Separation characteristics of prepared exhalation gases scattered in water using hollow fibers

허필우 한국마린엔지니어링학회 2023 한국마린엔지니어링학회지 Vol.47 No.6

Underwater breathing requires a large amount of oxygen. As water contains limited dissolved oxygen, devices must be sufficiently large to obtain the required oxygen. Exhaled breath, which contains a large amount of oxygen, can be reused to make devices compact and portable. In this work, gases with the characteristics of exhaled breath were mixed with water using a hollow fiber membrane. The gases were mixed with water in the form of small bubbles, which increased the contact area between the gases and water. The mixed state was visualized by increasing the amount of prepared gases. Dissolved gases were separated from water con-taining the prepared gases. The amount of separated gases increased with the amounts of prepared gases and water. The separated dissolved gases could be used for underwater respiration.

마이크로믹서에의 응용을 위한 batch type 초음파믹서의 혼합상태 가시화

허필우,윤의수,고광식 한국센서학회 2005 센서학회지 Vol.14 No.2

An active μ-mixer is important in Bio-MEMS and μ-TAS. The mixing state depends on some kinds of factors including the intensity of ultrasonic radiation. We have visualized the mixing state of the mixing chamber with radiation time and presented the influence of the driving voltage in this research. It will be possible to compare the performances of the ultrasonic radiation parts used in the active μ-mixer using this method.

연구소기업 설립 적합유형 및 핵심요인에 관한 연구: 연구소기업 대표자를 대상으로

허필우,천동필 한국경영교육학회 2018 경영교육연구 Vol.33 No.4

[Purpose] The government has operated Special R&D Zones to create new technology through R&D and to promote commercialization of the R&D results. Research Institute Companies in Special R&D zones, which get various policy benefits, act as emerging role of innovative body to the regional innovation. However, systematic studies have not been done on the types of Research Institute Company yet and most of the studies on innovative bodies focus on Daejeon and the capital area. In this study, we analyzed the suitable types for Research Institute Company and important factors on deciding the types of Research Institute Company. [Methodology] This study was conducted on the representatives of the Research Institute Companies in the Busan Special R&D Zone, using the AHP(Analytic Hierarchy Process) to analyze the preference regarding the type of Research Institute Company in the demanders’ perspective. [Findings] It was found that, when decide the type of Reseach Institute Company, the most important factor was the technical factor; the technical superiority was selected as the element with highest priority. Meanwhie, Joint Venture Type was the most preferred among the three types of Research Institute Company. [Implications] This study has established a system to decide the suitable type of the Research institute Company and obtained implications for policy. [연구목적] 정부는 연구개발을 통한 성과 창출 및 연구개발성과의 확산을 위하여 연구개발특구 제도를 시행하고 있다. 연구개발특구 내 다양한 정책 지원을 수혜 받고 있는 연구소기업은 지역혁신활성화를 위해 새롭게 등장한 혁신 주체이다. 그러나 이러한 연구소기업 설립 유형에 대한 연구는 체계적으로 이루어지지 않고 있으며, 대부분의 혁신주체 관련 연구는 수도권과 대전 중심으로 이루어지고 있다. 본 연구는 설문을 통하여 연구소기업 적합유형과 유형선정에 영향을 미치는 중요한 요소를 분석하였다. [연구방법] 본 연구는 부산시 소재 연구소기업 대표자를 대상으로 AHP(Analytic hierarchy process, 계층적 분석기법)를 실시하여 수요자 관점에서 연구소기업 설립 유형선호도에 관한 연구를 수행하였다. [연구결과] 연구소기업 유형을 선정하는 데 가장 중요한 요인은 기술요인으로 나타났으며, 그 중 기술의 우수성이 최우선적으로 고려할 요소로 선택되었다. 또한, 세 가지 연구소기업 유형 중, 합작투자형을 가장 선호하는 것으로 나타났다. [연구의 시사점] 본 연구는 새로운 혁신 주체인 연구소기업의 적합유형을 선정하는 시스템을 확립하고 정책적 시사점을 도출하는 성과를 거두었으며, 특히 이미 설립된 연구소기업의 대표자를 대상으로 연구를 진행하였다는 데에 큰 의의가 있다.

