• 대한의용생체공학회:의공학회지
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• 제10권2호
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• pp.139-150
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• 1989

새로운 형태의 인공심장용 전동기구동형 혈액동기구동행 혈액 펌프플 개발하였다. 개발된 혈액 펌프는 소형, 고출력, 브러쉬 없는 직류 전동기를 에너지 변환 장치로 사용하였으며, 이 전동기 자체가 원호 형태의 궤적을 따라 좌우로 회전하도록 고안되었으며, 전동기를 포함한 '회전원통'의 웅직임이 좌우에 부착되어 있는 폴리우레탄으로 제작된 혈액 주머니를 번갈아 밀게 되어 혈액을 박출하게 된다. 본 연구에서 도입한 이동형 작동기 원리에 의해 다른 전동기 구동형 혈액 펌프가 안고 있는 두가지의 중요한 문제점인 펌프 크기의 증가와 자연 심장과의 해부학적인 구조상 접합의 문제점들을 개선할 수 있었다. 또한 펌프의 효율과 전동기에 의한 시스템의 온도 상승, 그러고 펌프 내에 유입되는 유체에 대한 이론적 해석을 실시하였으며, 일련의 모의 순환 실험을 통해 실험 결과를 비교하였다. 개발된 펌프 시스템은 이식형 완전 인공 심장으로 사용하기에 충분한 심박출량(9 L/m)과 전부하에 민감한 반응, 그리고 기계적인 안정도를 보여 주었다.

• 해양환경안전학회지
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• 제21권4호
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• pp.372-380
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• 2015

인공용승구조물 설치 전 후 주변해역의 하계 물리환경특성을 조사하였다. 구조물 설치 전(2002년)의 수온구조는 수심 30m에 강한 성층이 형성되었다. 한편 구조물 설치 3~4년 후(2012, 2013년)의 수온구조는 조류방향에 따라 구조물에 의한 성층의 형성수심 및 세기가 변화하였다. 이와 같은 현상은 구조물에 의한 연직류의 효과로 하계 강한 성층에 의해 저층에 분포하는 저수온수가 상승류에 의해 부상하여 성층분포에 영향을 미친 것으로 판단한다. 또한 구조물 설치 이후 연직류의 분포를 보면, 구조물 중심으로 국지적인 상승류 및 하강류가 혼재하여 나타났다. 즉 연직류는 조류방향에 따라 시 공간적인 변화를 보이면서 흐름이 진행하는 방향의 구조물 후면부에서 형성하는 상승류에 의해 성층이 약화되는 현상을 볼 수 있다. 또한 구조물에 의해 발생하는 연직류는 보다 넓은 해역으로 확장하여 발생한다. 본 연구해역에 설치한 인공용승구조물에 의해 발생하는 국지적인 용승은 한국 남동해안에 나타나는 연안 용승에 비해 유량이 100배 이상 크게 나타났다. 이와 같이 구조물에 의해 발생하는 상승류는 하계 저층에 존재하는 고농도의 영양염을 표층으로 상승시켜 주변해역의 기초생산량을 증가 시키는 역할을 가능하게 한다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권1호
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• pp.212-225
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• 2015

In order to preserve the quality of fresh water in the artificial lake after the reclamation of an intertidal flat at the mouth of a river, we suggest two novel methods of water purification by using tidal potential energy and an enclosed permeable embankment called an utsuro (Akai et al., 1990) in the reclaimed region. One method uses an inflatable bag on the seabed within an utsuro, while the other uses a moored floating barge out of a dyke. Each case employs a subsea pipe to allow flow between the inside and outside of the utsuro. The change in water level in the utsuro, which is pushed through the pipe by the potential energy outside, caused circulation in the artificial lake. In this paper, we analyzed the inflatable bag and floating barge motion as well as the pipe flow characteristics and drafts as given by a harmonic sea level, and compared the theoretical value with an experimental value with a simple small model basin. The numerical calculation based on theory showed good agreement with experimental values.

