• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1909-1914
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• 2003

Bubble growth on microheater has been experimentally investigated in this study. The experiment was performed using platinum micro heaters having dimensions of $100{\times}10{\times}0.2{\mu}m^3$ with constant heat flux. A high speed video camera was used to observe bubble growth at 250 frames per second. Microheater temperature was measured at the rate of 300Hz with a data acquisition system. When heater temperature was $139^{\circ}C$ a bubble was nucleated in the liquid FC-72. The temperature profiles and the high speed camera images were combined to explain heat transfer and bubble growth on microheater.

• 대한기계학회논문집B
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• 제28권8호
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• pp.996-1003
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• 2004

The bubble motion during nucleate boiling in a microchannel is investigated by numerically solving the equations governing conservation of mass, momentum and energy in the liquid and vapor phases. The liquid-vapor interface is tracked by a level set method which is modified to include the effects of phase change at the interface and contact angle at the wall. Also, the evaporative heat flux from the thin liquid film that forms underneath a growing bubble attached to the wall is incorporated in the analysis. Based on the numerical results, the effects of channel size, contact angle, wall superheat and waiting period on the bubble growth and heat transfer in a microchannel are quantified.

• 현장농수산연구지
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• 제19권1호
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• pp.109-117
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• 2017

아직까지 많이 알려지지 않은 마이크로버블을 사용하여 우리나라 대표 작물인 인삼재배에 적용하였다. 고년근에 적용하여 결과를 확인하기 위해서는 비용과 시간 소요가 많아 종묘삼을 활용하여 생리적 변화를 측정하고 분석하였다. 최근 뿌리 작물에 기능성이 있다는 산소수 일반 재배농가에서 사용해보았지만 그 결과가 미미하고 오히려 해를 입는 경우도 생기게 되었다. 다른 작물의 선행결과와 본 연구결과를 볼 때 마이크로 버블을 사용한 인삼재배는 파급효과 있을 것으로 사료된다. 중화제 및 약제를 활용하여 만든 산소수와는 다른 개념으로 마이크로 버블은 공급 장치를 통해 우리가 이용하는 공기를 아주 작은 버블로 압축하여 인삼에 제공함으로써 저해 없이 특이성 성장을 이끌어 내었다. 연구결과로부터 설정된 종묘삼의 생장 특성 및 세분화별 적정범위 및 적정치를 결과와 비교하면, 그동안 이루어졌던 관행농법에서 사용되는 일반수와 마이크로 버블(Micro bubble)수를 사용하여 재배한 결과는 10%에서 15%의 인삼생장을 나타내었다. 이후로 마이크로 버블수를 생산할 때 시간별 용존 산소량을 측정하여 마이크로 발생장치의 최적 시간을 설정하고 최적화 설정을 위해서는 관계시간과 에너지 효율 및 토양의 영양환경에 대한 변화에 대해서도 더욱 많은 연구가 필요하고 사료되며, 더불어 생체 및 중량이 증가된 만큼 인삼의 주요 성분인 진세노사이드의 증감에 대한 분석 등 추가 연구가 활발하게 이루어져야 할 것이다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1196-1200
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• 2004

Micropump is very useful component in micro/nano fluidics and bioMEMS applications. In this study, a bubble-powered micropump was fabricated and tested. The micropump consists of two-parallel micro line heaters, a pair of nozzle-diffuser flow controller and a 1 mm in diameter, 400 ${\mu}m$ in depth pumping chamber. The two-parallel micro line heaters with 20 ${\mu}m-width$ and 200 ${\mu}m-length$ were fabricated to be embedded in the silicon dioxide layer of a wafer which serves as a base plate for the micropump. The pumping chamber, the pair of nozzle-diffuser unit and microchannels including the liquid inlet and outlet port were fabricated by etching through another silicon wafer. A glass wafer (thickness of $525{\pm}15$ ${\mu}m$) having two holes of inlet and outlet ports of liquid serve as upper plate of the pump. Finally the silicon wafer of the base plate, the silicon wafer of pumping chamber and the glass wafer were aligned and bonded (Si-Si bonding and anodic bonding). A sequential photograph of bubble nucleation, growth and collapse was visualized by CCD camera. Clearly liquid flow through the nozzle during the period of bubble growth and slight back flow of liquid at the end of collapsing period can be seen. The mass flow rate was found to be dependent on the duty ratio and the operation frequency. As duty ratio increases, flow rate decreases gradually when the duty ratio exceeds 60%. Also as the operation frequency increases, the flow rate of the micropump decreases slightly.

