• 설비공학논문집
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• 제8권1호
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• pp.151-165
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• 1996

Relation between condensate retention and heat transfer performance is studied for condensation of CFC-11 on horizontal integral-fin tubes. Eight tubes with trapezoidally shaped integral fin density from 738fpm to 1654fpm and 10, 30 grooves are tested. The liquid retention angles are measured by the height gauge, and each tube is tested under static(non-condensing) condition (CFC-11, water) and under dynamic(condensing) condition (CFC-11). The analytical model predicts the amount of liquid retention on a horizontal integral-fin tubes within＋10 percent over most of the data. Average retention angle increases as both surface tension-to-density ratio($\sigma/\rho$) and fin density(fpm) increase, The tube having a fin density of 1299~1654fpm has the best heat transfer performance. The amount of surface flooding must keep below of 40 percent for best heat transfer performance at condensation. The tube having low number of fin density must be used for fluids having high values of $\sigma/\rho$(water, (TEX)$NH_3$, ect.) and the tube having high number of fin density must be used for the fluid having low values of $\sigma/\rho$(R-11, R-22, etc.)

• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3587-3591
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• 2011

The reactions of O,O-diethyl Z-S-aryl phosphorothioates with X-benzylamines are kinetically investigated in dimethyl sulfoxide at $85.0^{\circ}C$. The Hammett (log $k_2$ vs ${\sigma}x$) and Br$\ddot{o}$nsted [log $k_2$ vs $pK_a$(X)] plots are biphasic concave downwards for substituent X variations in the nucleophiles with a break point at X = H. The signs of the cross-interaction constants (${\rho}xz$) are positive for both the strongly and weakly basic nucleophiles. Considerably great magnitude of ${\rho}xz$ (= 6.56) value is observed with the weakly basic nucleophiles, while ${\rho}xz$ = 0.91 with the strongly basic nucleophiles. Proposed reaction mechanism is a stepwise process with a rate-limiting leaving group expulsion from the intermediate involving a backside nucleophilic attack with the strongly basic nucleophiles and a frontside attack with the weakly basic nucleophiles. The kinetic results are compared with those of the benzylaminolysis of O,O-diphenyl Z-S-aryl phosphorothioates.

• 전자공학회논문지B
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• 제32B권11호
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• pp.1473-1480
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• 1995

When the LMS algorithm is employed in the transversal filter structure, the computational complexity can be kept reasonably low. However, if the impulse response to be estimated is very long or signals involved are highly correlated like a speech the convergence speed becomes slow. The lattice filter is an excellent alternative to improve convergence speed since the lattice structure inherently has the orthogonal property among the backward prediction errors, but at the expense of the excessive computational load. If the input signal to be used can be sufficiently well modeled as a .RHO.-th order autoregressive(AR) process, the reflection coefficients after the .RHO.- th stage will be close to zero. Then, instead of employing the full lattice structure, the joint lattice filter structure can be implemented in conjunction with the transversal filter structure after the .RHO.-th stage. We propose, in this paper, this new lattice/transversal joint structure, and we will call it the reduced lattice filter. Using the reduced lattice filter, we are now able to achieve the performance as good as that of the lattice filter, while maintaining the complexity as low as that of the transversal filter. The proposed filter is particularly useful for an acoustic echo canceller due to the highly correlatedness nature of speeches and the long and frequently changing echo paths.

• 대한화학회지
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• 제33권1호
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• pp.120-126
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• 1989

pH 0.0∼14.00 범위에서 styrylphenylsulfone 유도체들의 가수분해반응에 대한 반응속도론적 연구가 25$^{\circ}$C의 50% 메탄올-물속에서 자외선 분광법으로 이루어졌다. 반응속도식과 치환기 효과(${\rho}$=1.85(pH 7.0), ${\rho}$=1(pH 13.0))로부터, pH 11.0이상에서는 전형적인 Michael형의 친핵성 첨가반응, pH 9.0이하에서는 물분자에 의한 일반 염기촉매반응, 그리고 pH 9.0∼11.0사이에서는 이들 두 반응이 경쟁적으로 일어남을 제안하였다.

