• 한국임상수의학회지
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• 제37권6호
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• pp.355-359
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• 2020

Contrast-enhanced ultrasonography (CEUS) has been applied to evaluate parenchymal organs in human and veterinary medicine. However, to our knowledge, there is no report on the identification of active bleeding and the bleeding site in veterinary clinical patients. Herein, we describe the use of CEUS in two cases of abdominal bleeding caused by ruptured lesions with malignant abdominal tumors. One dog had a splenic hemangiosarcoma, which had metastasized to the liver; the other dog had hepatic cell carcinomas in the left hepatic lobe, which were lobectomized, and another nodule was identified in the right hepatic lobe. Immediately after the rupture of these oncogenic lesions was suspected, CEUS was performed to identify the bleeding sites. The active bleeding sites were confirmed by hyperechoic pooling signs in the arterial phase, and extravasation could be observed within the defects showing hypoechoic perfusions in the delayed phase of the CEUS. Microbubbles were also observed in the ascites; thus, CEUS could detect the presence of hemorrhage and accurately identify the bleeding site. Collectively, the study findings suggest the usefulness of CEUS in emergent situations as it enables rapid and noninvasive evaluation of bleeding points in case of active bleeding in dogs.

• Nuclear Engineering and Technology
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• 제53권1호
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• pp.79-92
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• 2021

Venturi tube is based on turbulent flow, whereby the microbubbles can be generated by the turbulent fragmentation. This phenomenon is common in several venturi bubblers used by the nuclear, aerospace and chemical industries. The first objective of this paper is to study the liquid-phase velocity field experimentally and develop correlations for the turbulent quantities. The second objective is to research velocity field characteristics theoretically. Stereoscopic PIV measurements for the velocity field have been analyzed and utilized to develop the turbulent kinetic energy in the venturi tube. The tracking properties of the tracer particles have been verified enough for us to analyze the turbulence field. The turbulence kinetic energy has a bimodal distribution trend. Also, the results of turbulence intensity along the horizontal direction is gradually uniform along the downstream. Both the mean velocity and the fluctuation velocity are proportional to the Reynolds number. Besides, the distribution trend of the mean velocity and the velocity fluctuation can be determined by the geometric parameters of the venturi tube. An analytical function model for the flow field has been developed to obtain the approximate analytical solutions. Good agreement is observed between the model predictions and experimental data.

• 열처리공학회지
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• 제35권1호
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• pp.27-32
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• 2022

Microbubble technology has been widely applied in various industrial fields. Recently, research on many types of microbubble application technology has been conducted experimentally, but there is a limit in deriving the optimal design and operating conditions. Therefore, if the computational fluid dynamics (CFD) analysis of multiphase flow is used to supplement these experimental studies, it is expected that the time and cost required for prototype production and evaluation tests will be minimized and optimal results will be derived. However, few studies have been conducted on multiphase flow CFD analysis to interpret fluid flow in microbubble generators using swirl flow. In this study, CFD simulation of multiphase flow was performed to analyze the air-water mixing process and fluid flow characteristics in a microbubble generator with a dual-chamber structure. Based on the simulation results, it was confirmed that a negative pressure was formed on the central axis of rotation due to the strong swirling flow. And it could be seen that the air inside the suction tube was introduced into the inner chamber of the microbubble generator. In addition, as the high-speed mixed fluid collided with external water sucked by the negative pressure near the outlet, a large amount of microbubbles was ejected due to the shear force between the two flows flowing in opposite directions.

