• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.327-330
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• 2006

공동부 위에 설치된 슬롯판을 이용한 경사충격파와 난류 경계층의 간섭유동의 피동제어에 관한 수치적 연구가 수행되었다. 얻어진 수치결과는 피토압력/벽압력 분포와 쉴리렌 유동가시화 등 동일한 경계조건에서 수행된 실험결과와 비교되었으며, 두 결과가 서로 잘 일치하고 있음이 확인되었다. 또한 슬롯의 위치와 개수, 슬롯의 각도 등 슬롯판의 다양한 형상변화가 간섭유동에 미치는 영향이 추가로 관찰되었다. 이러한 슬롯의 형상변화가 간섭유동에 미치는 영향을 정량적으로 파악하기 위하여, 간섭유동 후방의 피토압력 및 전압 변화, 경계층 특성변화, 그리고 슬롯판을 통하여 공동부 내부로 유출입하는 질량유량의 변화 등이 관찰되었다.

• 한국항공우주학회지
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• 제30권1호
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• pp.9-19
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• 2002

AUSMPW+의 해의 정확성은 음속의 정의와 밀접한 관계가 있다. 아음속, 천음속 그리고 초음속 유동 영역에서 제어면의 음속의 해의 정확성에 어떠한 영향을 미치는지 살펴보았다. AUSMPW+에서 정의된 음속의 특징은 충격파 포착시 정확성 향상과 엔트로피 조건을 만족시키기 위한 팽창충격과 현상을 제거로 요약될 수 있다. 수학적 증명과 수치실험을 통해 이를 확인할 수 있었다. 그리고 반응 기체로 확장하여 평형, 비평형 기체에 대해서도 충격파를 정확하게 포착할 수 있는 음속을 제시하였고 이를 여러 가지 수치 실험을 통해 확인하였다.

• 한국추진공학회지
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• 제11권2호
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• pp.18-25
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• 2007

공동부 위에 설치된 슬롯판을 이용한 경사충격파와 난류 경계충의 간섭유동의 피동제어에 관한 수치적 연구가 수행되었다. 수치해석에서 얻어진 결과는 간섭전방에서 압축성 난류경계층 이론을 잘 따르고 있었으며, 또한 벽압력 분포와 쉴리렌 유동가시화와 같은 실험결과와 서로 잘 일치하고 있음이 확인되었다. 또한 슬롯의 위치와 개수, 슬롯의 각도 등 슬롯판의 다양한 형상변화가 간섭유동 특성에 미치는 영향이 관찰되었으며, 간섭유동 후방의 전압변화, 경계층 특성변화, 그리고 슬롯판을 통하여 공동부로 순환하는 질량유량의 변화 등이 서로 비교분석 되었다.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2005년도 춘계학술발표대회 논문집
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• pp.271-272
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• 2005

As regards of designing, I chose a simple wall design of repeating pattern of vertical windows, rather than making the building as a glamourous obzet. This kind of approach was intended to pursue strong image of construction company, interchanging and communicating with its confused surrounding. Therefore, I boldly removed parts that I considered needless from the facade, and used simple and easy words clearly implying the organization. Lobby is the face of the building, but since the space is deep and narrow and the reality of lease should be considered, there was limit to give original image to the lobby. Instead, high ceiling is the biggest feature of this space. Doorae Engineering-Construction Corp. is young and energetic company. I wanted to highlight the young and energetic image of the company by crossing tore oblique piece of boards. This doesn't just has a simple function as ceiling, but also work as a major subject in the space. In addition of this powerful space of oblique lines, indirect lighting is used to emphasize the character of territory, continuity and deepness of the space. Character of territory that divides main and supplementary function and main and supplementary moving line is expressed by flow of dimension, and continuity and deepness of space is emphasized by indirect lighting flowing linearly through the crack between the ceiling and the wall.

• 한국정밀공학회지
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• 제21권6호
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• pp.28-34
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• 2004

The old technique of sandblasting which has been used for decoration of glass surface has recently been developed into a powder blasting technique for brittle materials such as glass, silicon and ceramics, capable of producing micro structures larger than 100${\mu}{\textrm}{m}$. In this study, we introduced oblique powder blasting, and investigated the effect of the impacting angle of particles, the scanning times and the stand-off distance on the surface roughness and the weight-loss rate of samples with no mask, and the wall profile and overetching of samples with different mask pattern in powder blasting of soda-lime glass. The varying parameters were the different impact angles between 50$^{\circ}$ and 90$^{\circ}$, scanning times of nozzle up to 40 and the stand-off distances 70mm and 100mm. The widths of mask pattern were 0.2mm, 0.5mm and 1mm. The powder was alumina sharp particles, WA #600. The mass flow rate of powder during the erosion test was fixed constant at 175g/min and the blasting pressure of powder at 0.2Mpa.

