Appropriate angle and depth in thoracic transforaminal epidural block in Koreans

노찬,이원형,고영권,이선열,김여정,이승훈,정춘호,강혜민 대한마취통증의학회 2018 Anesthesia and pain medicine Vol.13 No.4

Background: Selective transforaminal epidural block has come to the for as a targetspecific modality in the treatment and diagnosis of spinal pain. Thoracic transforaminal epidural block (TTFEB) has the associated risk of pneumothorax. This article describes a retrospective study conducted using computed tomography (CT) imaging to investigate the TTFEB angle and depth appropriate to minimize the risk of pneumothorax in Koreans. Methods: The subjects of the present study were 100 randomly selected patients between 50 and 70 years of age found be free of thoracic disease according to chest CT performed in the present hospital. On the chest CT, the superior, middle, and inferior thoracic vertebrae were observed at the T2, T7, and T11 levels, respectively. Results: The average distance and the needle insertion angle from the skin point at which the needle may be inserted without piercing the lung to the intervertebral foramen were 117.8 ± 12.1 mm and 58.1 ± 6.1° at the T2 level, 85.6 ± 10.0 mm and 61.7 ± 4.3° at the T7 level, and 94.3 ± 8.7 mm and 64.4 ± 7.0° at the T11 level, respectively. Conclusions: The needle insertion at the point further than 40 mm, on the upper, middle thorax, if the needle pass from the inner vertebral body to lamina, it could be safer. However, on the lower thorax, needle could pierce the lung though the needle start from the inner vertebral body. Thus, it can be safer if the needle pass toward the exterior margin of lamina.

OWC 파력발전용 전력변환장치의 빠른 동특성을 위한 모델 예측 전류 제어 기법에 관한 연구

노찬,최종수,곽상신,김경환 한국해양환경·에너지학회 2020 한국해양환경·에너지학회지 Vol.23 No.1

The control using the power converter for wave power generation has been recently studied because it can obtain a fast dynamic response. However, it is difficult to get a transient response because of the energy characteristic of the wave energy that the conventional pulse-width modulation (PWM) method based on proportional integral control (PI-Control) for controlling the power converter has been widely used. Instead of using the optimal switching state during each sampling step, the control is performed by using various switching states located near the reference voltage vector, so that the reference current can not follow in a short time when the transient state occurs. Therefore, in this paper, Model Predictive Current Control (MPCC) is proposed with fast dynamic characteristics using model of power converter for wave power generation. The proposed method predicts the current of the next step through the model of the power converter, constructs the cost function using the predicted current and the reference current, and selects one optimal switching state during each sampling step. As in the conventional method, instead of using various switching states for each sampling, a fast transient response can be obtained because only one optimal voltage vector is used, that is, the optimal switching state, which is closest to the reference voltage vector. To verify the performance of the proposed method, the simulation is performed through the PSIM and the conventional PI-based PWM method (PI-PWM) and the proposed method demonstrate the performance of the proposed method through comparison of steady state and various transient states. 전력변환장치를 이용한 제어는 빠른 응답을 얻을 수 있기 때문에 최근에 연구가 많이 되고 있다. 하지만 기존에 파력발전용 전력변환장치 제어를 위한 비례적분제어(Proportional Integral control, PI-Control) 기반의 펄스폭변조기법(Pulse Width Modulation, PWM)은 입력 에너지가 수초단위로 변화하는 파랑에너지 특성상 빠른 과도 응답을 얻기가 어렵다. 매 샘플링 스텝마다 최적의 스위칭 상태를 사용하는 것이 아니라 기준 전압 벡터 인근에 위치한 다양한 스위칭 상태를 이용해서 제어하기 때문에 과도 상태가 발생 했을 때 기준 전류를 빠른 시간 안에 추종할 수 없게 한다. 그래서 본 논문에서는 파력발전용 전력변환장치의 모델을 이용한 전류예측제어(Model Predictive Current Control, MPCC)를 통해 빠른 동특성을 갖는 최적제어기법을 제안한다. 제안하는 방법은 전력변환장치의 모델을 통한 다음 스텝의 전류를 예측하고, 예측된 전류와 기준 전류를 이용해 비용 함수(Cost Function)을 구성한 다음 매 샘플링 스텝마다 최적의 스위칭 상태 하나를 선택한다. 기존의 방법처럼 매 샘플링 마다 다양한 스위칭 상태를 사용하는 것이 아닌 기준 전압 벡터와 가장 인접한 최적의 전압 벡터 즉 최적의 스위칭 상태 하나만 사용하기 때문에 빠른 과도 응답을 얻을 수 있다. 제안하는 방법의 제어기 성능을 검증하기 위해 PSIM을 이용해 시뮬레이션을 진행하였고, 기존의 PI기반의 PWM방법(PI-PWM)과 제안하는 방법을 정상상태와 다양한 과도상태 비교 분석을 통해 제안하는 방법의 성능을 입증한다.