• Journal of Information Technology Applications and Management
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• 제28권3호
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• pp.109-125
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• 2021

For the government of president Moon's AI SW HRD policy, he proclaimed AI democracy that anyone can utilize artificial intelligence technology to spread AI education for the people of the country. Through cognitive map analysis, this study presents expected policy outcomes due to the input of policy factors to overcome crisis factors and utilize opportunity factors. According to the cognitive guidance analysis, first, the opportunity factor is recognized as accelerating the digital transformation to Covid 19 if AI SW HRD is well nurtured. Second, the crisis factor refers to the rapid paradigm shift caused by the intelligence information society, resulting in job losses in the manufacturing sector and deepening imbalance in manpower supply and demand, especially in the artificial intelligence sector. Third, the comprehensive cognitive map shows a circular process for creating an AI SW ecosystem in response to threats caused by untact caused by Corona and a circular process for securing AI talent in response to threats caused by deepening imbalance in manpower supply and demand in the AI sector. Fourth, in order to accelerate the digital circulation that has been accelerated by Corona, we found a circular process to succeed in the Korean version of digital new deal by strengthening national and corporate competitiveness through AI-utilized capacity and industrial and regional AI education. Finally, the AI utilization empowerment strengthening rotation process is the most dominant of the four mechanisms, and we also found a relatively controllable feedback loop to obtain policy outputs.

• 한국환경과학회지
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• 제19권9호
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• pp.1103-1108
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• 2010

This study was conducted to be used as basic data of environmental friendly construction planning by comparing and analyzing thermal environment, find particles and biotope area rate according to land cover types of outside space of schools located in Chung-ju. When meteorological factors were analyzed according to land cover types, for temperature planting area and paved area showed low-and high-temperature ranges, respectively, and relative humidity was negatively related with temperature as low-and high-temperature ranges corresponded to high-and low-humidity ranges, respectively. For Wet Bulb Globe Temperature Index (WBGT) by land cover types, it was observed to be artificial grass> bare land> natural grass. Find particles were different according to land cover types of playground with being bare land> artificial grass> natural grass in the order. Bare land playground, where there were artificial factors and no absorption of fine particles through stomata of leaves as a function of natural circulation, recorded the highest level of $39.8\;{\mu}g/m^3$ and the level was relatively higher compared to the levels by season in Chung-ju. Biotope area rate showed the order of M elementary school> K elementary school> C commercial high school. That was considered to be caused by the difference of land cover type of school playground accounting for a large part of a school.

• 한국지반환경공학회 논문집
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• 제17권5호
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• pp.27-36
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• 2016

저영향개발(LID) 기법은 물순환을 고려한 친환경 도시계획기법으로 개발 이전의 물수지를 회복시키려는 빗물관리 방법이다. 본 연구에서는 도시지역에 적용 가능한 LID 기법 중 4개(침투도랑, 식생수로, 도심형 인공습지, 측구형 침투도랑)를 선정하여 실제 적용될 지역에 시범 단지를 조성하였으며, 실제 강우와 인공강우를 이용한 모니터링을 통해 각 시설의 물순환 및 수질개선 효과를 평가하였다. 다양한 강우사상에서 모니터링한 결과 LID 시설의 표면적과 유역면적비, 그리고 시설용량과 유역면적비가 클수록 모든 강우사상에서 유출이 발생하지 않았다. 또한, 식생수로와 침투도랑은 모든 강우(최대 17.2mm)에서 유출이 발생하지 않았으며, 도심형 인공습지와 측구형 침투도랑에서는 유출이 발생하였는데 도심형 인공습지는 10mm 이하의 강우에서 유출 저감율이 높았으며, 측구형 침투도랑은 10mm 이하 및 이상의 강우에서 유사하게 나타났다. LID 시설의 구조와 강우사상, 선행건기일수에 따라 차이가 있으나 LID의 적용으로 물수지 개선 및 비점오염원 물질의 저감이 가능하다.

