• 한국해양공학회지
• /
• 제20권1호
• /
• pp.20-25
• /
• 2006

This paper deals with the design and aerodynamic analysis of a so-called 'ring-type' impulse turbine for wave energy conversion. Numerical analysis was performed using the CFD cock, FLUENT. The main idea of the proposed turbine rotor was to minimize the adverse effect of tip clearance of the turbine blade; the design was borrowed from a ducted propeller with connected ring tip for special purpose marine vehicles. Results show that the efficiency increases up to $10\%$, depending on flaw coefficient, with the higher flaw coefficient yielding better efficiency. Decrease of input coefficient CA was the main reason for higher efficiency. Performance of ring-type rotor at various design parameters, as well as flaw conditions, was investigated, and the advantages and the disadvantages of the present impulse turbine were also discussed.

• 대한기계학회논문집B
• /
• 제27권1호
• /
• pp.84-94
• /
• 2003

It is known that tip clearance flows reduce the pressure rise, flow range and efficiency of the turbomachinery. So, the clear understanding about flow fields in the tip region is needed to efficiently design the turbomachinery. The Navier-Stokes code with the proper treatment of the boundary conditions has been developed to analyze the three-dimensional steady viscous flow fields in the transonic rotating blades and a numerical study has been conducted to investigate the detail flow physics in the tip region of transonic rotor, NASA Rotor 67. The computational results in the tip region of transonic rotors show the leakage vortices, leakage flow from pressure side to suction side and their interaction with a shock. Depen ding on the operating conditions, toad distributions and the position of shock-wave on the blade surface are very different close to the blade tip of the transonic compressor rotor. The load distribution and the shock-wave position close to the blade tip had the close relationship with the starting position of leakage vortex and the direction of leakage flow.

• 소음진동
• /
• 제7권6호
• /
• pp.993-1000
• /
• 1997

This paper presents a new technique of mathematical treatment using a finite element model for analyzing the vibration of the towed line array. Since the towed line array has the axisymmetricity, axisymmetric elements are used in finite element modeling for the towed array structure. The fluid-structure interaction is also considered. The array consists of a series of identical substructures which can include internal structures such as spacers, hydrophones and ropes. That periodicity of substrucutres permits the substructure synthesis technique using characteristic wave guide for analyzing the response of towed array system. This synthesis technique can reduce the cost of computing the array response. It is suggested that a response of towed array can be computed by the finite element method and substructure synthesis technique using wave guide. Several experiments for towed array were performed to verify the present computation technique. The predicted vibration for the towed array shows good agreement with the measured result.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제37회 추계학술대회논문집
• /
• pp.263-267
• /
• 2011

본 연구는 에틸렌-공기 혼합물로 채워져 있는 굽은 관에서의 충격파와 화염의 상호 작용, 화염 가속, 연소폭발천이 현상을 수치적으로 살펴보았다. 여기서 사용되는 모델은 지배방정식으로 Navier-Stokes 방정식과 경계조건 처리 방법으로 ghost fluid 기법을 사용하였다. 굽은 관에서 여러 충격파 강도를 이용한 모델링을 통하여 화염과 강한 충격파의 충돌에 의한 열점 생성과 화염 전파의 가속 현상을 확인하였으며 추가적으로 평균 화학적 열 발생률이 대략 20 MJ/($g{\cdot}s$)이 되는 지점에서 최초 폭굉이 발생한다는 것을 확인하였다. 즉, 우리는 복잡한 형상에 의한 효과를 포함하는 수치적 계산 결과를 기반으로 관에서의 강한 충격파, 충격파와 화염의 상호 작용, 열점, 연소폭발천이 현상 등의 발생을 확인하였다.

• 한국해안해양공학회지
• /
• 제19권3호
• /
• pp.205-212
• /
• 2007

파랑변형을 계산하기 위한 $Pad{\acute{e}}$ 근사에 의한 포물형 근사모형들을 분석하였다. 기존 포물형 근사모형 보다 정밀도가 높은 $Pad{\acute{e}}(2,2)$ 근사모형을 제시하였고 일정 경사면에 대한 수치실험을 통해 본 모형은 기존의 모형보다 입사각이 큰 경우에도 성공적으로 적용할 수 있음을 입증하였다.

• 한국염색가공학회지
• /
• 제26권4호
• /
• pp.353-362
• /
• 2014

This study attempted to determine the effects of fermented green tea extracts on hair by using them in a perm. For this, hair is bleached, and then the fermented green tea extracts and water were supplied to the hair using a mist sprayer. Then the hair was permed, and hair damage was tested. Regarding hair moisture levels and wave formation, specifically, the morphological changes of hair were investigated with the Scanning Electron Microscope(SEM). The study results found the following. In terms of wave formation, the fermented green tea extract-based perm was much better than the general perm. In addition, hair bleaching was more serious in the latter. According to analysis on hair moisture using SEM, hair damage was more prevalent in the general perm as well. Therefore, it was confirmed that green tea extract-based perms cause less damage to the cuticle. In other words, the potential of fermented green tea extracts as a hair cosmetics material was discovered. Furthermore, it appears that the study results contribute to the development of low-irritating scalp and hair care products using the anti-inflammatory and antimicrobial properties of the fermented green tea extracts.

