Injection profile effects on low speed axial compressor stability enhancement

Lim, Hyung-Soo,Bae, Hyo-Jo,Lim, Young-Cheon,Song, Seung-Jin,Kang, Shin-Hyoung,Yang, Soo-Seok 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.6

This study presents stability enhancement of a four-stage low speed axial compressor with different injection profiles. The injection profiles include one-step injection, multi-step injection, and continuous injection. For the tip injection, eight Coanda-shaped nozzles have been installed at eight equally spaced circumferential locations upstream of the first stage rotor. Two external blowers injected air steadily through the Coanda-shaped nozzles. With tip injection, the compressor operation range has been extended. To analyze stall margin improvement, spatial Fourier transform (SFT) has been performed. The coefficient of SFT (SFC) is a complex number, containing information about the magnitude and the phase of SFC. By analyzing the distribution of the magnitude and the phase of SFC, the stall onset point has been verified. Furthermore, the injection flow rate has been changed during injection process to examine the possibility of attaining an additional flow extension. Increasing the injection rate during stabilization can bring about additional operation range extension. These results suggest a new injection method to reduce the total amount of the injection air.

유리체강내 주입술 후 유리체 역류를 일으키는 인자

지동현(Donghyun Jee),김보윤(Bo Youn Kim),나태윤(Tae Yoon Ra) 대한검안학회 2010 Annals of optometry and contact lens Vol.9 No.2

목적: 유리체강내 주입술 후 발생하는 유리체 역류에 관여하는 위험인자를 분석하여 유리체 역류를 최소화시키는 방법을 알아보고자 하였다. 대상과 방법: 본원에서 베바시주맙 유리체강내 주입술을 받은 122명 122안을 대상으로 연구를 시행하였다. 유리체 역류의 정도는 주입술 후 발생하는 결막 수포의 최대 지름으로 측정하였고, 술 전 안압, 수정체의 유무, 공막창의 형태, 주사 바늘 제거 속도를 조사하여 유리체 역류에 영향을 주는 인자를 분석하였다. 결과: 술 전 안압의 변화와 수정체 유무에 따라 유리체 역류는 통계적으로 유의한 변화를 보이지 않았다. 주사바늘주입 형태에 따라 결막 수포의 지름은 수직주입군에 비해 터널주입군에서 역류량을 유의하게 줄일 수 있었다(p=0.004). 주사바늘을 제거 속도에 따라 결막 수포의 지름은 바늘을 빠르게 제거한 군에 비하여 주사바늘을 천천히 제거할 때 유의하게 역류가 적게 발생함을 확인할 수 있었다(p<0.001). 결론: 유리체강 내 주입술 시 터널형태 공막창을 만들어 주입 후 천천히 주사바늘을 제거하는 것이 유리체 역류를 줄일 수 있는 좋은 방법으로 기대된다. Purpose: To analyze the factors affecting the vitreous reflux after intravitreal (IV) injection. Methods: A prospective study was conducted for 122 eyes of 122 patients who had undergone intravitreal Bevacizumab (AvastinⓇ) injection. The amount of vitreal reflux was measured as the conjunctival blebs size by using caliper after IV injection. We investigated the pre-injection IOP, status of lens, injection technique, and speed of needle removal as risk factors and analyzed the factors affecting the vitreous reflux after IV injection by multivariate linear regression test. Results: There was no statistically significant correlation between pre-injection IOP and mean conjunctival bleb size (CBS) (p=0.084). The relationship between mean conjunctival bleb size and lens status was not statistically significant, (1.95±1.84 mm) in phakic eyes and (2.18±1.66 mm) in pseudophakic eyes (p=0.723). The relationship between mean CBS and injection technique was statistically significant (p=0.004). The mean CBS was less with the tunneled scleral injection (1.87±1.80 mm) than in eyes undergoing the straight scleral injection (2.03±1.80 mm). Also the mean CBS was statistically less with the slow group of needle removal (1.54±1.58 mm) than in eyes undergoing the fast group of needle removal (3.36±1.70 mm) (p<0.001). Conclusions: Slow removal of needle and the tunneled scleral incision can be expected to decrease the vitreal reflux after intravitreal injection.