파력발전 연계형 마이크로그리드를 위한 에너지저장장치 운용 알고리즘 검증에 관한 연구

노찬,임창혁,김경환,홍기용,신승호 한국해양환경·에너지학회 2020 한국해양환경·에너지학회지 Vol.23 No.2

Since wave energy converter is highly volatile due to the nature of input energy, difficulties may arise in directly connecting to the system. In particular, in an unstable system such as an island region, the instability of the system may be increased by directly linking renewable energy with high volatility. Accordingly, in order to apply wave power to island systems, an energy storage system capable of reducing output variability is required. In this paper, we verify the operation algorithm of the energy storage system in connection with wave energy converter linked microgrid for application to the island region. First of all, in order to verify the operation algorithm of the energy storage system connected to the wave power generation for the island area, we conducted system modeling for the island area, power load modeling, energy storage device modeling, and modeling of the wave power generation device and simulated using Matlab/Simulink. Proceeded. In addition, the characteristics of microgrid linked to wave energy converter were analyzed through various operational algorithms for optimal operation of the distribution network in connection with wave power generation, suitability for accidents, failure simulation, and wave power generation. The operating algorithm of the energy storage device for the wave power-linked microgrid was constructed based on StateFlow of Matlab, and OPAL-RT was applied for real-time simulation. 파력발전은 입력에너지 특성상 변동성이 크기 때문에 직접적으로 계통에 연계하는 것에 대해서 어려움이 발생할 수 있다. 특히 도서지역과 같이 불안정한 계통에서는 변동성이 큰 재생에너지를 직접적으로 연계하면 계통의 불안정성이 더욱 커질 수 있다. 이에 따라 도서지역 계통에 파력발전을 적용하기 위해서는 출력 변동성을 저감시킬 수 있는 에너지저장장치가 필요하다. 본 논문에서는 도서지역에 적용하기 위한 파력발전을 연계한 마이크로그리드의 에너지저장장치의 운용 알고리즘에 대해서 검증한다. 우선적으로 도서지역에 대한 파력발전 연계형 에너지저장장치의 운용 알고리즘을 검증하기 위해서 도서지역 계통 모델링, 전력 부하 모델링, 에너지저장장치 모델링, 파력발전장치 모델링을 진행하였고, Matlab/Simulink를 이용해서 시뮬레이션을 진행하였다. 또한 파력발전 연계의 적합성, 사고 및 고장 모의, 파력발전을 연계한 배전망 최적 운용을 위한 다양한 운용알고리즘을 수행을 통해 파력발전을 연계한 마이크로그리드의 특성을 분석하였다. 파력발전 연계형 마이크로그리드를 위한 에너지저장장치의 운용 알고리즘은 Matlab의 StateFlow기반으로 구성하였고, 실시간 시뮬레이션을 위해서 OPAL-RT를 적용하였다.

