• 대한화학회지
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• 제21권6호
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• pp.404-412
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• 1977

에탄올-물 혼합용매에서 납전극을 사용하여 니트로벤젠(${\phi}NO_2$)과 그 유도체의 전해 환원반응을 조사하였다. 산성용액에서는 퍼텐셜에 따라 ${\phi}NHOH\;및\;{\phi}NH_2$가 생성되었으며 니트로벤젠(${\phi}NO$)은 중간체가 아닌것으로 보였다. 염기성 용액에서는 ${\phi}NO$가 생성되며 더 낮은 퍼텐셜에서 환원시키면 ${\phi}N=N{\phi}$ 등 짝지어진 화합물이 생성됨을 확인하였다. 사용한 전해질 용액에서 ${\phi}NO\;와\;{\phi}NHOH$ 사이에 화학적인 짝지음 반응(coupling reaction)은 일어나지 않았다. 각각의 반응에 대해 전류-전압관계와 pH 의존도 및 반응물질에대한 반응 차수로부터 반응 메카니즘을 도출하였다. ${\phi}NO$가 생성되는 반응은 치환기가 있을 때도 같은 메카니즘을 따르는 것으로 보인다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제48권5호
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• pp.303-308
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• 2022

Objectives: Selection of treatment methods for mandibular condylar fractures remains controversial. In this study, we investigated treatment methods for condylar fractures to determine the indications for open or closed reduction. Patients and Methods: Patients >12 years of age treated for mandibular condylar fractures with a follow-up period of ≥3 months were included in this study. The medical records of enrolled patients were reviewed for sex, age, fracture site, treatment method (open or closed reconstruction), postoperative intermaxillary fixation period, operation time, and complications. Radiological analysis of fracture fragment displacement and changes in ramal height difference was performed using computed tomography and panoramic radiography. Results: A total of 198 patients was investigated, 48.0% (n=95) of whom underwent closed reduction and 52.0% (n=103) underwent open reduction. There was no significant correlation between reduction method and patient sex, age, or follow-up period. No statistically significant difference between the incidence of complications and treatment method was observed. None of the patients underwent open reduction of condylar head fracture. Binary logistic regression analysis showed that open reduction was significantly more frequent in patients with subcondylar fracture compared to in those with a fracture in the condylar head area. There was no statistically significant correlation between the groups and fracture fragment displacement. However, there was a significant difference between the treatment groups in amount of change in ramal height difference between the fractured and the non-fractured sides during treatment. Conclusion: No significant clinical differences were found between the open and closed reduction methods in patients with mandibular condylar fractures. According to fracture site, closed reduction was preferred for condyle head fractures. There was no significant relationship between fracture fragment displacement and treatment method.

• 치과방사선
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• 제28권1호
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• pp.205-213
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• 1998

This study was designed to reveal the correlationship between the internal derangement state of TMJ and clinical characteristics including pain and mandibular dysfunction. One hundred and twenty five subjects with TMJ signs and symptoms were chosen for two years. The level of pain and madibular dysfunction were evaluated by Visual Analog Scale(VAS) and Craniomandibular Index(CMI). The diagnostic categories of TMJ internal derangement were determined by arthrography and they included normal disc position, anterior disc displacement with reduction(ADDR), rotational disc displacement with reduction (RDDR), anterior disc displacement without reduction(ADDNR), and rotational disc displacement without reduction(RDDNR). Also disc perforation was used as a criteria to divide the diagnostic subgroups. The obtained results were as follows; 1. The patient distribution of each group was 5 in normal disc position(4％), 40 in ADDR(32％), 30 in RDDR(24％), 34 in ADDNR(27％), and 16 in RDDNR(13％). 2. Perforation was observed in 8％ of ADDR, 10％ of RDDR, 32％ of ADDNR, and 19％ of RDDNR. 3. CMI of non-reduction group was higher than that of reduction or normal group(p<0.05), but V AS showed no significant difference.4. CMI of perforation group was higher than that of non-perforation group in reduction group (p<0.05). 5. There were no significant differences of CMI and VAS between anterior disc displacement group and rotational disc displacement group in both reduction and non-reduction group. 6. CMI of RDDNR group was higher than that of RDDR group(p<0.05). 7. There were no significant difference of CMI and VAS between bilateral involvement group and unilateral involvement group(p<0.05).