Single pretreatment of remifentanil may reduce pain after propofol and rocuronium injection in rapid sequence induction

최윤지,박한석,이한,윤승주 대한마취통증의학회 2012 Korean Journal of Anesthesiology Vol.63 No.5

Background: We designed this double-blind, placebo-controlled study to compare the efficacy of remifentanil in reducing the pain of both propofol and rocuronium injection during rapid-sequence induction. Methods: Ninety-five patients, scheduled for elective surgery under general anesthesia, were divided into 3 groups:saline (Group S, n = 31), remifentanil 1 μg/kg (Group R, n = 32), and lidocaine 1.5 mg/kg (Group L, n = 32) were administered after tourniquet application. The occlusion was released after 1 min and 5 ml of 1% propofol was injected over 10 s. Pain on propofol injection was evaluated by a 10-point verbal numeric rating scale (VNRS). The rest of the induction dose of propofol and 1 mg/kg of rocuronium, were injected. Pain on rocuronium injection was evaluated by a four-point score (FPS). Results: The VNRS of propofol injection was as follows: R (0.78) = L (1.34) < S (4.26). The incidence of withdrawal response due to rocuronium was as follows: R (6.3%) < L (53.1%) < S (83.9%). The FPS of rocuronium injection was as follows: R (0.81) < L (1.78) < S (2.93). Conclusions: Pretreatment with a bolus of remifentanil was effective in simultaneously reducing injection pain of propofol and rocuronium. In addition, remifentanil pretreatment was more effective in suppression of withdrawal response by rocuronium than lidocaine. Background: We designed this double-blind, placebo-controlled study to compare the efficacy of remifentanil in reducing the pain of both propofol and rocuronium injection during rapid-sequence induction. Methods: Ninety-five patients, scheduled for elective surgery under general anesthesia, were divided into 3 groups:saline (Group S, n = 31), remifentanil 1 μg/kg (Group R, n = 32), and lidocaine 1.5 mg/kg (Group L, n = 32) were administered after tourniquet application. The occlusion was released after 1 min and 5 ml of 1% propofol was injected over 10 s. Pain on propofol injection was evaluated by a 10-point verbal numeric rating scale (VNRS). The rest of the induction dose of propofol and 1 mg/kg of rocuronium, were injected. Pain on rocuronium injection was evaluated by a four-point score (FPS). Results: The VNRS of propofol injection was as follows: R (0.78) = L (1.34) < S (4.26). The incidence of withdrawal response due to rocuronium was as follows: R (6.3%) < L (53.1%) < S (83.9%). The FPS of rocuronium injection was as follows: R (0.81) < L (1.78) < S (2.93). Conclusions: Pretreatment with a bolus of remifentanil was effective in simultaneously reducing injection pain of propofol and rocuronium. In addition, remifentanil pretreatment was more effective in suppression of withdrawal response by rocuronium than lidocaine.

1D 시뮬레이션 기반 GDI 인젝터의 비선형적 분사 특성 해석에 대한 연구

이진우,문석수,허동한,강진석 한국분무공학회 2023 한국액체미립화학회지 Vol.28 No.4

Multi-injection scheme is being applied to GDI combustion to reduce PM and PN emission to meet the EU7 regulation. However, very short injection duration encounters the ballistic injection region, which injection quantity does not increase linearly with injection duration when applying multi-injection. In this study, numerical studies were conducted to reveal the cause of ballistic injection and the effect of design parameters on ballistic region using 1-D simulation, AMESim. Injection rate and injection quantity were compared with experiment to validate the established model, which showed the accuracy with 10% error. The model revealed that the tendency of ballistic region coincides with the needle motion behavior, which means that parameters at the upper part of needle such as electro-magnetic force, needle spring force and needle friction force have dominant effect on ballistic injection. To figure out the effect of electro-magnetic and needle friction force on ballistic, those parameters were varied to plus and minus 10% with model. The result showed that those parameters clearly changed the ballistic region characteristics, however, the impact became insignificant for outside of ballistic region, which means that the ballistic injection is mainly influenced by initial motion of injector needle.

승용 디젤 CRDI 엔진의 다단 분사 및 분사압력이 연소 및 배기 특성에 미치는 영향

노현구(Hyungu Roh),전학식(Haksik Jeon),이창식(Changsik Lee) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

This paper describes the effect of the multiple injection and injection pressure on the combustion and emission characteristics in a CRDI diesel engine at various operating conditions. In order to investigate the influence of multiple injections and injection pressure in a diesel engine, the fuel injection timing was varied double pilot injections and main injection at TDC. The experimental apparatus is consisted of DI diesel engine with 4 cylinders, EC dynamometer, multi-stage injection and injection pressure control system, and exhaust emissions analyzer. The combustion and emission characteristics are investigated of various injection strategies such as analyzed for the main, one pilot-main, double pilot-main strategy. The results showed that the average of peak combustion pressure is increased with the increase of injection pressure. Also, double pilot injection has a great effect on reducing NOx emissions because the decrease of peak heat release rates. However soot is increased at the double pilot injection compared to single injection. Based on this result, it showed that the combustion and emission characteristics can be improved as the pilot injection is retarded.