Effect of dexmedetomidine on endotracheal intubating conditions during endotracheal intubation without neuromuscular blocker following propofol/remifentanil

노찬,고영권,김윤희,임채성,정우석,송승현,송승현 대한마취통증의학회 2017 Anesthesia and pain medicine Vol.12 No.1

Background: In the present study, we investigated the effect of dexmedetomidine on the intubating conditions and hemodynamic changes during endotracheal intubation following anesthetic induction performed using propofol and remifentanil without a neuromuscular blocking agent. Methods: We selected 70 adult patients aged 20 to 65 years scheduled to undergo general anesthesia. Induction was performed using 2 mg/kg of propofol and 1.5 g/kg of remifentanil. The patients were divided into two groups, a dexmedetomidine group (Group D) and a control group (Group C). Group D received an infusion of dexmedetomidine 1 g/kg for 10 minutes before induction, and Group C received the same volume of normal saline infused in the same manner. Intubating conditions were evaluated and blood pressure and heart rate were recorded at various time points to assess hemodynamic stability. Results: Intubating conditions were evaluated as excellent for 34 patients and good for 1 patient in Group D, and excellent for 4 patients, good for 20 patients, poor for 4 patients, and bad for 7 patients in Group C (P < 0.001). The heart rate was significantly lower in Group D than in Group C at all measurement times. The mean arterial blood pressure was significantly lower in Group C than in Group D at 10 minutes after dexmedetomidine administration (P = 0.049), after the induction of anesthesia (P < 0.001), immediately after endotracheal intubation (P = 0.008), and 3 minutes after endotracheal intubation (P < 0.001). Conclusions: Dexmedetomidine 1 g/kg improved the intubating conditions and stabilized hemodynamic changes following anesthetic induction performed using propofol 2 mg/kg and remifentanil 1.5 g/kg without a neuromuscular blocking agent.

진동수주형 파력발전시스템의 전력변환장치 제어를 위한 PWM 기법 비교

노찬(Roh Chan),김경환(Kyong-Hwan Kim),김재혁(Jae Hyuck Kim),홍기용(Keyyong Hong) 한국해양환경·에너지학회 2019 한국해양환경·에너지학회지 Vol.22 No.2

인공지능 기반 해양쓰레기 이동 예측 모델 적용 방안 연구

노찬(Chan ROH),임창혁(Chang Hyuck LIM),안현정(Hyeonjeong AHN),방기영(Ki-Young BANG),오정환(Jeong-Hwan OH) 한국해양환경·에너지학회 2021 한국해양환경·에너지학회 학술대회논문집 Vol.2021 No.10

해양쓰레기 수거 및 관리 전략 수립을 위해 해양쓰레기의 이동 및 분포를 파악하는 것은 매우 중요하다. 해양쓰레기 이동 및 분포는 해류, 조류 및 바람 등 해양기상 환경에 주로 영향을 받는 복잡한 현상이다. 해양쓰레기 이동 및 분포를 예측하는데 입자추적 기법을 이용한 수치모델들이 주로 사용되어 왔고, 모델 결과의 정확성 및 신뢰성을 검증하기 위해 주로 추적부이 관측자료가 사용하였다. 최근, 인공지능 기술의 발전으로 해양환경 모니터링, 해양환경 예측모델 분야 등에 활용되고 있는 추세이다. 인공지능 기법을 적용하기 위해서는 무엇보다 예측결과를 검증하기 위한 많은 관측자료가 요구된다. 하지만, 해양쓰레기 이동 예측에 인공지능 기법을 적용하는데 활용가능한 추적부이 관측자료는 매우 제한적이다. 그러므로 본 연구에서는 제한적인 관측자료를 활용하여 인공지능 기법 적용 방안를 검토하고자 한다. 인공지능 기법 적용 방안을 검토하기 위해서 본 연구에서는 딥러닝 알고리즘을 적용해서 분석을 수행하였다. 딥러닝 알고리즘은 개별 신경망 구조인 Multilayer-perceptron(MLP) 알고리즘과 순환 신경망구조인 Long-short term memory(LSTM) 알고리즘을 적용하였다. 이러한 방법을 기반으로 본 연구의 타당성을 검증하였다. It is very important to understand the movement and distribution of marine debris in order to establish a strategy for collecting and managing marine debris. The movement and distribution of marine debris is a complex phenomenon that is mainly influenced by the marine meteorological environment such as ocean currents, tidal currents and winds. Numerical models using particle tracking techniques have been mainly used to predict the movement and distribution of marine debris. In order to verify the accuracy and reliability of the model results, observation data from the tracking buoy were mainly used. Recently, with the development of artificial intelligence technology, it is being used in marine environment monitoring and marine environment prediction model results. In order to apply artificial intelligence techniques, a lot of observational data is required to verify the prediction model results. However, the tracking buoy observation data available for applying artificial intelligence techniques to the prediction of marine debris movement are limited. Therefore, this study intends to review the application of artificial intelligence techniques using limited observational data. In order to examine the application of artificial intelligence techniques, deep learning algorithms were applied to perform analysis. The deep learning algorithm applied the Multilayer-perceptron (MLP) algorithm, which is an individual neural network structure, and the Long-short term memory (LSTM) algorithm, which is a recurrent neural network structure. Based on these methods, the validity of this study was verified.