초음파 스케일 방지를 위한 전자구동기법에 관한 연구

허필우,이양래,김재형,임의수,Heo, Pil-U,Lee, Yang-Rae,Kim, Jae-Hyeong,Im, Ui-Su 한국기계연구원 1996 硏究論文集 Vol.26 No.-

In the case of a heat exchanger, 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 increment 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 ultrasonic scale preventor and analyzed the fundamental characteristic for ultrasonic transducer.

실험적 뇌수종시 뇌실확장에 대한 체성감각 유발전위 변화

허필우,조병일,이재수,조경석,정철구,박춘근,백민우,김문찬,김달수,강준기,최창락 대한신경외과학회 1990 Journal of Korean neurosurgical society Vol.19 No.2

We investigated the somatosensory evoked potentials(SEPs) changes and subsequent changes of the ventricular enlargement in different stages of kaolin-induced hydrocephalus. 8 week-old fifty five cats weighing 900g to 1300g, were studied in this experiment. These animals were divided into 2 groups ; a normal control(5 cats), kaolin-induced hydrocephalic groups(50 cats). The kaolin-induced hydrocephalic groups was subdivided into 5 subgroups of 10 cats each ; kaolin induced 1,2,4,6 and 8 weeks hydrocephalic groups after an intracisternal injection of the kaolin. At the each stage of the kaolin-induced hydrocephlalic animals, the following parameters were obtained : somatosensory evoked potentials(SEPs) and the size of enlargement of the ventricles at the each stage of 1, 2, 4, 6 and 8 weeks after intracisternal kaolin injection. The results were as follows : 1) A significant elevation of the intracranial pressure(ICP) was observed in 2 weeks after kaolin injection and peak valus(ICP : 10.2±0.9 ㎜Hg) in 4 weeks after kaolin injection. 2) The mean latencies of these wave components in somatosensory evoked potentials(SEPs) responses were 6.27±0.12 msec in Po, 8.41±0.25 msec in No, and 12.55±0.36 msec in P₁and he mean central conduction time(P₁-Po) was 6.10±0.16 msec in the normal control animals. 3) Changes of amplitude and latency in SEPs were more porminent in 4 weeks after kaolin injection and progressively prolonged latencies of each wave components and CCT were resulted in 6 and 8 weeks after kaolin injection. 4) In hydrocephalic animals, the size of the ventricle(septum pellucidum(SP)-caudate nucleus(CN) distance) was moderately increased to 5.19±0.43 ㎜ in 1 week after kaolin injection and continued to increase in maximum size up in the 4th week after injection. However there was no further increase in ventricular size after 4th weeks. 5) A close correlation was found between SEPs and ventricular enlargement at the each stage of kaolin-induced hydrocephalic animals. In conclusion, it is assumed that the detection of SEPs in hydrocephalus is a quite valuable prognostic tool to evaluate the functional integrity of the nerve conduction system near the paraventricular area which might be involved ventricular enlargement.

흉추와 척추강내에 침범된 악성 흉선종 : 증례보고 Case Report

허필우,김명식,조경근,조경석,백민우,송진언,장은덕,지영희 대한신경외과학회 1987 Journal of Korean neurosurgical society Vol.16 No.2

Most thymomas are found in the superior and anterior mediastinum and malignant thymomas are exceedingly rare in the first 20 years of life. A child of malignant thymoma with invasion into the thoracic vertebra and spinal canal is reported. The tumor was originated from posterior mediastinum and involved posteriorly the D8, D9 vertebra resulting in paraparesis by its presenting symptoms. After surgical removal of spinal canal mass, the paraparesis was improved. Computed tomography is mandatory in detecting the metastasis and evaluation of treatment.

노출형 중공사막을 이용한 압력강하에 따른 용존기체량 분리특성

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

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.

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.

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.