• 한국세라믹학회지
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• 제43권4호
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• pp.224-229
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• 2006

Ag-Pd alloy nanoparticles were prepared by a chemical reduction method using hydrazine $(N_2H_4)$ as a reductant in $AgNO_3\;and\;Pd(NO_3)_2$ aqueous solutions. Characterization of these particles by X-ray powder diffraction revealed a bimetallic and crystalline silver-palladium alloy. The average size of the particles was influenced not by the reductant $(N_2H_4)$ concentration, but the concentration of the starting materials $(AgNO_3\;and\;Pd(NO_3)_2)$.

• 청정기술
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• 제8권3호
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• pp.111-117
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• 2002

동을 담지한 모더나이트를 이용하여 고정층 연속흐름 반응기에서 NO 분해와 CO에 의한 NO 환원을 실시하였다. NO 분해에서는 많은 동함량에서 $Cu^{\circ}/HM$이 CuO/HM보다 높은 분해 활성을 나타내었다. 이것은 $Cu^{\circ}/HM$과 CuO/HM에 존재하는 $Cu^{2+}$이온의 양과 CuO의 환원성 등의 차이에 관련된다고 보인다. NO 환원에서는 적은 동함량에서 Cuo/HM이 CuO/HM보다 높은 환원 활성을 나타내었다. 이것은 $Cu^{\circ}/HM$과 CuO/HM에 존재하는 CuO의 환원성과 입자 크기 등의 차이에 관련된다고 보인다.

• Journal of Mechanical Science and Technology
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• 제19권6호
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• pp.1358-1365
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• 2005

Flue gas recirculation (FGR) is widely adopted to control NO emission in combustion systems. Recirculated flue gas decreases flame temperature and reaction rate, resulting in the decrease in thermal NO production. Recently, it has been demonstrated that the recirculated flue gas in fuel stream, that is, the fuel induced recirculation (FIR), could enhance much improved reduction in NO per unit mass of recirculated gas, as compared to conventional FGR in air. In the present study, the effect of dilution methods in air and fuel sides on NO reduction has been investigated numerically by using $N_2$ and $CO_2$ as diluent gases to simulate flue gases. Counterflow diffusion flames were studied in conjunction with the laminar flamelet model of turbulent flames. Results showed that $CO_2$ dilution was more effective in NO reduction because of large temperature drop due to the larger specific heat of $CO_2$ compared to $N_2$. Fuel dilution was more effective in reducing NO emission than air dilution when the same recirculation ratio of dilution gas was used by the increase in the nozzle exit velocity, thereby the stretch rate, with dilution gas added to fuel side.

• 대한환경공학회지
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• 제38권5호
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• pp.269-278
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• 2016

