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Park Cheol Wung,Oh Jacob Yoong-Leong 대한척추외과학회 2024 Asian Spine Journal Vol.18 No.4
The introduction of endoscopic spine surgery has led to a paradigm shift in the treatment of spinal disorders. In particular, biportal endoscopic surgery has gained traction for its wider visual field and improved the maneuverability of instruments, familiar anatomy, and costeffectiveness. In this study, we describe our en bloc removal of the ligamentum flavum using a “butterfly” technique. This approach had several advantages: (1) The flavum serves as a protective barrier for the dura during drilling. (2) There is less epidural bleeding, which provides (3) better visualization. (4) In an inadvertent durotomy, this usually occurs later in the procedure, which is more manageable than the early stages of decompression. Biportal decompression for spinal stenosis can be performed using an en bloc ligamentum flavum removal technique that is safe, reproducible, and efficient. A systematic approach will help early adopters overcome the steep learning curve.
박철웅 ( Cheol-wung Park ),김양기 ( Yang-gi Kim ),박송인 ( Song-in Park ) 한국환경기술학회 2016 한국환경기술학회지 Vol.17 No.3
There are 183 emergency facilities of water supply in Jeollanam-do, 105 facilities are used as a drinking water. The characteristics of emergency facilities of water supply used a drinking water were analyzed by investigating the result of water examination from 2011 to 2015. The rate of excess standard was 25.0%, the excess standard of germ items was 80.9%. Among 105 facilities, there was a water storage tank at 44 facilities, an emergency generator at 54 facilities, a disinfection facilities at 5 facilities. The facilities were categorized according to the installation of period, 2 facilities were less than five years, 4 facilities were less than ten years more than five years, 20 facilities were less than fifteen years more than ten years, 42 facilities were less than twenty years more than fifteen years, 37 facilities were more than twenty years. The person for emergency facilities of water supply in charge of the work period was average 8.7 month, a budget per a facility was 2,700,000 won. All facilities were within the standard for Uranium, 3 facilities were more than 10 ㎍/L. For effective management of emergency water supply facilities, the budget for maintenance and the periodic training for person are needed.
박철웅(Choel-Wung Park),박철호(Cheol-Ho Park) 한국산업경제학회 2018 산업경제연구 Vol.31 No.4
본 연구는 최근의 월별 시계열 자료를 이용하여 오차수정모형을 통해 산업용 천연가스의 전국 및 권역별 수요함수를 추정하였다. 구체적으로, 최근의 구조변화시점(2012년 5월) 이후 시계열 자료에 대해 공적분 기법(FM-OLS)을 적용하여 전국과 권역별 가격 및 소득탄력성을 추정하고, 오차수정모형을 통해 기존연구에서 사용된 모형과의 예측오차를 비교하였다. 구조변화시점 이후에는 산업용 천연가스 소비에 대한 거시경제변수의 영향이 크게 감소한 것으로 나타났기 때문에, 석유류 대비 산업용 천연가스의 상대가격, 기온효과, 가스수요산업지수 등으로 설명변수를 구성하였다. 공적분 회귀모형으로 전국 수요함수를 추정한 결과, 소득탄력성과 가격탄력성은 비탄력적이었으며 각각 0.465와 –0.227로 나타났다. 권역별 수요함수의 경우 상대가격은 수도권의 산업용 천연가스 소비에 영향을 미치지 못하였으며, 소득탄력성은 수도권이 지방권에 비해 작은 반면 기온효과는 큰 것으로 분석되었다. 또한 오차수정모형을 이용한 표본외 예측실험 결과, 전국 수요함수에 대한 월별 평균예측오차율(1.7%)이 기존의 다중회귀모형의 평균예측오차율(6.0%)에 비해 크게 개선된 것으로 나타났다. This study estimates the demand function of industrial natural gas by country and region through error correction models. Specifically, we estimate the price and income elasticities of the nation and the region by applying the cointegration method(FM-OLS) to the time series data since the recent structural change(May 2012). As the impact of macroeconomic variables on industrial natural gas consumption has greatly decreased since the time of structural change, explanatory variables were composed of relative prices of industrial natural gas compared to petroleum, temperature effect, the gas demand industry index, etc. As a result of estimating the national demand function as a cointegration regression model, income elasticity and price elasticity appeared to be inelastic by 0.465 and -0.227, respectively. In the case of demand function by region, the relative price has no effect on the industrial natural gas consumption in the metropolitan area, and the income elasticity in the metropolitan area is smaller than that in the local area. But the temperature effect is larger in the metropolitan area. In addition, the result of an out-of-sample experiment for the aggregate demand function indicated that the mean absolute percentage error(1.7%) of the error correction model was much smaller than that(6.0%) of the conventional multiple regression model.