• Journal of Chest Surgery
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• 제23권4호
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• pp.617-621
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• 1990

A heart supplies blood of about 15, 000 liters to each human organ in a day. A normal function of heart valves is necessary to accomplish these enormous work of heart. The disease of heart valve develops to a narrowness of a closure, resulting in an abnormal circulation of blood. In an attempt to eliminate the affliction of heart valves, the operative method to replace with artificial heart valves has developed and saved numerous patients over past 30 years. This replacement operation has been performed since early 1960`s in Korea, but all the artificial heart valves used are imported from abroad with very high costs until recent years. New artificial heart valves have been developed in Korea Advanced Institute of Science and Technology since early 1980`s. The first developed valve was designed with a free-floating pyrolytic carbon disk that is suspended in a titanium cage. The design of the valve was tested in vitro, and in animals in 1987. The results from this study was that the eccentrically placed struts creates a major and minor orifice when the disc opens and stagnation of flow in the area of the minor orifice has led to valve thrombosis. In this work, the design of the valve was changed from a single - leaflet valve to double - leaflet one in order to resolve the problems observed in the first - year tests. Morphological and hemodynamic studies were made for the newly designed valves through the in vitro and in vivo tests. The design and partial materials of the artificial heart valve was improved comparing with first - year`s model. The disc in the valve was modified from single - leaflet to bi - leaflet, and the material of the cage was changed from titanium metal to silicon - alloyed pyrolytic carbon. A test was made for the valve in order to examine its mechanical performance and stability. Morphological and hemodynamic studies were made for the valve that had been implanted in tricuspid position of mongrel dogs. All the test animals were observed just before the deaths. A new artificial heart valve was designed and fabricated in order to resolve the problems observed in the old model. The new valve was verified to have good stability and high resistance to wear through the performance tests. The hemodynamic properties of the valve after implantation were also estimated to be good in animal tests. Therefore, the results suggest that the newly designed valve in this work has a good quality in view of the biocompatibility. However, valve thrombosis on valve leaflets and annulus were found. This morphological findings were in accordance with results of surface polishing status studies, indicating that a technique of fine polishing of the surface is necessary to develop a valve with higher quality and performance.

• 한국정밀공학회지
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• 제14권4호
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• pp.46-55
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• 1997

This paper presents the development of intelligent performance management of computer communication networks for larger-scale integrated systems and the demonstration of its efficacy using computer simula- tion. The innermost core of the performance management is based on fuzzy set theory. This fuzzy perfor- mance manager has learning ability by using principles of neuro-fuzzy model, neuralnetwork, genetic algo- rithm(GA). Two types of performance managers are described in this paper. One is the Neuro-Fuzzy Per- formance Manager(NFPM) of which learning ability is based on the conventional gradient method, and the other is GA-based Neuro-Fuzzy Performance Manager(GNFPM)with its learning ability based on a genetic algorithm. These performance managers have been evaluated via discrete event simulation of a computer network.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.2053-2054
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• 2011

Cardiopulmonary resuscitation(CPR) is performed by artificial ventilation and thoracic compression for the patient under emergent situation to maintain at least the minimum level of respiration and blood circulation for life survival. Good quality CPR requires monitoring respiration. We developed a system for continuous monitoring respirational signal while CPR, using respirational airflow sensor for CPR. Signal extraction circuit obtains pressure signal while CPR. Obtained signal would be performed analog-digital conversion and changed to airflow value by characteristic formula. Single inspiration and expiration were considered a period. Detected valid data were displayed LCD.

• 한국전산유체공학회지
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• 제16권4호
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• pp.84-91
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• 2011

Hemodialysis is essential for patients with end stage renal failure. It is important to improve the patency rate and to minimize occurrence of the stenosis. Also, the blood flow to the artificial kidney can affect the blood flow characteristics through arteriovenous graft. Thus, the delivered dose are important factors for analyzing hemodynamic characteristics during hemodialysis access. In this study, the numerical analysis was performed for the effect of the delivered dose during hemodialysis access on the blood flow through the graft. As a result, The adverse pressure gradient occurred in case of a larger delivered dose through a catheter than standard dose and the flow instability increased. Also the circulation flow appeared largely at anastomotic site of the vein when the delivered dose was exceeded about half blood flow of inlet blood flow.