• Journal of Plant Biology
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• 제38권3호
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• pp.227-234
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• 1995

Exogenous putrescine of 0.5 mM or higher concentratons applied during a 16 h inductive dark period could elevate putrescine content in cotyledons of Pharbitis nil Choisy cv. Violet, a short-day plant, resulting in complete blocking of photoperiodic floral induction. Titers of putrescine, spermidine and spermine in the cotyledons were traced throughout a 16 h dark period. While non-induced cotyledons under continous light slightly increased levels of polyamines, induced tissue maintaiend its putrescine, spermidine and spermine levels as low as 66.4%, 60.9% and 84.9% of non-induced levels respecitvely. Endogenous polyamines kept at lower levels in the inductive dark period were found to upsurge by a night break treatment of 10 min light in the middle of the dark and consequently the inductive dark effect was canceled. Elevation of polyamine titers could also be induced by 100 $\mu$L/L ethylene treatment which completely suppressed floral induction. Compared to untreated cotyledons, ehtylene-treated tissues increased putrescine content by as much as 136.5% in 12 h and spermidine level by up to 130.1% in 8 h. Ethylene-treated cotyledons not only increased endogenous polyamine content but also liberate ethylene in the second half of the inductive dark period accumulating up to three to fourfold level supporting a hypothesis that ethylene-treated tissues are stimulated to produce ethylene which in turn accelerates polyamine biosynthesis in the tissues. It is postulated that substantially low polyamine titers in the inductive dark period would be one of the necessary factors controlling photoperiodic induction of flowering in Pharbitis nil and the inhibitory effects of night break and exogenous ethylene treatment may be atributed to their action to stimulate endogenous polyamine production.

• 대한기계학회논문집B
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• 제22권12호
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• pp.1691-1701
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• 1998

Fly ash produced in coal combustion is a fine-grained material consisting mostly of spherical, glassy, and porous particles. A study on the formation mechanism of the fly ash from coal particles in the pulverized coal power plant is investigated with a physical, morphological, and chemical characteristic analysis of fly ash collected from the Samchonpo power plant. This study may contribute to the data base of domestic fly ash, the improvement of combustion efficiency, fouling phenomena and ash collection in the electrostatic precipitator. The physical property of fly ash is determined using a particle counter for the measurement of ash size distribution. Morphological characteristic of fly ash is performed using a scanning electron micrograph. The chemical components of fly ash are determined using an inductively coupled plasma emission spectrometry(ICP). The distribution of fly ash size was bi-modal and ranged from 12 to $19{\mu}m$ in mass median diameter. Exposure conditions of flue gas temperature and duration within the combustion zone of the boiler played an important role on the morphological properties of the fly ash such as shape, particle size and chemical components. The evolution of ash formation during pulverized coal combustion has revealed three major mechanisms by large particle formation due to break-up process, gas to particle conversion and growth by coagulation and agglomeration.

• 한국분무공학회지
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• 제23권1호
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• pp.30-35
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• 2018

The objective of this study is to predict numerically the effect of intake humidification on the injected diesel fuel spray characteristics in a compression ignition engine. In this work, Wave model and Ducowicz model were applied as the break-up model and evaporation model, respectively. The amount of water vapor for the humidification was changed from 0% to 30% of injected fuel mass. The number of applied meshes was generated from 49,000 to 110,000. At the same time, the results of this work were compared in terms of spray tip penetration, SMD and equivalence ratio distributions. It was found that the cylinder temperature and cylinder pressure were decreased with increasing water vapor mass by vaporization latent heat and specific heat, however, the difference was very small. So, the spray tip penetration was not different by water vapor mass. Also, higher equivalence ratio distributions were observed with increasing water vapor mass by the improvement of fuel atomization.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1307-1313
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• 2019