• 국제초고층학회논문집
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• 제12권3호
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• pp.195-201
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• 2023

This paper reviews the history of the birth and development of the skyscraper in Japan, mainly from the perspective of the legal system, and presents the following points: 1) After 1919, building height was limited to 31 m or less, which continued after the war and defined the skyline of Japan's major cities; 2) The 31-meter height limit became a problem during rapid economic growth. With the development of tall building construction technology, the height limit was eliminated, and skyscrapers were born in Japan in the 1960s; 3) Later, the number of skyscrapers increased more rapidly in the post-bubble period after the collapse of the bubble economy in the 2000s than in the boom years of the 1980s, when the floor-area ratio was relaxed for economic uplift and urban renewal. The number of skyscrapers increased rapidly against the backdrop of the deregulation of the floor-area ratio.

• 한국융합학회논문지
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• 제8권12호
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• pp.1-7
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• 2017

본 연구는 환경정화에 주로 사용되는 미세기포를 2년 근 인삼 지속적으로 처리하여 인삼이 성장하면서 변화되는 형태와 ginsenoside 변화를 조사하는 융합적 연구이다. 인삼 재배시 미세기포수를 적용하여 4개월 동안(120일) 재배한 후 인삼의 잎과 뿌리의 부위별 ginsenoside 함량과 조성을 분석하였다. 잎에 일반수를 처리한 결과 protopanaxatriol(PPT) 계열 Re 함량만 월등히 높게 나타났지만 미세기포수를 처리한 결과 protopanaxadiol(PPD) 계열 Rb1, RC, Rb2, Rd 성분도 같이 증가시키는 것을 확인하였다. 특히 Re, Rb1이 다량 증가함으로써 전체적인 total ginsenoside가 증가하는 요인이 되었다. 인삼의 부위별 PD/PT 비율은 미세기포수를 처리한 잎에서는 0.811으로 나타나고 뿌리는 1.28로 나타났다. 이것은 미세기포수 처리가 뿌리에서 ginsenoside의 합성을 유도하여 PD/PT 비율이 1과 가까운 결가를 가져와 유용성분의 증가 및 고른 분포 이루어졌다고 판단된다. 따라서 미세버블수를 사용한 고품질 인삼을 생산하는 재배 방법을 제시하고 인삼의 뿌리와 더불어 잎도 기능성 식품 소재로 활용할 수 있는 가능성을 제시하였다.

• 한국균학회지
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• 제31권2호
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• pp.89-93
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• 2003

송이균사의 대량배양에 적합한 공기부양식 생물반응기 형태를 찾고자 풍선형 및 칼럼형의 공기부양식 생물반응기와 external-loop형의 기포통기식 생물반응기에서 송이균사체를 심부배양하여, 반응기 형태별 송이균사체의 생장특성을 비교하였고, 반응기 형태가 세포에 주는 스트레스 정도를 비교하기 위하여 배양기 형태별 균사체의 에르고스테롤의 함량 변화를 비교하였다. 반응기 형태별 송이 균사체의 생산량은 풍선형 생물반응기에서 평균 12g, external-loop형의 기포통기식 생물반응기에서 평균 11.4g, 칼럼형 생물반응기는 평균 9.5g을 생산하여, 풍선형 생물반응기가 가장 우수하였다. 생장기간도 풍선형 생물반응기에서 균사 접종 후 16일 이후부터 정체기에 이르는 것으로 20일 이후에 나타난 칼럼형 및 기포통기형 생물반응기 보다 빠르게 생장하는 것으로 나타났다. 균사체의 생장시기별 에르고스테롤의 함량은 풍선형 공기부양식 생물반응기에서 가장 높이 나타났으며 이어서 칼럼형, 기포통기식 순으로 나타나, 송이 균사체 배양시 반응기 형태에 의한 물리적 스트레스는 풍선형 공기부양식 생물반응기가 가장 적게 받는 것으로 추정되었다. 송이 균사체 배양에 가장 적합한 공기부양식 생물반응기의 형태는 풍선형인 것으로 추정 할 수 있었다. 그러나 칼럼형 및 풍선형 공기부양식 생물반응기는 스파자 부근에서 균사체가 침적, 착생하여 점차 크게 뭉쳐 성장하면서 공기공급을 차단하는 현상이 있었으나 external-loop형의 기포통기식 생물반응기에서는 유체의 순환으로 이러한 현상은 적게 나타나 대용량의 송이 균사체 배양에 적합한 반응기 형태로는 배양기의 상부가 풍선형 반응기의 형태를 유지하고, 스파자가 위치한 하부는 external-loop형의 기포통기식 생물반응기의 유체 순환식 형태를 유지하도록하는 혼합형의 형태가 좋을 것으로 추정되었다.