Factors Affecting the Effectiveness of Zinc Injection in Nuclear Power Plants

Yongsang Cho,Chorong Kim,Daseul Ham,Hyeokcheol Kwon,Jinsu Choi,Gyumin Song 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

Zinc injection into the coolant system of nuclear power plants is an effective method for reducing corrosion and improving performance. The effectiveness of this method is influenced by various factors such as zinc concentration and injection rate. This paper provides an overview of the factors affecting the effectiveness of zinc injection in nuclear power plants, with a focus on zinc concentration and injection rate, and discusses various research results on the effects of these factors on corrosion reduction and coolant system performance. Zinc concentration is an important factor affecting the effectiveness of zinc injection. The research results show that gradual increases in zinc concentration are more effective for coolant system stability. However, the concentration should not exceed the recommended levels as high zinc concentrations can have negative effects on the system. Injection rate is also an important factor affecting the effectiveness of this method. The research results show that gradual increases in injection rate are more effective for coolant system stability. However, excessive injection rates can have negative effects on the system such as overload of the zinc injection facility and chemical shocks within the coolant system, and therefore, should be optimized. In conclusion, zinc concentration and injection rate are important factors affecting the effectiveness of zinc injection in nuclear power plants. The optimal concentration and injection rate should be determined based on specific reactor conditions and system requirements, and efforts should be made to maximize corrosion reduction and performance improvement.

Intra-articular Injection of Chitosan-Based Supramolecular Hydrogel for Osteoarthritis Treatment

Mou Donggang,Yu Qunying,Zhang Jimei,Zhou Jianping,Li Xinmin,Zhuang Weiyi,Yang Xuming 한국조직공학과 재생의학회 2021 조직공학과 재생의학 Vol.18 No.1

Background: Pain and cartilage destruction caused by osteoarthritis (OA) is a major challenge in clinical treatment. Traditional intra-articular injection of hyaluronic acid (HA) can relieve the disease, but limited by the difficulty of long-term maintenance of efficacy. Methods: In this study, an injectable and self-healing hydrogel was synthesized by in situ crosslinking of N-carboxyethyl chitosan (N-chitosan), adipic acid dihydrazide (ADH), and hyaluronic acid–aldehyde (HA-ALD). Results: This supramolecular hydrogel sustains good biocompatibility for chondrocytes. Intra-articular injection of this novel hydrogel can significantly alleviate the local inflammation microenvironment in knee joints, through inhibiting the inflammatory cytokines (such as TNF-α, IL-1β, IL-6 and IL-17) in the synovial fluid and cartilage at 2- and even 12-weeks post-injection. Histological and behavioral test indicated that hydrogel injection protected cartilage destruction and relieved pain in OA rats, in comparison to HA injection. Conclusion: This kind of novel hydrogel, which is superior to the traditional HA injection, reveals a great potential for the treatment of OA. Background: Pain and cartilage destruction caused by osteoarthritis (OA) is a major challenge in clinical treatment. Traditional intra-articular injection of hyaluronic acid (HA) can relieve the disease, but limited by the difficulty of long-term maintenance of efficacy. Methods: In this study, an injectable and self-healing hydrogel was synthesized by in situ crosslinking of N-carboxyethyl chitosan (N-chitosan), adipic acid dihydrazide (ADH), and hyaluronic acid–aldehyde (HA-ALD). Results: This supramolecular hydrogel sustains good biocompatibility for chondrocytes. Intra-articular injection of this novel hydrogel can significantly alleviate the local inflammation microenvironment in knee joints, through inhibiting the inflammatory cytokines (such as TNF-α, IL-1β, IL-6 and IL-17) in the synovial fluid and cartilage at 2- and even 12-weeks post-injection. Histological and behavioral test indicated that hydrogel injection protected cartilage destruction and relieved pain in OA rats, in comparison to HA injection. Conclusion: This kind of novel hydrogel, which is superior to the traditional HA injection, reveals a great potential for the treatment of OA.