Recent analysis results with realistic assumptions provide the variability of operator allowable time for the initiation of aggressive cooldown under small break loss of coolant accident or steam generator tube rupture with total failure of high pressure safety injection. We investigated how plant risk may vary depending on the variability of operators' failure probability of timely initiation of aggressive cooldown. Using a probabilistic safety assessment model of a nuclear power plant, we showed that plant risks had a linear relation with the failure probability of aggressive cooldown and could be reduced by up to 10% as aggressive cooldown is more reliably performed. For individual accident management, we found that core damage potential could be gradually reduced by up to 40.49% and 63.84% after a small break loss of coolant accident or a steam generator tube rupture, respectively. Based on the importance of timely initiation of aggressive cooldown by main control room operators within the success criteria, implications for improvement of emergency operating procedures are discussed. We recommend conducting further detailed analyses of aggressive cooldown, commensurate with its importance in reducing risks in nuclear power plants.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.915-916
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• 2007

There are many equipments for the Short Circuit Test, for example Short Circuit Generator, Induction Motor, Sequence Timer, Exciter, CLR, Back Up Breaker, Making Switch and TRV etc. Especially Back up Breaker and Making Switch are very important equipments to test the short circuit test. A role of a Back up Breaker is to break high-voltage and high-current for short circuit test and a Making Switch should be operated always same speed/time and kept electrical-mechanical characteristics to make the voltage and current of short circuit test. This study introduces to the short circuit test also to kinds, principal movements and compare them of Back up Breaker and Making Switch.

• 한국가시화정보학회지
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• 제21권2호
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• pp.45-54
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• 2023

In the present study, we propose new type of a spinning disk reactor(SDR) with high performance and very convenient structure to make a large scale equipment from lab-scale than the conventional one. A split-disk experimental equipment, based on new type of spinning disk reactor, has been developed to generate an energy to break a bulk of injected gas into smaller gas bubble. Several cases of an experimental observation make it to confirm that a bulk of injecting gas could be continuously break into smaller bubbles. It shows the feasibility to make a scale-up of SDR by using the characteristic of Taylor-Proudman column in rotating flow. A theoretical study on single phase liquid flow is given to predict a liquid induced shear stress, which make the present study to be self-containment.

• 대한치과기공학회지
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• 제34권2호
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• pp.95-103
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• 2012

Purpose: Fracture strength of all-ceramic 3-unit fixed partial dentures manufactured by CAD/CAM and copy-milling systems were evaluated. Methods: Zirconia cores were made by milling the pre-sintered zirconia block by CAD/CAM or copy milling method followed by subsequent sintering. By building-up the corresponding porcelains on the core, all-ceramic bridges were fabricated, and those were evaluated in comparison with PFM fixed partial denture. Results: During the flexural test of the 3-unit PFM bridge, the porcelain started to chip or break at 507.28(${\pm}62.82$)kgf and the metal framework did not break until the maximum load level of 800kgf which was set in the testing instrument of this study. However, among all-ceramic restoration test groups, Everest(EV) group showed a peeling off or breakage of the porcelain from 365.64(${\pm}64.96$)kgf and the core was broken at 491.77(${\pm}55.62$)kgf. Those values of Zirkonzahn(ZR) were 431.03(${\pm}58.47$)kgf and 602.74(${\pm}48.44$)kgf, respectively. The break strength of the porcelain of PFM(PM) group was significantly higher than that of EV (p<0.05) group and there was no significant difference when comparing to that of ZR (p>0.05). ZR group showed higher break strength than that of EV group however there was no significant difference (p>0.05). The break strength of cores were in the increasing order of EV < ZR < PM (p<0.05). Conclusion: We could find that even though the PM group fractured at much higher value than all-ceramic cores, the breakage values of the porcelain of PM group with crack formation or delamination, which will be regarded as clinical failure, was significantly higher than that of EV group and not significantly higher than that of ZR group at p-values of 0.05. The break strength of ZR group was higher than that of EV group at an insignificant level(p>0.05).

• Journal of East Asia Management
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• 제3권2호
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• pp.43-64
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• 2022

Exploring innovations for latecomers to catch up has been a popular concern in industry and academia. Over the last decade, more and more East Asian latecomer firms have moved beyond imitation and are delivering innovative products and services to the market. However, the semiconductor latecomers from China have limited success in catching up with more mature semiconductor firms. Our study examines how semiconductor latecomers to break through the latecomer's dilemma by innovation and achieve catch-up. We use a single-case approach for the Semiconductor Manufacturing International Corporation (SMIC) vertical development process to analysis its innovation path of catching up. The study's results showed that SMIC relied on the government's policy and funding support, and based on the strategic endurance of entrepreneurs, it persisted in technology R&D investment and independent innovation for 20 years. SMIC finally smashed the dilemma of latecomers and successfully achieved catch-up. With these findings, we believe that the path of catching up innovation for semiconductor latecomers should be equipped with independent innovation of technology, strategic leadership of entrepreneurs and support of government policies. As these factors are combined, latecomer firms' position is expected to rise and catch-up will become visible. Our study contributes to some enlightenment on the innovation path for latecomers in China and global semiconductors to achieve their catch-up.