수도권지역의 대기오염을 개선하기 위해 수도권 대기환경 개선에 관한 특별법이 제정되었고 2005년부터 시행되었다. 그 결과 수도권의 대기질은 개선되었으나 각 대책의 평가에 대한 연구는 부족하다. 이에, 본 연구는 도로이동오염원의 배출량 저감정책이 질소산화물의 농도저감에 미치는 영향을 정량적으로 분석하고자 하였다. 이를 위해 MM5-SMOKE-CMAQ 모델 시스템을 이용하여 수치모사를 수행하였다. 2007년 수도권 $NO_x$ 저감 배출량은 16,561톤으로서 4.7%의 저감률을 보였다. 여러 대책 중 제작차 배출허용기준강화 대책이 가장 효과적이었다. 지역별 삭감실적은 차이가 커서 서울의 삭감률은 인천과 경기의 약 2배에 달하였다. 결과적으로 $NO_x$ 저감의 효과는 서울 도심에 집중적으로 나타났다. 이동오염원 저감대책에 의하여 서울의 $NO_2$ 농도는 연평균 0.60 ppb (2.0%)저감되었고 인천과 경기는 각각 0.18 ppb (1.5%), 0.22 ppb (1.7%)가 저감되었다. 봄과 겨울의 저감농도는 여름과 가을에 비해 1.5~2.0배 정도 높았다. 도심과 풍하지역으로의 $NO_2$ 저감효과 분산때문에 도심지역의 $NO_x$ 배출량 저감이 직접적인 $NO_2$ 농도 저감에 효과적이지 않았다.

• 대한기계학회논문집B
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• 제34권3호
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• pp.283-290
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• 2010

이 연구의 목적은 NOx 저감을 위한 연료희박 재연소 기법과 산화제 다단 연소 기법의 혼합 기법의 실험적 연구를 목표로 한다. 실험용 연소로에서 재연소 연료 분율, 재연소 노즐 직경, 산소부하도 및 재연소 연료 분사 위치등을 고려한 실험을 수행 하였다. 또한, 산화제 다단 연소를 통하여 생성된 유동장이 NOx 저감에 미치는 영향을 연료희박 기법의 NOx 저감율과 비교하는 실험을 수행하였다. 실험을 통하여 연료희박 재연소와 산화제다단연소 기법의 혼합 기법이 NOx 저감에 미치는 긍정적인 효과를 관찰 하였다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.415-420
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• 2009

Selective Catalytic Reduction(SCR) has been used for the reduction of $NO_x$ in a steam supply boiler. Recently, the reduction of $NO_x$ becomes an important research field because of its negative effect on an environment. Shape optimization of circular poles installed in the chamber, which is located in upstream of a SCR, has been performed using response surface method and three-dimensional Navier-Stokes analysis to enhance gas flow uniformity. Three design parameters, diameter, arranging angle and stretching ratio of circular poles, are considered in the present study. Throughout the shape optimization of a circular pole, gas flow uniformity is successfully increased by decreasing local recirculation flow in a square duct chamber. Recirculation flow observed in the corner of the square duct can be reduced by proper installation of a guide vane or a blunt body. Detailed flow characteristics are also analyzed and discussed.

• 운동영양학회지
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• 제17권2호
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• pp.43-48
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• 2013

This study aims to investigate changes in plasma lipid concentrations and appetite-regulating hormone levels after a 4% body fat reduction using a 9-week intervention involving aerobic exercise, a fat-oxidizing agent, and diet limitation. After the 9-week intervention, the aerobic exercise plus hydroxycitric acid (EX+HCA), exercise (EX), and diet limitation (DIET) groups achieved the target 4% body fat reduction from the baseline value. None of the plasma lipid indicators showed significant intergroup differences, indicating that plasma lipid levels are not influenced by body weight regulation. With regard to appetite-regulating hormones, no significant intergroup differences were observed in glucose, insulin, or glucagon-like peptide-1 levels, unlike ghrelin and leptin. Ghrelin levels in particular tended to decrease in the DIET group and increase in the HCA+EX and EX groups. Leptin levels significantly decreased in the HCA+EX and EX groups, whereas no differences were observed in the DIET group. Such results indicate that exercise alone without the administration of obesity diet supplements induces elevation in ghrelin levels and reduction in leptin levels, but that diet restriction alone does not influence changes in leptin levels. Taken together, we could not confirm any synergic effects arising from the use of a fat-oxidizing agent during an exercise program to control body weight. Furthermore, diet limitation unsupported by exercise had no effect on muscle mass reduction or appetite-regulating hormone levels; thus, it is not recommended as an effective body weight control method.