초음파를 이용한 능동 마이크로믹서

허필우,윤의수 한국유체기계학회 2005 한국유체기계학회 논문집 Vol.8 No.5

스케일 방지를 위한 2쌍 초음파 발신기 구동기법 연구

허필우,이양래,임의수,Heo, Pil-U,Lee, Yang-Rae,Im, Ui-Su 한국기계연구원 1998 硏究論文集 Vol.28 No.-

In the case of a boiler, scale is made in the tube by the chemical reactions of Ca and Mg ions contained in the water, and heat transfer rate is reduced because of increasement of heat resistance in the pipe of the heat flow. Thus it brings to reduce the energy efficiency and to make environmental pollution by the use of chemicals for the prevention and removement of scale. In this paper, we discussed the design of electronic generator for dual ultrasonic transmitters and analyzed the effect of scale prevention by ultrasound.

반복적인 알고리즘 방법에 의한 효과적인 양평균 검출 및 영상분할에 응용

허필우,Heo, Pil-U 한국기계연구원 1995 硏究論文集 Vol.25 No.-

In this paper, we discussed the convergence and the properties of an iterative algorithm method in order to improve a bimean clustering algorithm. This algorithm that we have discussed choose automatically an optimum threshold as a result of an iterative process, successive iterations providing increasingly cleaner extractions of the object region, The iterative approach of a proposed algorithm is seen to select an appropriate threshold for the low contrast images.

80C152를 이용한 멀티프로토콜의 구현

허필우,Heo, Pil-U 한국기계연구원 1995 硏究論文集 Vol.25 No.-

This paper deals with multi protocol based data communication system, which allows to improve the performances. The hardware and software of the data cmmunication system was implemented by using the CSMA/CD and Token bus access methods. The performance evaluation was also carried out and the results were verified to validate

후두와의 뇌압상승과 혈압의 증가가 전두엽 뇌피질과 뇌교 혈류 및 청각유발전위에 미치는 영향

허필우,정동섭,나형균,박춘근,강준기 대한신경외과학회 1996 Journal of Korean neurosurgical society Vol.25 No.7

Patients with extra~axial mass lesions of the posterior fossa frequently demonstrate signs of brainstem dysfunction These dysfunctions may be induced by the change of regional cerebral blood flow and electrophysiological statatus as well as mechanical compression and distortion of the brainstem frontal cortical regional cerebral blood flow (rCBF). pontine rCBF. brainstem auditory evoked potentials(AEPs). infratentorial intracranial pressure(infratentorial ICP)and mean arterial blood pressure(MABP) were recorded before and after expansion of an infratentorial epidural balloon in anesthetized experimental cat models After the elevation of MABP during the increased infratentorial ICP. frontal cortical and potine rCBF, AEPs were recorded every 30minutes The results suggest that the elevating the MABP to improve cerebral perfusion pressure before irreversible change occures in the brain may preserve cerebral function We conclude that if the volume of the space in the posterior fossa that is occupied by the mass can be estimated brain damage from low rCBF and brain compression due to intracranial hypertension can be prevented by the elevation of MABP before irreversible damage of the brain occures

뇌전산화 단층촬영을 이용한 41예의 뇌정위생검상 수술전 CT 소견과 조직소견의 비교분석

허필우,김문찬,강준기,송진언 대한신경외과학회 1987 Journal of Korean neurosurgical society Vol.16 No.2

CT guided stereotactic biopsies were carried out in 41 patients with tumorous CT findings during past 2 years. In 27 tumorous CT conditions impressed as glioma, meningioma, metastatic ca, chondroma, germinoma and craniopharyngioma, 16 cases were disclosed correctly in preoperative clinicalradiological diagnosis comparing with pathological diagnosis confirmed by means of stereotactic biopsy, but other 11 cases, showed the preoperative diagnostic error which pathological diagnosis were infarction, cryptical AVM, abscess, granuloma, and tumors such as lymphoma, oligodendroglioma, GBM, chordoma. Among 12 granulomatous CT lesions 3 cases showed preoperative diagnostic error, which were confirmed infarction, multiple sclerosis by pathological diagnosis. The pathological findings of 2 vascular lesions that were impressed as infarction and old hematoma were confirmed as granuloma and GBM. The error of preoperative clinical- CT diagnosis was 39% of total 41 patients. The advantage of preoperative stereotactic biopsy is to confirm the correct histological diagnosis, while it can help the patient and surgeon for the planning of further proper therapy.