• 한국임상수의학회지
• /
• 제34권3호
• /
• pp.178-184
• /
• 2017

The aim of this study was to determine whether Hounsfield units (HUs), volume, and various void parameters can predict stone fragility in extracorporeal shock wave lithotripsy (ESWL). HU, volume, porosity, number of voids/stone volume, and void distribution of 30 struvite stones were estimated using helical computed tomography (CT) and micro-CT. The number of shock waves necessary for full fragmentation was accepted as a measure of the stone fragility in ESWL. The correlations between the number of shock waves and the HU, volume, porosity, and number of voids/stone volume were examined. The number of shock waves of the two groups according to the void distribution was also compared. Stone volume correlated with the number of shock waves. Shell-patterned struvite stones were significantly less susceptible to fragmentation in ESWL than non-shell-patterned struvite stones. Stone volume and void distribution may be predictors of the outcome of ESWL treatment.

• 대한정형도수물리치료학회지
• /
• 제26권2호
• /
• pp.1-10
• /
• 2020

Background: This study aimed to investigate the effect of hold-relax and antagonist contraction (HR-AC) technique and Kinesio taping on pain changes in delayed-onset muscle soreness (DOMS) of 20's adults. Methods: Based on voluntary participation, 14 participants with induced-DOMS were randomly divided into control (non-treatment, n=7) and experiment group (HR-AC technique and kinesio taping, n=7). Measurement were used visual analogue scale (VAS), heart rate variability (HRV), and brain wave (alpha). There were 5 sets of the HR-AC technique application on the 5th day from the day of DOMS induction (rest for 30s between sets). Kinesio taping was applied to the same area after HR-AC. Results: The VAS showed significant changes according to the period and in the interaction between the period and the group (p<.01). HRV and alpha wave (Fp1) showed significant changes according to the period (p<.001). The analgesic effect was more rapid and continuous in the experimental group than in the control group. Conclusion: This study showed that the HR-AC technique and Kinesio taping are effective interventions for the management of pain and stress caused by DOMS.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제16권4호
• /
• pp.1209-1223
• /
• 2022

Blood pressure is one of the key physiological parameters for determining human health, and can prove whether human cardiovascular function is healthy or not. In general, what we call blood pressure refers to arterial blood pressure. Blood pressure fluctuates greatly and, due to the influence of various factors, even varies with each heartbeat. Therefore, achievement of continuous blood pressure measurement is particularly important for more accurate diagnosis. It is difficult to achieve long-term continuous blood pressure monitoring with traditional measurement methods due to the continuous wear of measuring instruments. On the other hand, radar technology is not easily affected by environmental factors and is capable of strong penetration. In this study, by using machine learning, tried to develop a linear blood pressure prediction model using data from a public database. The radar sensor evaluates the measured object, obtains the pulse waveform data, calculates the pulse transmission time, and obtains the blood pressure data through linear model regression analysis. Confirm its availability to facilitate follow-up research, such as integrating other sensors, collecting temperature, heartbeat, respiratory pulse and other data, and seeking medical treatment in time in case of abnormalities.

• Physical Therapy Rehabilitation Science
• /
• 제12권1호
• /
• pp.48-55
• /
• 2023

Objective: The purpose of this study is to compare the effects of extracorporeal shock wave therapy (ESWT) and injection therapy through qualitative and quantitative analysis by synthesizing randomized controlled trials (RCTs) conducted on patients with various shoulder diseases. Design: A systematic review and meta-analysis of randomized controlled trials Methods: This review conducted a literature search through international electronic databases in January 2023 to compare the effects of ESWT and injection therapy. Qualitative analysis was performed as a risk of bias tool, and quantitative analysis was synthesized with a random effect model to show the effect size as a standardized mean difference (SMD). Results: Five RCTs involving 298 individuals with shoulder disorders were included in this systematic review and meta-analysis. ESWT showed a moderate effect on pain (SMD=-0.44; 95% CI, -0.95 to 0.06) and a large effect on shoulder function (SMD =-0.81; 95% CI, -1.70 to 0.07) than injection therapy. A significant difference was found in the shoulder range of motion, showing a large effect size (SMD=1.50; 95% CI, 0.58 to 2.43). Conclusions: When considering treatment options for the management of patients complaining of shoulder disorders, it is appropriate to recommend ESWT first rather than injection therapy to increase the range of motion of the joint. In addition, ESWT is safe for pain control and shoulder function improvement, and a positive prognosis could be expected.