• 토지주택연구
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• 제2권3호
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• pp.227-238
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• 2011

There are similarities between Korea and Japan in terms of national planning and development system and housing policies. Japan has suffered from great shifts of social and economic systems due to skyrocketing land prices for three times and the collapse of the bubble economy after the Second World War. The study reviews historically important changes in the national territory and housing policies for last 60 years in Japan. It also investigates changing trends and characteristics of many socioeconomic indicators with regard to population, housing and other fields in response to these policies. First of all, Japan has experienced significant economic growth before and after the 1960's, and the era of national rebuilding projects in the 1970's. After then, the period of the bubble economy has emerged since 1980; however, it suffered from skyrocketing land values between the late 1980's and the early 1990's, and the collapse of Japanese bubble economy in the early 1990's. In response, many urban regeneration policies and projects were proposed to recover the national economy since 2000. It is found that these national territory development and housing supply policies throughout the country have been influenced by the changing characteristics of social and economic conditions. Since the housing supply ratio in 1968 reached up to around 100% on average, Japan has been focusing attention to improving the residential and living quality for existing housing stock rather than supplying new housing units through large-scale new town projects. These experiences are full of helpful suggestions for our future housing and urban regeneration policies as we reach to more than 100% of housing supply ratio on average.

• 반도체디스플레이기술학회지
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• 제17권3호
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• pp.75-84
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• 2018

According to IHS, the overall display market is expected to grow at an average annual rate of 6% from $ 104 billion in 2016, to $ 138 billion in 2021. Among them, the OLED display panel will grow from $ 15 billion to $ 41 billion over the same period, forecasting a high annual growth rate of 22%. However, the refraction index, light leakage, bubble generation, adhesion deterioration, peeling phenomenon, moisture resistance, light transmittance, low turbidity. OCA (optically clear adhesive), which solves problems such as improving the resistance of the conductive film, is largely dependent on imported products. In addition, in 2016, the world market is worth KRW4.3 trillion, and the adhesive market has a large market effect. In this study, we tried to analyze the technical competitiveness of patent and thesis by classifying OCA (optically clear adhesive, optical adhesive) for display panel by curing method. As a result of the study, the amount of patents and papers in Korea was found to be superior to other competitors, but the quality level was low. In particular, it was found that the achievements of the papers in the hot melt field are lacking and the government should expand its support.

• Journal of Plant Biotechnology
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• 제5권1호
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• pp.1-6
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• 2003

The adventitious root of Panax ginseng C.A. Meyer is regarded as an efficient alternative to cell culture or hairy root culture for biomass production due to its fast growth and stable metabolite production. To determine optimal culture conditions for the bioreactor culture of ginseng roots, experiments have been conducted on physical and chemical factors such as bioreactor type, dissolved oxygen, gas supply, aeration, medium type, macro- and micro-elements, medium supplement during culture period, sucrose concentration, osmotic agents, medium pH and light. Elicitation is a key step to increase ginsenoside accumulation in the adventitious roots but biomass growth is severely inhibited by elicitor treatment. To obtain high ginsenoside content with avoiding biomass decrease, we applied two-stage bioreactor culture system. Ginseng adventitious roots were cultured for 40 days to maximize biomass increase followed by elicitation for 7 days to enhance ginsenoside accumulation. We also experimented on types and concentrations of jasmonate to determine optimal elicitation methods. In this paper, we discussed several factors affecting the root propagation and ginsenoside accumulation. Based on the results obtained from previous experiments we have established large-scale bioreactor system (1 ton-10 ton) for the efficient production of ginseng adventitious roots and bioactive compounds including ginsenoside. Still, experiments are on going in our laboratory to determine other bioactive compounds having effects on diet, high blood pressure, DPPH elimination and increasing memories.