마이크로믹서에의 응용을 위해 PMN-PT를 이용한 경계면과 수직방향 방사형 믹서

허필우,고광식,윤의수 대한전자공학회 2005 電子工學會論文誌-SC (System and control) Vol.42 No.1

A micromixer plays an important role in Bio-MEMS or μ-TAS. Mixing is generally generated by turbulence and interdiffusion of two fluids. Because of low Reynolds number values (Re << 2000) within microchannels, it is difficult to generate turbulence, and consequently mixing mainly depends on interdiffusion. So, channel distance is often prohibitively long to mix two different fluids properly. To reduce this mixing length, we proposed a new mixer for micromixing in which two fluids were effectively mixed by an ultrasonic wave generated by PMN-PT. The ultrasonic wave was radiated into a chamber in the cross-sectional direction into the boundary surface formed by two fluids. The two fluids were positioned one on top of the other. The mixing state was measured by observing the color of samples due to the reaction of NaOH and phenolphthalein. 마이크로믹서는 Bio-MEMS 혹은 μ-TAS 분야에서 중요한 역할을 수행한다. 혼합은 두 유체의 난류 상태와 상호확산에 의해 발생된다. 마이크로채널 내에서는 레이놀즈수가 작기 때문에 (Re << 2000) 난류가 발생되기 어려우므로 주로 상호확산에 의해서만 혼합된다. 따라서 두 유체가 적정하게 혼합되기 위해서는 긴 채널이 요구된다. 본 논문에서는 혼합에 소요되는 길이를 줄이기 위해서 PMN-PT에 의해 발생된 초음파에 의해 혼합되는 새로운 믹서를 제안하였다. 챔버 내에 발생된 초음파는 두 유체에 의해 생성된 경계면과 수직한 방향으로 방사된다. 사용된 두 유체는 상하방향으로 경계층을 이룬다. 혼합 상태는 NaOH와 페놀프탈렌의 반응에 따른 색상 변화를 관찰하여 측정하였다.

Cross-sectional Radiation Type Mixer into the Boundary Surface using PMN-PT for Micromixing

허필우,윤의수,고광식,Heo Pil Woo,Yoon Eui Soo,Kho Kwang Sik The Institute of Electronics and Information Engin 2005 電子工學會論文誌-SC (System and control) Vol.42 No.1

A micromixer plays an important role in Bio-MEMS or μ-TAS. Mixing is generally generated by turbulence and interdiffusion of two fluids. Because of low Reynolds number values (Re << 2000) within microchannels, it is difficult to generate turbulence, and consequently mixing mainly depends on interdiffusion. So, channel distance is often prohibitively long to mix two different fluids properly. To reduce this mixing length, we proposed a new mixer for micromixing in which two fluids were effectively mixed by an ultrasonic wave generated by PMN-PT. The ultrasonic wave was radiated into a chamber In the cross-sectional direction into the boundary surface formed by two fluids. The two fluids were positioned one on top of the other. The mixing state was measured by observing the color of samples due to the reaction of NaOH and phenolphthalein. 마이크로믹서는 Bio-MEMS 혹은 μ-TAS 분야에서 중요한 역할을 수행한다. 혼합은 두 유체의 난류 상태와 상호확산에 의해 발생된다. 마이크로채널 내에서는 레이놀즈수가 작기 때문에 (Re << 2000) 난류가 발생되기 어려우므로 주로 상호확산에 의해서만 혼합된다. 따라서 두 유체가 적정하게 혼합되기 위해서는 긴 채널이 요구된다. 본 논문에서는 혼합에 소요되는 길이를 줄이기 위해서 PMN-PT에 의해 발생된 초음파에 의해 혼합되는 새로운 믹서를 제안하였다. 챔버 내에 발생된 초음파는 두 유체에 의해 생성된 경계면과 수직한 방향으로 방사된다. 사용된 두 유체는 상하방향으로 경계층을 이룬다. 혼합 상태는 NaOH와 페놀프탈렌의 반응에 따른 색상 변화론 관찰하여 측정하였다.

고혈압성 피각출혈 환자에서 신경학적 상태의 변화에 따른 치료의 결과 분석

허필우,박영섭,정동섭,이길송,최승진,박춘근,이상원,최창락 대한신경외과학회 1996 Journal of Korean neurosurgical society Vol.25 No.2

One hundred and twenty four patients with hypertensive putaminal hemorrhage were analyzed by time course. All patients were brought to the emergency room within 3 hours after the ictus. Seventy three patients were conservatively treated and 51 patients operatively. The neurologic condition of each patient was evaluated by means of the Glasgow coma scale(GCS) score every 1 hour. CT scan of the brain of these patients were taken within 6 hours after the ictus. Clinical severity of the putaminal hemorrhage was graded as rapid deterioration, slow deterioration, and non deterioration by the CT and neurological status. A precise time course analysis of putaminal hemorrhage were compared with the conservative group and surgical group in a 7 hospital day period. Outcome was assessed 6 months later based on the degree of functional recovery(DOFR). The overall mortality was 16.1% and surgical mortality was 13.7%. Surgical treatment for the rapidly deteriorating patients appears to be beneficial when compared with the slowly deteriorating patients. Outcome of the non deteriorating patients didn't show any differences in the quality of life regardless of treatment modality.

노출형 중공사막을 이용한 압력강하에 따른 용존기체량 분리특성

허필우 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.10