( Hwan Cheol Kim ),( Choong Do Park ),( Jeong Wung Jeong ),( In Jin Shon ) 대한금속재료학회 2003 METALS AND MATERIALS International Vol.9 No.2
Dense MoSi2 compound was synthesized with the high-frequency induction heated combustion synthesis method in one step from elemental powders of Mo and Si within 2 min. Simultaneous combustion synthesis and densification were carried out under the combined effects of induced current and mechanical pressure. A highly dense MoSi2 with a relative density of up to 98 % was produced with simultaneous application of 60 Mpa pressure and induced current. The percentages of the total shrinkage occurring before and during the synthesis reaction were 16 % and 53 %, respectively. The average grain size was about 15 mm and a slight amount of Mo5Si3 was observed at the boundaries of the MoSi2 grains. The fracture toughness and hardness values obtained were 3.5 Mpa·m 1/2 and 1050 kg/㎟, respectively. These values were similar to those of commercial ones.
O/W 에멀젼 입자의 크기에 미치는 Direct 유화법과 Invert유화법의 효과
김철훈 ( Cheol-hun Kim ),박재길 ( Jae-kiel Park ),황정웅 ( Jeong-wung Hwang ),허정림 ( Jung-rim Haw ) 대한화장품학회 1994 대한화장품학회지 Vol.20 No.1
유화제로 polyoxyethylene(20)sorbitan monostearate, sorbitan sesquioleate을 혼합 사용하고, 분산상으로 liquid paraffin, 연속상으로 deionized water를 원료로 사용하여 Direct유화법을 이용한 전상법과 Invert유화법을 3가지 단계의 제조방법으로 나누어서 O/W에멀젼을 제조하였고, 각 단계 전상유화법에서 첨가되는 물의 양에 따른 최종 O/W에멀젼의 입자크기변화를 관찰하였다. Direct유화법을 이용한 2단계 전상유화법을 사용하여 제조한 결과, 미세하고 균일한 입자를 갖는 O/W에멀젼은 W/O에서 (W/O)W 이중에멀젼으로의 전환 단계를 거쳐야만 생성됨을 알 수 있었다. Invert유화법을 사용한 3단계전상유화법은 W/O 에서 일종의 Pseudomicroemulsion gel상을 거쳐 미세하고 균일한 O/W유화 입자가 얻어졌다. 3단계 전상법이 2단계 전상법보다 더 미세하고 균일한 입자를 생성하였다. 실험에서 사용한 모든 유화법에서 혼합유화제의 HLB가 10.0 - 10.8 영역에서 가장 미세한 에멀젼입자가 형성되었다. 이 HLB영역에서 혼합유화제가 용해되어있는 오일상에 첨가되어 가용화되는 물의 양이 최대로 많았으며, 최대 가용화 물양을 갖는 유화제의 조성에서 가장 미세하고 균일한 입자가 얻어졌다. O/W emulsions with mixed nonionic surfactants(polyoxyethylene(20)sorbitan monostearate/sorbitan sesquioleate), liquid paraffin, water prepared by direct inversion emulisification method and continuous inversion emulsification Method. The one-step, two-step and three-step phase inversion emulsification method were used in experiments. Effect of added water on droplet size of final O/W emulsions which is prepared by phase inversion emulsification method were investigated. In direct inversion emulsification method(two-step emulsification method), fine and homogeneous droplets of OIW emulsions were formed after phase inversion steps i.e. ,W/O - (W/O) If double emulsion - O/W emulsion. In continuous inversion emulsification method(three-step emulsification method), fine and homogeneous O/W emulsion were formed after phase inversion steps i.e., W/O - pseudomicroemulsion - O/W. By latter method, more Fine and homogenuous droplets were formed than former method. 10-10, 8 HLB region of mixed non-ionic surfactants could produce most fine droplets. This HLB region had maximum values of solubilization water and This HLB value of mixed nonionic surfactants produced fine and homogenuous droplets.