철도 차량 내 미세먼지 저감 방안에 관한 연구

노찬(Chan Roh),김재문(Jae-Moon Kim) 대한전기학회 2014 대한전기학회 학술대회 논문집 Vol.2014 No.7

모델예측제어 기반 파력발전용 4-선식 인버터들의 출력 성능 비교

노찬(Chan Roh) 한국해양환경·에너지학회 2022 한국해양환경·에너지학회지 Vol.25 No.4

Cascaded H-Bridge 멀티레벨 인버터를 위한 개선된 모델 예측 제어 방법

노찬(Chan Roh),김재창(Jae-Chang Kim),곽상신(Sangshin Kwak) 대한전기학회 2018 전기학회논문지 Vol.67 No.7

In this paper, an improved model predictive control (MPC) method is proposed, which reduces the amount of calculations caused by the increased number of candidate voltage vectors with the increased voltage level in multi-level inverters. When the conventional MPC method is used for multi-level inverters, all candidate voltage vectors are considered to predict the next-step current value. However, in the case that the sampling time is short, increased voltage level makes it difficult to consider the all candidate voltage vectors. In this paper, the improved MPC method which can get a fast transient response is proposed with a small amount of the computation by adding new candidate voltage vectors that are set to find the optimal vector. As a result, the proposed method shows faster transient response than the method that considers the adjacent vectors and reduces the computational burden compared to the method that considers the whole voltage vector. the performance of the proposed method is verified through simulations and experiments.

난류강도에 따른 FAST 기반 풍력발전장치 연간발전량의 영향 연구

노찬(Roh Chan),안현정(Hyen-Jeong Ahn),하윤진(Yoon-Jin Ha),박세완(Se-Wan Park),김경환(Kyong-Hwan Kim) 한국해양환경·에너지학회 2021 한국해양환경·에너지학회 학술대회논문집 Vol.2021 No.5

본 연구에서는 풍황자원의 난류 강도에 따른 부유식 풍력발전장치의 연간발전량의 영향에 대해서 분석하였다. 풍력발전장치는 난류강도에 따라서 동일한 평균 풍속에서도 출력 특성이 변화할 수 있기 때문에 난류강도에 따른 출력특성 분석이 필요하다. 특히 부유식 풍력발전장치는 난류강도에 따라서 피치제어기의 성능이 변화하고 이에 따라 출력 특성이 변화하기 때문에 기존의 육상 풍력발전장치보다 난류강도는 출력특성에 더 큰 영향을 준다. 난류강도는 IEC turbulence characteristic에 따라서 A, B, C 세가지로 분류하였고, 이에 따른 발전성능의 차이에 대해서 분석을 진행하였다. 본 연구에서는 NREL의 FAST를 이용해서 부유식 풍력발전장치의 연간발전량을 분석하였고, 대상 모델은 NREL의 5MW급 터빈과 Semi-OC4 플랫폼을 적용하였다. In this study, the effect of annual power generation of a floating wind power generator according to the turbulence intensity of wind turbine resources was analyzed. Wind power generators need to analyze the output characteristics according to the turbulence intensity because the output characteristics can be changed even at the same average wind speed according to the turbulence intensity. In particular, since the performance of the pitch controller changes according to the turbulence intensity of the floating wind turbine and the output characteristics change accordingly, the turbulence intensity has a greater influence on the output characteristics than the conventional onshore wind turbine generator. Turbulence intensity was classified into A, B, and C according to IEC turbulence characteristics, and the difference in power generation performance was analyzed accordingly. In this study, the annual generation of floating wind turbines was analyzed using NREL's FAST, and the target model was NREL's 5MW class turbine and Semi-OC4 platform.