• ETRI Journal
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• 제43권6호
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• pp.1024-1037
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• 2021

Mining high utility itemsets (HUIs) from transaction databases considers such factors as the unit profit and quantity of purchased items. Two-phase tree-based algorithms transform a database into compressed tree structures and generate candidate patterns through a recursive pattern-growth procedure. This procedure requires a lot of memory and time to construct conditional pattern trees. To address this issue, this study employs two compressed tree structures, namely, Utility Count Tree and String Utility Tree, to enumerate valid patterns and thus promote fast utility computation. Furthermore, the study presents an algorithm called single-phase utility computation (SPUC) that leverages these two tree structures to mine HUIs in a single phase by incorporating novel pruning strategies. Experiments conducted on both real and synthetic datasets demonstrate the superior performance of SPUC compared with IHUP, UP-Growth, and UP-Growth+algorithms.

• Journal of Microbiology and Biotechnology
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• 제13권5호
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• pp.687-691
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• 2003

Whole-cell immobilization of the hydrocarbon rich microalgae, Botryococcus braunii and B. protuberans, in alginate beads under air-lift batch cultures resulted in a significant increase in chlorophyll, carotenoid, dry weight, and 1ipid contents at stationary and resting growth phases, as compared to free cells. Photosynthetic activity in both the species, of Botryococcus was enhanced, relative to free cells, at any growth phase of cultures. Immobilization exerted a protective influence on ageing of the cultures as reflected by higher chlorophyll and dry weight contents. Entrapment also stabilized the chlorophyll and carotenoid contents even at stationary and resting phases as compared to free cells in both the species.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제16권1호
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• pp.15-29
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• 2012

In this paper we introduce 6-fold symmetry crystal growth using new phase-field models based on the modified Allen-Cahn equation. The proposed method is a hybrid method which uses both analytic and numerical solutions. We then show this method can be extended to $k$-fold case. The Wulff construction procedure is provided to understand and predict the shape of crystals. We also present a detailed mathematical proof of the validity of the Wulff construction. For computational results, we verify the accuracy and efficiency of the method for snow crystal growth.

• 한국신뢰성학회지:신뢰성응용연구
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• 제5권3호
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• pp.381-391
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• 2005

The level of reliability attained largely depends upon the investment in reliability growth programs during development phase. In order to find the relationship between reliability growth test time and BRTE(basic reliability tasks effectiveness) in a reliability improvement program that minimizes LCC in which contains the reliability growth cost, repair and replacement costs, and spare parts ordering costs in service with given service rate in management policy, the growth rate has been suggested proper LCC versus growth rate. This model employs the reliability growth projection with delayed fixes in avionic equipment based on AMSAA.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.891-892
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• 2006

To test the correlation between grain shape and growth behavior we prepared WC-TiC-Co samples with rounded (Ti, W)C grains and faceted WC grains. The growth of rounded (Ti, W)C grains was normal. In contrast, the growth of faceted WC grains was abnormal or suppressed depending on the initial size of WC particles. These observations were explained using growth theories of crystals in a liquid and were also confirmed by a simulation using their growth equations. The present results thus demonstrate that the growth behavior of carbide grains in a liquid is governed only by their shape, irrespective of the presence of another phase.

• 한국결정성장학회지
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• 제7권4호
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• pp.632-639
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• 1997

단일상으로서는 치밀한 소결이 힘든 TiC 와 $TiB_2$ 혼합조성을 상압소결하여 얻어진 TiC-$TiB_2$ 고온복합체의 소결밀도와 미세구조를 연구하였다. 소성조제의 임계첨가량은 1 wt% Fe 및 3 wt% Ni으로 최대 소결밀도는 약 95%이었다. TiC-$TiB_2$ 복합체의 미세구조에서 TiC상은 matrix로서 $TiB_2$입자성장을 저지하였고, wave 흑은 계단식 상계면의 존재는 석출된 Ni-rich phases가 소결중 액상으로 존재하다가 냉각시 고화한 것으로 TEM분석결과 확인할 수 있었다. 또한, 이들 Ni-rich phases는 matrix grain안에서 dislocation형성 요인으로 작용하고 있음이 확인되었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제3권1호
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• pp.11-14
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• 1998