Cheal Wung Huh,Nak Hoon Son,Young Hoon Youn,Da Hyun Jung,Min Kyung Kim,Eun Jeong Gong,Kyu Chan Huh,Seung Young Kim,Moo In Park,Ju Yup Lee,Joong Goo Kwon,Jae Hak Kim,Cheol Min Shin,Kee Wook Jung,Su Jin 대한소화기 기능성질환∙운동학회 2023 Journal of Neurogastroenterology and Motility (JNM Vol.29 No.4
Background/AimsGastroesophageal reflux disease (GERD) is a common chronic gastrointestinal disorder that typically requires long-term maintenance therapy. However, little is known about patient preferences and satisfaction and real-world prescription patterns regarding maintenance therapy for GERD. MethodsThis observational, cross-sectional, multicenter study involved patients from 18 referral hospitals in Korea. We surveyed patients who had been prescribed proton pump inhibitors (PPIs) for GERD for at least 90 days with a minimum follow-up duration of 1 year. The main outcome was overall patient satisfaction with different maintenance therapy modalities. ResultsA total of 197 patients were enrolled. Overall patient satisfaction, patient preferences, and GERD health-related quality of life scores did not significantly differ among the maintenance therapy modality groups. However, the on-demand therapy group experienced a significantly longer disease duration than the continuous therapy group. The continuous therapy group demonstrated a lower level of awareness of potential adverse effects associated with PPIs than the on-demand therapy group but received higher doses of PPIs than the on-demand therapy group. The prescribed doses of PPIs also varied based on the phenotype of GERD, with higher doses prescribed for non-erosive reflux disease than erosive reflux disease. ConclusionAlthough overall patient satisfaction did not significantly differ among the different PPI maintenance therapy modality groups, awareness of potential adverse effects was significantly different between the on-demand and continuous therapy groups.
Yoo Beom Seok,Park Cheol Wung,Jung Jae-Kyun,Yoon Jae-Eon,An Tae-Yong,Kim Byung-Kwan,Lee Jin-Seong 대한통증연구학회 2024 International Journal of Pain Vol.15 No.1
Background: PF-72 (TGel Bio Co. Ltd., Seoul, Republic of Korea) is a type of temperature-responsive hydrogel. Methods: The eligible patients (n = 72) were randomized to either the trial group (n = 35; PF-72 mixed with 0.75% ropivacaine hydrochloride) or the control group (n = 37; patient-controlled anesthesia). We compared the amount of used rescue analgesics, numeric rating scale (NRS) pain scores, the cumulative area under the curve (AUC0-72) of NRS pain scores and incidences of treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs). We estimated time-to-events (TTEs). Results: There were significant differences in the amount of used analgesics and NRS pain scores between the two groups at 3, 6, 24, 48 and 72 hours postoperatively (P = 0.000). There were also significant differences in AUC0-6, AUC0-24, AUC0-48 and AUC0-72 of NRS pain scores between the two groups (P = 0.000). There was a significant difference in the proportion of the patients presenting with no pain between the two groups at 3, 6 and 24 hours postoperatively (P = 0.000). There were no significant differences in the incidences of TEAEs and SAEs between the two groups (P > 0.05). TTEs are estimated at 7.486 ± 2.758 (95% confidence interval [CI] 2.081 ± 12.890) hr in the trial group and 9.324 ± 2.488 (95% CI 4.448 ± 14.200) hr in the control group. Conclusions: PF-72 mixed with 0.75% ropivacaine hydrochloride is an effective, safe modality in alleviating pain in the patients undergoing elective arthroscopic shoulder surgery
신윤철(Shin Yun Cheol),김현웅(Kim Hyun Wung),방정석(Bang Jeong Seok),박종연(Jongyoun Park),김경석(Kim Kyungseok),전성민(Seongmin Jeon) 한국추진공학회 2018 한국추진공학회 학술대회논문집 Vol.2018 No.12
본 논문은 한국형발사체 75톤 액체 로켓 엔진에 적용되는 고압유연배관 기술 개발에 대해 기술한다. 고압유연배관은 GIMBAL BELLOWS라고도 하며, 연소기 짐벌 방식을 사용하는 한국형 발사체에서 관절의 역할을 하는 기능을 가지고 있다. 75톤 액체 로켓 엔진의 고압배관을 연결하며, 연소기 짐벌 시배관의 기능을 유지하면서 연소기 짐벌을 가능하게 한다. 고압 유연 배관은 1단 엔진과 2단 엔진에서 산화제나 연료를 터보펌프로부터 연소실로 전달하는 고압배관의 구성 품으로서 극저온상태를 견뎌내고, 높은 작동압력 이상을 만족하여야 하며, 연소기 짐벌 시 짐벌 각도의 요구조건을 만족하여야 한다. 본 논문에서는 고압유연배관의 요구 조건을 만족하도록 제작한 기술 개발에 대하여 소개한다. This paper describes the development of high pressure gimbal bellows technology for 75ton liquid rocket engine of Korean launch vehicle. High pressure flexible house is also called GIMBAL BELLOWS, and it acts as a join of Korean Launch vehicle using the combustor gimbal method. The high pressure gimbal bellows enables a combustor gimbal with a 75ton liquid rocket engine maintaining the function of piping when the combustor gimbals behavior. High pressure gimbal bellows is a high pressure piping component that convey oxidizer and fuel from a turbo pump to a combustion chamber in a 1st stage engine and a 2nd stage engine and satisfies a cryogenic condition and high operating pressure. Also, the gimbal angle requirement of the combustor gimbal behavior must be satisfied. In this paper, we introduce the development technology which was manufactured to satisfy the requirements of high pressure gimbal bellows.