• Archives of Plastic Surgery
• /
• 제35권2호
• /
• pp.208-213
• /
• 2008

Purpose: Distally based superficial sural artery island flap has some disadvantages such as postoperative flap edema, congestion, and partial necrosis of the flap margin. Venous congestion is an area of considerable concern in distally based superficial sural artery fasciocutaneous flap and is one of the main reasons for failure, particularly when a large flap is needed. However, we could decrease these disadvantages by means of venous superdrainage. Methods: From June of 2006 to June of 2007, a total of two patients with soft tissue defects of lower one third of the leg underwent venous supercharging distally based superficial sural artery island flap transfer. The distal pivot point of this flap was designed at septocutaneous perforator from the peroneal artery of the posterolateral septum, which was 5 cm above the tip of the lateral malleolus. Briefly, this technique is performed by anastomosing the proximal end of the lesser saphenous vein and collateral vein to any vein in the area of the recipient defect site. Results: No venous congestion was noted in any of the two cases. No other recipient or donor-site complications were observed, except for minor wound dehiscence in one case. In 3 to 6 months follow-up, patients had minor complaints about lack of sensation in the lateral dorsal foot. Conclusion: The peroneal artery perforator is predictable and reliable for the design of a distally based superficial sural artery island flap. Elevation of the venous supercharging flap is safe, easy, and less time consuming. In conclusion, the venous supercharging distally based superficial sural artery island flap offers an alterative to free tissue transfer for reconstruction of the lower extremity.

• 수산해양기술연구
• /
• 제49권1호
• /
• pp.51-57
• /
• 2013

A demand for bio-diesel oil increases as one of solution for exhaustion of fossil fuel and reduction of $CO_2$ emission, and research on bio-diesel is being carried out. Bio-diesel oil is mainly esterified from vegetable oil with methanol in order to use for fuel on diesel engine and has demerit that costs are increased as compared with directly using like non-esterified one. Bio-diesel oil within 3% mixed with gas oil is used at present, proportion of bio-diesel oil will be increase by 5% in future. We judged that wasted soybean oil non-esterified could be used on diesel engine with an electronic fuel injection according to previous researches with a mechanical fuel injection. A performance test using only gas oil, gas oil with esterified bio-diesel oil 5% and wasted soybean oil non-esterified 5% on diesel engine with the electronic fuel injection were carried out. It is noticed that gas oil with wasted soybean oil non-esterified 5% has more similar characteristics to gas oil than gas oil with esterified bio-diesel oil 5%.

• Archives of Plastic Surgery
• /
• 제36권2호
• /
• pp.153-160
• /
• 2009

Purpose: The heterodigital or homodigital artery island flap is a popular method of reconstruction for finger defects. Sometimes, digital artery island flap has some disadvantages such as postoperative flap edema, congestion, and partial necrosis of the flap margin. However, we could decrease these disadvantages by means of venous superdrainage. The aim of this study is to report usefulness and postoperative results of venous supercharging digital artery island flaps for finger reconstruction. Methods: From March of 2005 to March of 2008, a total of eight patients with soft tissue defects of the finger underwent venous supercharging digital island flap transfer. Briefly, the flap is harvested along with dorsal vein that is then anastomosed to a recipient vein in an end - to - end fashion, after flap transfer and insetting. Using this technique, eight patients were operated on, ranging in age 23 to 52 years. Results: All the flaps survived with a success rate of 100 percent, thus fully satisfying the reconstructive requirements. No postoperative flap congestion was recognized, obviating the need to take any measures for venous engorgement, such as suture removal. Among 8 cases, it was possible to make an long - term and follow - up observation more than 6 months. In these cases, the fact that light touches and temperature sensations can be detected in all the flaps. Cold intolerance and hyperesthesia were not seen in our series. Conclusion: Providing good harmony with conventional methods and microsurgery, inclusion of a vein with the heterodigital and homodigital artery island flap allows a more reliable and safer reconstructive choice for finger defects. The venous supercharged island flap is a reliable flap with a consistent arterial structure, and with its augmented venous drainage, it is more reliable, providing single - stage reconstruction of adjacent finger defects, including the fingertip.

• 한국자동차공학회논문집
• /
• 제24권6호
• /
• pp.619-626
• /
• 2016

The new 1.4 L turbocharged LPG direct injection (T-LPDI) engine is presented in this paper to improve the fuel efficiency of the vehicles installed with the 2.0 L LPG port fuel injection (LPI) engine, while maintaining the performance as a downsizing concept for the new engine platform development. Firstly, the return type high pressure LPG fuel supply system is designed and mounted in the new 1.4 L T-LPDI engine. As a result, this new engine shows a much better WOT performance and approximately 8 % of improved fuel economy level, as compared to the 2.0 L LPI vehicle. Secondly, the LPDI engine specific optimized design for high pressure fuel components and fuel injection control strategies are proposed and evaluated in order to overcome the restartability problem in a heat-soaked condition called the vapor lock phenomenon. Consequently, these experimental results illustrate a great potential for the developed 1.4 L T-LPDI engine as a possible substitute for the 2.0 L LPI engine.

