한신경과학회 1996 대한신경과학회지 Vol.14 No.4

小兒 慢性 骨髓性白血病 1例

權澤孚,宋貞玉,申東春,林正均 최신의학사 1976 最新醫學 Vol.19 No.4

Chronic myelocytic leukemia is one of rare type of leukemia in childhood. Frequent presenting initial symptoms are intermittent fever with unknown origin, abdominal distention, .hepatosplenomegaly, bleeding tendency, recurrent infection and generalized lymphadenopathy. The case was ten years old male child who was admitted with symptoms of abdominal distention, fever, and hepatosplenomegaly. He was confirmed by bone marrow aspiration and hematologic studies. We reviewed the literature about the etiology incidence, clinical symptoms, physical findings, hematologic findings, prognosis and management of chronic myelocytic leukemia briefly.

자돈 및 육성돈에 있어 α-1,6-galactosidase와 β-1,4-mannanase의 사료내 첨가가 성장 및 영양소 소화율에 미치는 영향

권오석,김인호,이상환,홍종욱,김지훈,문태현,이지훈 한국동물자원과학회 2003 한국축산학회지 Vol.45 No.2

본 연구는 양돈사료내 대두박 항영양인자인 α-galactosides와 galatomannan의 분해를 유도하는 α-1,6-galactosidase와 β-1,4-mannanase의 사료 내 첨가가 자돈 및 육성돈의 성장과 영양소 소화율에 미치는 영향을 조사하기 위하여 실시하였다. 시험 1은 개시시 체중 10.57±0.30㎏의 3원 교잡종 자돈 60두를 공시하였으며, 시험설계는 옥수수-건조유청-대두박 위주의 사료에 NRC (1998)의 영양소 요구량에 따라 처리한 대조구 (CON), 대조구 사료내 복합효소제를 0.1% 첨가한 처리구로 하였다. 사양시험기간동안, 일당증체량에 있어서는 대조구와 비교하여 EC0.1 처리구가 높은 것으로 평가되었으나 유의적인 차이는 보이지 않았다. 그러나 사료효율에 있어서는 대조구와 비교하여 EC0.1 처리구가 유의적으로 높게 평가되었다 (P<0.05). 건물과 질소 소화율에 있어서 대조구와 비교하여 처리구가 향상된 것으로 조사되었다 (P<0.05). 시험 2는 개시시 체중 22.30±0.45㎏의 3원 교잡종 육성돈 36두를 공시하였으며, 시험설계는 옥수수-대두박 위주의 사료에 NC (1998)의 영양소 요구량에 따라 처리한 대조구 (AME, adequate ME diet), 대조구 사료내 복합효소제를 0.1% 첨가한 처리구 (AME+EC0.1, Adequate ME diet + 0.1% 복합효소제), 대조구 사료에서 대사에너지 함량을 4% 낮춘 사료에 복합효소제를 0.1% 첨가한 처리구 (LME+EC0.1, Low ME diet + 0.1% 복합효소제)로 하였다. 총 30일간의 사양시험 기간동안, 일당증체량에 있어서는 AME 처리구와 비교하여 복합효소제 처리구가 유의적인 성장율이 높은 것으로 조사되었다 (P<0.05). 건물 및 질소 소화율에 있어서는 AME 처리구와 비교하여 복합효소제 첨가구가 유의적으로 높게 평가되었다 (P<0.05). 결론적으로, 자돈 및 육성돈 사료에 복합효소제의 첨가는 성장능력 및 영양소 소화율을 향상시키는 것으로 사료된다. For the Exp. I, a total of sixty pigs (10.57±0.30㎏ average initial body weight) were used in a 15-d growth assay to determine the effect of dietary α-1,6-galactosidase and β-1,4-mannanase on growth performance and nutrient digestibility. Dietary treatments included 1) CON (corn-dried whey-SBM based diet), 2) EC0.1 (CON diet + 0.1% enzyme complex of α-1,6-galactosidase and β-1,4-mannanase). Through the entire experimental period, gain/feed of pigs fed EC0.1 diet was higher (0.43 vs 0.52) than that of pigs fed CON diet (P<0.05). Pigs fed EC0.1 diet showed significant (P<0.05) improvement in dry matter (74.82% vs 82.41%) and nitrogen (70.59% vs 77.88%) digestibilities compared to pigs fed CON diet. For the Exp. 2, a total of thirty six pigs (22.30±0.45㎏ average initial body weight) were used in a 30-d growth assay to determine the effects of dietary α-1,6-galactosidase and β-1,4-mannanase in low energy diet on growth performance and nutrient digestibility. Dietary treatments included 1) AME (adequate ME diet), 2) AME+EC0.1 (AME diet + 0.1% enzyme complex) and LME+EC0.1 (low ME diet + 0.1% enzyme complex). Through the entire experimental period, average daily feed intake of pigs fed enzyme complex supplemented diets was higher than that of pigs fed CON diet (P<0.05). Also, pigs fed AME+EC0.1 diet showed significant (P<0.05) increase in ADFⅠ (1,401g vs 1,733g) compared to pigs fed CON diet. Pigs fed enzyme complex supplemented diet showed significant (P<0.05) improvement in dry matter and nitrogen digestibilities compared to pigs fed CON diet. In conclusion, the results obtained from these feeding trials suggest that the supplementation of α-1,6-galactosidase and β-1,4-mannanase was an effective means for improving growth performance and dry matter and nitrogen digestibilities in nursery and growing pigs.