A toluene-oxidizing strain of Pseudomanas mendocina KR1 containing toluene-4-mono-oxygenase (TMO) completely degrades TCE with the addition of toluene as a co-substrate in aerobic condition. In order to construct in situ bioremediation system for TCE degradation without any growth-stimulating nutrients or toxic inducer such as toluene, we used the carbon-starvation promoter of Pseudomonas putida MK1 (Kim, Y. et al., J. bacteriol., 1995). Upon entry into the stationary phase due to the deprivation of nutrients, this promoter is strongly induced without further cell growth. The TMO gene cluster (4.5 kb) was spliced downstream of the carbon starvation promoter of Pseudomonas putida MK1, already cloned in pUC19. TMO under the carbon starvation promoter was not expressed in E. coli cells either in stationary phase or exponential phase. For TMO expression in Pseudomonas strains, tmo and carbon starvation promoter region were recloned into a modified broad-host range vector pMMB67HES which was made from pMMB67HE(8.9 kb) by deletion of tac promoter and lacIq (about 1.5 kb). Indigo was produced by TMO under the carbon starvation promoter in a Pseudomonas strain of post-exponential phase on M9 (0.2% glucose and 1mM indole) or LB. 18% of TCE was degraded in 14 hours after entering the stationary phase at the initial concentration of 6.6 ${\mu}$M in liquid phase.

• 한국결정성장학회지
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• 제11권3호
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• pp.127-131
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• 2001

산화물계의 액상소결시 액상량을 변수로 하여 입자형성이 입자성장 거동에 미치는 영향을 고찰하였다. 산화물계 모델로 구형입자의 경우는 MgO$CaMgSiO_{4}$계를 선택하였으며, 각진입자의 경우는 $Al_{2}O_{3}$/ $CaAl_{2}Si_{2}O_{8}$계를 선택하였다. 구형입자인 MgO의 경우 액상량 증가에 따라 입자크기가 감소하였으나,각진입자인 $Al_{2}O_{3}$ 입자의 경우는 계면지배과정에 의해 성장하는 반면, 거친 고상/액상계면을 지닐 것으로 예상되는 구형 MgO입자의 경우는 확산지배과정에 의해 성장하였다.

• 한국진공학회지
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• 제8권3A호
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• pp.207-212
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• 1999

Undoped InP epilayers with high purity were grown by using $In/PCl_3/H_2$ chloride vapor phase epitaxy. It was found that the growth of InP homoepitaxial layer is optimized at the growth temperature of $630^{\circ}C$ and at the $PCl_3$ molar fraction of $1.2\times10^{-2}$. The carrier concentration of InP epilayer was less than $10^{14} {cm}^{-3}$ from the low temperature (11K) photoluminescence measurement. Growth behavior of undoped InP current blocking layer on reactive ion-etched (RIE) mesas has been investigated for the realization of 1.55 $\mu \textrm m$buried-heterostructure laser diode (BH LD), using chloride vapor phase epitaxy. On the base of InP homoepitaxy, InP current blocking layers were grown at the growth temperatures ranging from $620^{\circ}C$ to $640^{\circ}C$. Almost planar grown surfaces without edge overgrowth were achieved as the growth temperature increased. It implied that higher temperature enhanced the surface diffusion of the growth species on the {111} B planes and suppressed edge overgrowth.

• 열처리공학회지
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• 제31권5호
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• pp.237-243
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• 2018

In-rich InGaN epilayers were grown on (0001) sapphire substrates by radio-frequency plasma-assisted molecular beam epitaxy (RF-MBE). InGaN epilayers grown at various growth condition were observed by SEM, XRD, and RHEED. When plasma power of nitrogen increased from 290 to 350 W, surface morphology and crystal quality became worse according to more active nitrogen on the surface of InGaN at N-rich growth condition. As In composition was reduced from 89 to 71% by changing the incoming flux of In and Ga, surface morphology and crystal quality became worse. In addition, weak peaks of cubic InGaN phase was observed from InGaN layer with 71% In composition by XRD ${\Phi}$ scan measurement. When growth temperature decreased from 500 to $400^{\circ}C$, RHEED diffraction pattern was changed to be from streaky to spotty which means atomically rough surface, and spotty pattern showed cubic symmetry of InGaN clearly. XRD ${\Phi}$ scan measurement gave clear evidence that more cubic InGaN phase was formed at low growth temperature. All these results indicates that extremely low surface mobility of Ga adatom caused inferior crystal quality and cubic InGaN phase.