1형 미숙아망막병증의 치료로서 일차 유리체강내 라니비주맙 주입술의 효과

정규철(Gyu Chul Chung),문성혁(Sung-Hyuk Moon) 대한안과학회 2017 대한안과학회지 Vol.58 No.9

Purpose: To evaluate the effectiveness and safety of primary intravitreal ranibizumab injection as a treatment for retinopathy of prematurity. Methods: Retrospective analysis of the medical records of patients diagnosed with retinopathy of prematurity and treated with intravitreal ranibizumab injection from January 1, 2013 to January 1, 2016 was performed. We complied with the standards for ‘prethresold, type 1’ established by the Early Treatment of Retinopathy of Prematurity study for intravitreal ranibizumab injection. The follow-up period after injection was at least 9 months. Patients who received additional treatment such as laser photocoagulation or intravitreal injection without reactivation of retinopathy of prematurity were excluded. Results: A total of 21 patients (39 eyes) were included in this study. Nine (16 eyes) were male and 12 (23 eyes) were female. The average duration between treatment decision and intravitreal ranibizumab injection was 2.1 ± 1.5 days. Complete regression of the plus sign occurred 18.2 ± 9.1days after injection. One eye with reactivation was treated with panretinal laser photocoagulation while four other eyes with reactivation were treated with intravitreal bevacizumab injection. There were 87.1% (34/39) eyes that underwent primary intravitreal ranibizumab injection with stable results without any reactivation. There were no systemic complications related to intravitreal ranibizumab injection. Conclusions: Primary intravitreal ranibizumab injection as a treatment for retinopathy of prematurity showed good efficacy and safety. However, thorough evaluation is needed after primary intravitreal ranibizumab injection due to the potential for reactivation. Long-term monitoring is needed after intravitreal ranibizumab injection. J Korean Ophthalmol Soc 2017;58(9):1080-1086

Optimization of the injection-port geometries of a vapor injection scroll compressor based on SCOP under various climatic conditions

Kim, Dongwoo,Chung, Hyun Joon,Jeon, Yongseok,Jang, Dong Soo,Kim, Yongchan Elsevier 2017 ENERGY Vol.135 No.-

<P><B>Abstract</B></P> <P>An analytical study is conducted to optimize the injection-port geometries of a vapor injection asymmetric scroll compressor operating under various climatic conditions. A numerical model was developed to predict the performance of the vapor injection asymmetric scroll compressor in the heating mode according to various operating parameters, and this numerical model was validated using data measured in a vapor injection heat pump. The effects of the location and number of injection ports on the performance of the asymmetric scroll compressor were analyzed using the numerical model. Both the optimal injection-port angle and required injection-port area increased as the outdoor temperature decreased in order to increase the injection mass flow rate. The optimized injection port designs were then proposed for the asymmetric scroll compressor in order to achieve the maximum SCOP (seasonal coefficient of performance) under various climatic conditions, improving the SCOP by 2%–6% relative to the baseline injection compressor.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A numerical model is developed to predict the performance of a vapor injection scroll compressor. </LI> <LI> The effects of the injection-port geometries on the performance of the heat pump are analyzed. </LI> <LI> The SCOPs of the heat pump with various injection-port designs are compared. </LI> <LI> The optimized injection-port designs are suggested under various climatic conditions. </LI> </UL> </P>

Performance comparison between R410A and R32 multi-heat pumps with a sub-cooler vapor injection in the heating and cooling modes

Cho, Il Yong,Seo, HyeongJoon,Kim, Dongwoo,Kim, Yongchan Elsevier 2016 ENERGY Vol.112 No.-

<P><B>Abstract</B></P> <P>The cooling and heating performances of R410A and R32 multi-heat pumps with a sub-cooler vapor injection (SCVI) were measured and compared with variations in the outdoor temperature, compressor speed, and injection ratio. Optimum injection ratios were determined to obtain maximum cooling and heating performances at a given operating condition. In the cooling mode with the optimum injection ratios, the R410A and R32 multi-heat pumps with vapor injection showed 2.1%–6.3% higher cooling capacity than those without vapor injection. In the heating mode, the R410A and R32 multi-heat pumps with vapor injection showed 7.5%–13.9% higher heating capacity than those without vapor injection, while showing 2.6%–7.0% and 1.1%–4.7% higher COPs, respectively. In addition, the SCVI cycle was more effective for improving the cooling and heating performances under extremely hot and cold weather conditions, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The performances of the R410A and R32 multi-heat pumps were measured. </LI> <LI> Vapor injection (SCVI) was adopted in the R410A and R32 multi-heat pumps. </LI> <LI> Optimum injection ratios were determined to obtain the maximum performance. </LI> <LI> Comparison was conducted according to outdoor temperature and injection ratio. </LI> <LI> Vapor injection was more effective under extremely hot and cold conditions. </LI> </UL> </P>