• 에너지공학
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• 제21권3호
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• pp.237-242
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• 2012

이 연구에서는 초음속 연소에서 발생하는 열폐색의 다양한 현상을 규명하기 위해 확대 축소 노즐 내부에서 열폐색에 의해 형성되는 2차원의 초음속의 비정상 유동장에 대한 수치해석 결과를 제시한다. 열폐색에 의해 야기되는 이동 충격파를 수치계산하기 위해 TVD 스킴을 이용하며, 노즐의 확대부의 일정영역에 가열을 통하여 열폐색이 발생할 수 있는 조건을 형성하고, 이 때 발생하는 천이현상을 분리부가 있는 경우와 없는 경우에 대해 불시동현상 발생속도, 비추력의 불안정성 등을 통해 비교, 설명한다. 분리부가 있는 경우가 없는 경우에 비해 열폐색에 의해 발생한 경사 충격파가 느린 속도로 상류측으로 이동하여 분리부의 설치가 엔진 불시동의 지연효과가 있음을 제시하였다.

• The Korean Journal of Pain
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• 제34권3호
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• pp.339-345
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• 2021

Background: Ultrasound-guided caudal epidural injection (CEI) is limited in that it cannot confirm drug distribution at the target site without fluoroscopy. We hypothesized that visualization of solution flow through the inter-laminar space of the lumbosacral spine using color Doppler ultrasound alone would allow for confirmation of drug distribution. Therefore, we aimed to prospectively evaluate the usefulness of this method by comparing the color Doppler image in the paramedian sagittal oblique view of the lumbosacral spine (LS-PSOV) with the distribution of the contrast medium observed during fluoroscopy. Methods: Sixty-five patients received a 10-mL CEI of solution containing contrast medium under ultrasound guidance. During injection, flow was observed in the LSPSOV using color Doppler ultrasonography, following which it was confirmed using fluoroscopy. The presence of contrast image at L5-S1 on fluoroscopy was defined as "successful CEI." We then calculated prediction accuracy for successful CEI using color Doppler ultrasonography in the LS-PSOV. We also investigated the correlation between the distribution levels measured via color Doppler and fluoroscopy. Results: Prediction accuracy with color Doppler ultrasonography was 96.9%. The sensitivity, specificity, positive predictive value, and negative predictive value were 96.7%, 100%, 100%, and 60.0%, respectively. In 52 of 65 patients (80%), the highest level at which contrast image was observed was the same for both color Doppler ultrasonography and fluoroscopy. Conclusions: Our findings demonstrate that color Doppler ultrasonography in the LS-PSOV is a new method for determining whether a drug solution reaches the lumbosacral region (i.e., the main target level) without the need for fluoroscopy.

• 대한조선학회논문집
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• 제42권6호
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• pp.593-600
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• 2005

The finite volume based multi-block RANS code, WAVIS developed at KRISO, is used to simulate the turbulent flow field around the KRISO container ship (KCS) and the modified KRISO tanker (KVLCC2M). The realizable k-$\varepsilon$ turbulence model with a wall function is employed for the turbulence closure. The free surface flow with and without propeller is mainly investigated for the KCS and the double model flow is concerned for the KVLCC2M which is obliquely towed in still water. The computed results are compared with the experimental data provided by CFD Tokyo Workshop 2005 in terms of wave profiles, hull surface pressure and wake distribution with and without propeller for the HCS and wake distribution and hydrodynamic forces and moments with various drift angles for the KVLCC2M.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.209-219
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• 2006

The supersonic combustion experiments are carried out using T3 free-piston shock tunnel. Different shock tube fill pressures have various inflow conditions. $15^{\circ}$ inclined hydrogen fuel injection is located before the cavity. Oblique shock is generated at the trailing edge of the cavity and reflects off the top and bottom wall. For non-reacting flow, static pressures in low equivalence ratio are similar to those in no fuel injection. As equivalence ratio is increased, static pressures are increased in the duct. In the similar equivalence ratio, static pressures are increased when total enthalpy is decreased. For reacting flow, the flame is occurred near the cavity. The combustion is weak locally in the middle of the duct. The up and down pressure distribution in the duct means that the supersonic combustion is generated.

• Journal of electromagnetic engineering and science
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• 제10권2호
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• pp.67-72
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• 2010

A new type of monopole antenna whit broadband characteristics is presented in this article. To reduce the size of the antenna, its upper part is folded. By separating the current flow, the resonance in the shorter part is in the higher band; and the longer part resonates in the lower band. This gives the broadband characteristics of the antenna. Slots on the corner using an oblique line improve the impedance matching and bandwidth. The measurement results show that the bandwidth operates from 0.848~0.992 GHz and 1.744~2.528 GHz, and the radiation patterns are in an omni-directional shape.