• 대한기계학회논문집
• /
• 제16권5호
• /
• pp.965-973
• /
• 1992

본 연구에서는 산업용 가스전소자연순환보일러를 모델로 선정하여 이 모델에 영향을 주는 인자에 대하여 동적 해석을 하였다. 수위와 압력을 연결한 자연순환 보일러의 제어를 위한 총괄적인 블록 선도를 제시하였고, 이 선도를 토대로 전산프로 그램을 개발하고 계산치와 실제 측정치를 비교, 검토하여 이론 해석상의 모순이 없음 을 확증하였다. 연구결과를 산업용 자연순환 gas 보일러의 설계에 응용하도록 하여 보일러의 동특성을 제시하고 이것에 의한 전제어시스템의 신속하고 정확한 설계치를 제시하여 응용사용토록 하여 무엇보다도 전보일러시스템의 안전운전과 경제성(제작비 및 가동비)을 제고하는데 있다. 본 논문을 제1부, 제2부로 나누어 발표해야 하므로 제1부는 결론을 포함시키지 못하며 제2부에서 결론을 제시하겠으니 참조하여 주시기 바랍니다.

• 한국산학기술학회논문지
• /
• 제19권12호
• /
• pp.41-46
• /
• 2018

본 연구에서는 바이오가스 기반 예혼합 압축착화(Homogeneous charged compression ignition, HCCI) 엔진에 수소를 첨가하였을 때, 연소실 내부 압력, 온도 배출가스에 미치는 영향에 대해 살펴보았다. 자세히는 수소 첨가량과 과다공기량(${\lambda}$) 변화에 따른 연소실 압력 온도, 그리고 생성물로서의 NO, $CO_2$ 배출 특성을 화학 반응 해석 프로그램을 사용하여 고찰하였다. 대상의 엔진은 2300cc 바이오가스 엔진 발전기로서 압축비 13:1, 발전량 15kW 급이다. 과급압은 1.2bar 고정 조건이며, rpm은 1800rpm의 정속 조건이다. 엔진 연소 방식은 예혼합 압축 착화를 모사하였다. 본 연구를 진행하기에 앞서 바이오가스의 주요 조성인 메탄의 연소 및 산화 메커니즘에 대한 선행 연구에 대한 고찰을 통하여 연소반응 메커니즘을 규명하기 위한 반응 메커니즘 연구 기술의 경향을 살펴보고, 본 연구에 적용 가능한 반응 메커니즘을 선정하여 해석을 진행하였다. 수소를 첨가할 때 NO는 증가하는 반면, $CO_2$등의 배출량은 감소하였고 실린더 내부 압력이 상승하며, 상승 구간이 진각 됨을 알 수 있었다. 또한, 희박영역에서 수소 첨가가 가연 한계를 증가시켰다.

• 한국분무공학회지
• /
• 제25권4호
• /
• pp.162-169
• /
• 2020

The worldwide focus on reducing the emissions, fuel and lubricant consumption in T-GDI engines is leading engineers to consider the crankcase ventilation and oil mist separation system as an important means of control. In today's passenger cars, the oil mist separation systems mainly use the inertia effect (e.g. labyrinth, cyclone etc.). Therefore, this study has investigated high efficiency cylinder head-integrated oil-mist separator by using a compact multi-impactor type oil mist separator system to ensure adequate oil mist separation performance. For this purpose, engine dynamometer testing with oil particle efficiency measurement equipment and 3D two-phase flow simulation have been performed for various engine operating conditions. Tests with an actual engine on a dynamometer showed oil aerosol particle size distributions varied depending on operating conditions. For instance, high rpm and load increases bot only blow-by gases but the amount of small size oil droplets. Submicron-sized particles (less than 0.5 ㎛) were also observed. It is also found that the impactor type separator is able to separate nearly no droplets of diameter lower than 3 ㎛. CFD results showed that the complex aerodynamics processes that lead to strong impingement and break-up can strip out large droplets and generate more small size droplets.