• 디지털융복합연구
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• 제17권8호
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• pp.447-452
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• 2019

미적(美的) 욕구표현의 수단으로 현대인은 외모 치장에 많은 시간과 경제적 투자를 하고 있으며, 외모의 대부분을 차지하는 헤어미용 중 멋 내기 모발 염색을 많이 애용하지만 이에 따른 모발손상도 심각한 상태이다. 그러므로 모발손상을 최소화하면서 멋 내기를 유도할 수 있도록 산화염모제에 따른 모발 인장강도에 관한 연구를 하고자 한다. 연구결과 대조군과 8N-10N 실험군 간 최대하중, 최대 인장강도, 최대 신장률, 파단 하중, 파단 강도, 파단 신장률, 평가구간에 따른 최대 모듈러스 및 접선 계수 등은 서로 유의적인 차이를 보였다. Strain 구간에 따른 최대 모듈러스와 접선 계수인 tangential modulus는 대조군과 실험군 간 차이가 있음에도 일정하게 증가하거나 감소하는 경향이 뚜렷하게 나타나지 않았다. 따라서 본 연구는 산업체 현장에서 애용되고 있는 고명도(高明渡) 멋 내기 산화염모제 시술을 통한 모발손상과의 상관관계를 데이터로 규명함으로써 헤어미용 교육 자료로서의 활용 및 헤어디자이너의 올바른 산화염모제 선택을 위한 응용자료를 제공하고자 한다.

• 한국작물학회지
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• 제42권5호
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• pp.597-603
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• 1997

한방에서 항암제로 이용되는 바위솔의 주년재배를 모색하기 위한 일련의 시험으로서 2시간의 암기중단 처리시기[6월 20일 ; 7월 18일 ; 8월 15일 ; 무처리(자연일장)]에 따른 바위솔의 생육, 추대 및 개화에 미치는 효과를 조사하기 위하여 시험을 실시하였던 바 그 결과를 요약하면 다음과 같다. 1. 초장과 개화장은 무처리에 l하여 암기중단 처리를 가함으로서 짧아졌다고 할지라도 암기중단 처리가 늦어질수록 길어졌다. 포엽을 포함한 주당 엽수도 초장과 개화장과 유사한 반응을 보였으나 7월 18일 이전에 암기중단 처리를 가할 경우 현저히 적어지는 경향이었다. 경직경은 암기중단 처리를 가할 경우 9월 중순∼10월 중순까지 증가한 후에는 변화가 없었으나 무처리에는 10월 중순 이후부터는 시간이 경과할수록 작아지는 경향이었다. 2. 개체당 각 부위별, 지상부 및 전체 건물중은 무처리와 8월 15일에 암기중단 처리를 가할 경우 8월 15일 이후부터는 타처리에 비하여 많았으며 이는 8월까지는 엽과 포엽에 의하여, 9월 이후에는 소화중, 경중 및 근중의 증가에 기인되었다. 3. 무처리에서는 9월 중순부터 소화가 형성되기 시작한 후 10월 이후 이들이 급격히 개화하여 시작하여 10월 중순경부터 전개체가 개화하였다. 그러나 암기중단 처리가 빠를수록 소화의 형성이 지연되고 소화의 개화가 현저히 줄어들어 6월 15일부터 암기중단 처리를 가한 것은 시험 종료일인 11월 초순까지도 추대가 거의 일어나지 않아 소화가 형성되지 않았다. 4. 이러한 결과는 바위솔의 추대와 개화는 분리되어 일어난다는 것을 의미하며 따라서 암기중단 처리가 가해지는 시기를 조절함으로써 추대유제 또는 추대 후 소화의 개화유제로 인공재배되는 바위솔의 주년재배는 가능할 것으로 예측되었다.