• 대한환경공학회지
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• 제36권3호
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• pp.172-177
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• 2014

가압형 부상법에 비해 낮은 압력에서 미세기포를 발생시키는 저압형 부상법을 슬러지 부상 농축에 적용하여 그 성능을 검증하고 실제 적용가능성을 확인하였다. 파일롯 규모의 저압형 부상조를 충남 N.S. 하수처리장에 설치하여 혼합슬러지의 농도, 응집제 주입량 및 혼합슬러지 대비 미세기포수의 비율과 같은 운전 변수가 혼합슬러지 농축에 미치는 영향을 확인하였다. 미세기포는 내부 압력이$1.5kgf/cm^2$으로 유지된 미세기포발생기에서 공기와 기포조제가 포함된 물을 고속 충돌 방식으로 발생시켰으며, 이를 부상농축 실험에 사용하였다. 장기운전 시 유입된 혼합슬러지의 SS 농도는 평균 14,400 mg/L였으며, 응집제 농도 27.6 mg/L, 기포조제 농도 4.0 mg/L, 혼합슬러지 대비 미세기포수의 비를 9.7%로 하여 저압형 부유부상조를 운전한 결과, 60,300 mg/L의 농축슬러지 고형물함량과 99% 이상의 고형물 회수율을 얻었다. 이 경우의 고형물 표면적 부하율은 $30kg/m^2/hr$로 2011년 환경부에서 제정한 하수도 상압 부상농축 시설기준 25 $kg/m^2/hr$을 상회하였다.

• 한국물환경학회지
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• 제21권5호
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• pp.528-534
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• 2005

Ozone, a powerful oxidant, is widely used to remove microorganisms, pesticides, taste and odor compounds effectively. Dissolved air flotation (OAF) has been known as an economical process for treating algae and low turbid water quality. An ozoflotation system, combining ozone and OAF processes, has a merit which can operate the ozonation and flotation process simultaneously in a single compartment. This study investigated the application of the ozoflotation process for advanced water treatment by carrying out the pilot-plant experiment. During the test, ozone microbubbles were generated through a OAF pump and many kinds of parameters were evaluated under several conditions, such as raw water flow rate and ozone dose. As a result of the test, the optimum operating conditions of ozoflotation were decided to be 1.2 mg/L ozone dose and about 34 minute Hydraulic retention time (HRT). Finally, it could be demonstrated that the ozoflotation system can effectively improve the drinking water quality.

• 한국환경복원기술학회지
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• 제21권5호
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• pp.17-28
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• 2018

Cyclonic-dissolved air flotation(Cyclonic-DAF), an advanced form of pressure flotation, applies a structure that enables the forming of twirling flows. This in turn allows for suspended matter to adhere to microbubbles and float to the surface of a treatment tank during the process of intake water flowing through a float separation tank. This study conducted a lab-scale test and pursued geometrical modeling using computational fluid dynamics(CFD) to establish a pilot scale design. Based on the design parameters found through the above process, a pilot cyclonic-DAF system($10m^3/hr$) for removing algae was created. Upon developing the pilot-scale cyclonic-DAF system, a type of algae coagulant(R-119) was applied as the coagulant to the system for field testing through which the removal rates of chlorophyll-a and cyanobacteria were evaluated. The chlorophyll-a and harmful cyanobacteria of the raw water at region B, the field-test site, were found to be $177.9mg/m^3$ and 652,500cells/mL respectively. Treated waters applied with 60mg/L and 100mg/L of algae coagulant presented removal efficiencies of approximately 95% and 97%, respectively. The cyanobacteria cell number of the treated waters applied with 60mg/L and 100mg/L of algae coagulant both that were equal to or less than 1,000cells/mL and were below attention level criteria for the issuance of algae boundary.

• Tuberculosis and Respiratory Diseases
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• 제66권1호
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• pp.47-51
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• 2009

간폐증후군은 간질환이 있는 환자에서 저산소증이 유발되는 상태로 폐내 혈관 확장으로 인해 폐내 동맥혈 산소공급에 결함이 발생하는 질환이다. 현재까지 간이식 외에 간폐증후군에 대한 다른 효과적인 치료법은 없는 것으로 알려져 있다. 국내에서는 간폐증후군의 증례 보고가 드물고, 특히 Child-Pugh 분류 A군에서의 발생 빈도는 낮은 것으로 보인다. 이에 저자들은 Child-Pugh 분류 A군인 대상성 간경화 환자에서 발생한 간폐증후군 1예를 경험하여 문헌 고찰과 함께 보고하는 바이다.