• 한국가스학회지
• /
• 제24권6호
• /
• pp.1-10
• /
• 2020

반응성 조정 압축착화 (Reactivity Controlled Compression Ignition, RCCI) 연소는 착화원인 디젤 연료를 압축 행정 중 이른 시점에 미리 분사하여, 공기와 미리 섞여 들어온 천연가스 연료뿐만 아니라 디젤 연료 자체도 미리 연소 전에 공기와 혼합하여 착화를 이루는 전체 예혼합 혼소(Dual-fuel combustion) 방식의 일종이다. 따라서 기존의 혼소 방식 중에서도 RCCI 연소는 질소산화물(Nitrogen Oxides, NOx) 및 매연(Smoke)을 획기적으로 줄일 수 있고, 또한 높은 열효율을 유지할 수 있는 장점을 지니고 있다. 특히 연소 중 NOx의 발생은 연소 온도와 국부적인 당량비에 관계된 상황에서 당량비를 낮추기 위해 예혼합율을 높이는 시도뿐만 아니라, 연소 온도 감소를 위한 배기재순환(Exhuast Gas Recirculation, EGR)을 적용하는 것이 효과적이다. 그러나 배기재순환은 대개의 경우 터보차저의 압축기 전단에서 추출하는 HP-EGR(High Pressure-EGR) 방식을 적용하는 경우가 많으므로, EGR율을 높일 경우 터빈으로 공급되는 배기의 양이 줄어 배기 엔탈피 감소로 인해 과급이 줄어드는 악영향을 초래할 수 있다. 따라서 본 연구에서는 서로 다른 두 운전조건에서 천연가스-디젤 RCCI 연소를 시행할 때, EGR율 변화에 따른 엔진 시스템의 제동 출력 및 열효율의 변화에 대하여 실험적으로 분석하였다. 실험 조건은 1,200 rpm/29 kW 수준의 조건과 1,800 rpm/90 kW 이하 조건에서 수행하였으며 NOx와 smoke의 배출조건은 Tier-4 final 배기규제를 기준으로 삼았으며 엔진의 내구성을 고려하여 최고 연소압력은 160 bar를 넘지 않게 제어하였다. 그 결과 1,200 rpm/29 kW 조건에서는 EGR율을 4에서 30 %로 높이더라도 출력 및 열효율의 변화는 미미하였으나, 1,800 rpm 조건에서는 EGR율을 4에서 28 %로 증가할 경우 최대 과급 압력이 2.3에서 1.8 bar로, 최고 출력은 90에서 65 kW로, 열효율은 37에서 33 %로 감소함을 알 수 있었다. 따라서 효과적인 EGR공급을 위해서는 현재 압축기 전단에서 추출하는 EGR을 후단에서 추출하는 LP-EGR (Low Pressure EGR) 시스템이 효과적일 수 있음을 시사한다.

• Archives of Plastic Surgery
• /
• 제37권5호
• /
• pp.577-582
• /
• 2010

Purpose: When reconstruction for patients who have the large contralateral breast or a following large defect after mastectomy is required, conventional pedicled TRAM flap shows the unpredictable occurrence of fat necrosis and skin flap loss in a relatively high percentage due to insufficient blood supply. In an effort to obtain more stable TRAM flap blood circulation, we have performed a supercharged technique using deep inferior epigastric perforators (DIEP) with conventional pedicled TRAM flap. Methods: From September of 2006 to December of 2008, Fourteen supercharged TRAM flap were performed for breast reconstruction after modified radical mastectomy. The contralateral DIEP was anastomosed to the internal mammary vessels in contralateral pedicled TRAM flap or thoracodorsal vessels in ipsilateral pedicled TRAM flap. Nutrient vessels were selected by Multi-Detector Computed tomography (MD-CT) modalities. For the nutrient vessel, we used deep inferior epigastric vessels (DIEV) of the ipsilateral side in 8 patients, DIEV of the contralateral side in 6 patients. In addition, for the recipient vessel, we used thoracodorsal vessels in 8 patients, internal mammary vessels in 5 patients, intercostals artery perforators in 1 patient. Results: The mean age was 46.8 years and the average follow-up interval was 14 months. There were 11 immediate and 3 delayed breast reconstructions. Fat necrosis incidence rate in supercharged TRAM group was lower than in conventional TRAM flap group. There were no differences of the incidences of abdominal hernia in both groups. Conclusion: The supercharged TRAM flap produces an improvement in vascularity that permits use of all four zones of the flap. The breast reconstruction with supercharged technique is reliable and valuable methods which provide sufficient soft tissue from abdomen without significant complications.

• 대한기계학회논문집B
• /
• 제35권5호
• /
• pp.525-531
• /
• 2011

디젤엔진에서 배기가스 재순환(EGR; Exhaust Gas Recirculation)은 선택적 환원 촉매나 $NO_x$ 흡장 촉 매에 비해 $NO_x$ 배출 저감을 위한 가장 효과적인 기술이다. 점점 더 강화되어 가는 $NO_x$ 배출 규제를 만족시키기 위해서는 많은 양의 EGR 가스 공급이 필요하다. 저압 EGR은 일정한 과급 압력에서 가변형상 터보차져의 제어와 거의 독립적이기 때문에 EGR 공급 측면에서 보면 저압 EGR이 기존의 고압 EGR에 비해서 더 많은 장점을 갖는다. 본 연구에서는 저압 EGR이 연소 특성에 미치는 영향을 고압 EGR을 적용했을 때와 비교하였다. 각 EGR 루프에 대해 혼합기의 희석 정도에 따른 영향을 분석하기 위해 독립변수로써 희석비를 사용하였다. 저압 EGR을 적용하였을 때, 고압 EGR을 적용했을 때와 동등한 $NO_x$ 배출량을 유지하면서 연료 소비율과 매연 배출은 고압 EGR의 경우보다 좀 더 낮은 결과를 보였다.