• 대한의용생체공학회:의공학회지
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• 제40권6호
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• pp.250-259
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• 2019

Ophthalmic Laser System is widely used in Selective Laser Trabeculoplasty of Open Angle Glaucoma and Ocular Hypertension. Versatile ophthalmic laser system is a medical device with technology that checks the condition of the treatment area by irradiating a continuous laser pulse on the treatment area, and monitoring the microbubble reaction caused by the temperature increase of the melanosome through the ultrasonic signal and the optical signal sensor. It performs selective laser treatment without damaging the photoreceptor by controlling the wavelength of the laser when microbubbles are detected. This study aims to suggest a guideline for evaluating safety, performance and clinical effectiveness of Versatile Ophthalmic Laser System in accordance with the growing technology. International Standards, Regulations, and Clinical Trial Protocols were investigated and analyzed for this study. As a result of this study, the safety, performance and clinical effectiveness test guideline for Versatile Ophthalmic Laser System were proposed. This guideline will ensure the safety and efficacy of Medical device, and furthermore it is expected to be able to promote the development of technology development by supporting a clinical trial plan.

• 한국물환경학회지
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• 제37권1호
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• pp.10-19
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• 2021

In the flotation process to remove microplastic (MP) particles, the attachment and separation efficiency is determined by the basic physicochemical characteristics of MP particles as well as bubbles. To evaluate the flotation characteristics of MP particles, we carried out a series of simulations using the population balance (PB) model. The initial attachment coefficient (αo) of MP particles was in the range of 0.2-0.275, and it was slightly lower than that of typical particles, such as clay, debris and algae particles, which exist in water bodies, αo, 0.3-0.4. The relative bubble number (RBN) attached to the surface of the typical number of bubbles was 0.30 and 0.32 for MP 30 ㎛ and MP 58 ㎛, respectively. In comparison, the RBN of larger MP particles (138 ㎛) was as high as 0.53. Furthermore, smaller microbubbles were required to separate properly or additional treatment needed to be applied to enhance collision and attachment efficiency since the flotation of MP particles was found to be difficult to treat as high-rate. As a result of comparing the removal rate (experimental value) of MP particles obtained from the batch-type flotation apparatus and the flotation removal rate (predicted value) of MP obtained through the PB model, the final particles by the particle size of MP overall except for the initial separation time area. With respect to the removal efficiency, the observed and predicted values were similar, and it was confirmed that the floating separation characteristics and evaluation of the MP particles through the PB model could be possible.

• 한국음향학회지
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• 제41권5호
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• pp.564-569
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• 2022

인체의 다른 장기들과 달리, 뇌는 혈뇌장벽(Blood-Brain Barrier, BBB)라는 보호 장치가 존재하여 뇌혈관내 물질들이 뇌조직으로 투과되는 것을 제한하는 역할을 한다. 이러한 BBB는 알츠하이머, 뇌종양 등 다양한 뇌질환에 직접적으로 전달이 필요한 약물의 투과까지 제한하기 때문에 치료 효능 검증 및 임상 적용이 어려운 것으로 보고되고 있다. 이러한 문제를 극복하기 위해 비침습적 특성의 집속 초음파(Focused Ultrasound, FUS)를 뇌의 국소 부위에 조사할 경우 마이크로버블의 음향공동화 현상으로 인해 BBB가 일시적으로 개방될 수 있는 기술이 개발되었으며, 해당 기술을 안전성 및 유효성 검증, 약물 전달 효율을 증대시킬 수 있는 다양한 연구가 전 세계적으로 수행되고 있다. 따라서, 본 논문에서는 알츠하이머, 뇌종양 등 뇌질환 치료를 위해 활발히 연구가 진행중인 집속초음파 기반 BBB 개방 기술에 대한 연구 동향을 분석하였다.