• KSBB Journal
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• 제18권1호
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• pp.74-77
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• 2003

대표적인 부패산물들로 잘 알려진 indole, skatole, 그리고 $\rho$-cresol 등을 측정하기 위한 방법으로 HPLC, spectrophotometric 법, 그리고 GC 및 GC/MSD 방법 등이 있으며, 수십년 간에 걸쳐 이러한 물질들의 분석이 이루어져 왔다. 본 연구에서는 많은 전처리 과정을 생략하여 분석물의 손실을 최소화하면서 GC 및 GC/MSD를 이용하여 쉽고 빠르게 측정할 수 있는 조건과 방법을 확립하였다. 측정사료는 건강한 성인 남녀의 분변이었으며, 내부 표준물질로 4-isopropylphenol을 사용하였으며, 분변 중 indole의 함량은 10~90 ppm 수준이었으며, skatole의 경우에는 약 40 ppm 정도로 검출되었다. 또한, $\rho$-cresol은 30~300 ppm 수준으로 그 분포 범위가 아주 넓게 나타났었다. GC/MSD를 이용하여 시료 중상기 물질들을 정성적으로 정확히 확인할 수 있었다. DB-17 capillary 컬럼을 이용하여 시료의 전처리 과정을 생략하여도 분석하려던 부패산물의 정성 및 정량에 방해되는 불순 peak는 없었고, 분리능도 매우 우수하였으므로 보다 빠르고 신속하게 상기 물질들을 확인할 수 있었다. 향후 본 연구를 통해 개발된 신속분석법이 분변에 존재하는 주요 부패산물들의 정량에 유용하게 사용되리라 판단된다.

• Korean Chemical Engineering Research
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• 제56권2호
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• pp.252-260
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• 2018

Energy, a critical input, is to be efficiently managed via waste heat recovery and energy reuse for the economic viability of a process industry. In particular, cement manufacture demands a huge quantum of energy, for the necessary reactions. Huge amounts of hot effluent gases are generated. Energy recovery from these waste gases is an area that is of contemporary research interest. Now, about 75% of total heat recovery takes place in the riser of the suspension pre-heater system. This article deals with the hydrodynamic and heat transfer aspects of riser typically used in the cement industry. An experimental apparatus was designed and fabricated with provision for the measurement of gas pressure and solid temperatures at different heights of the riser. The system studied was air - chalcopyrite taken in different particle sizes. Acceleration length ($L_A$) determined at different parametric levels was fitted to an empirical correlation: $L_A/d_t=4.91902(d_p/d_t)^{0.10058}(w_s/w_g)^{-0.11691}(u_g{\mu}_g/d_t^2g{\rho}_g)^{0.28574}({\rho}_p/{\rho}_g)^{0.42484}$. An empirical model was developed for Nusselt number as a function of Reynolds and Prandtl numbers using regression analysis: $Nu=0.40969(Re_p)^{0.99953}(Pr)^{0.03569}$.

• Biomolecules & Therapeutics
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• 제22권6호
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• pp.540-546
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• 2014

The high mortality rates associated with cancer reflect the metastatic spread of tumor cells from the site of their origin. Metastasis, in fact, is the cause of 90% of cancer deaths. Therefore, considerable effort is being made to inhibit metastasis. In the present study, we screened ketotifen for anti-migratory and anti-invasive activities against MDA-MB-231 breast cancer and HT-1080 fibrosarcoma cancer cells. Cancer cell migration and invasion were measured using multi-well chambers. Additionally, western blots were used to examine the effects of ketotifen on the expressions of CDC42, Rho, Rac, and matrix metalloproteinase 9 (MMP-9). The results showed that ketotifen dose-dependently suppressed the migration and invasion of MDA-MB-231 and HT-1080 cells. Ketotifen also suppressed the expressions of CDC42, Rac, and Rho, which, significantly, are involved in MDA-MB-231 and HT-1080 cancer cell migration. Moreover, ketotifen suppressed the expression and activity of MMP-9, which is involved in degradation of the extracellular matrix leading to invasion. The overall data suggested that ketotifen suppresses the migration and invasion of MDA-MB-231 and HT-1080 cancer cells via inhibition of CDC42, Rac, Rho, and MMP-9 expression.

• 유통과학연구
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• 제20권10호
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• pp.11-17
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• 2022

Purpose: This research aims to find the link between public service Distribution and individual job performance in the provincial municipality. Research design, data, and methodology: This is a quantitative approach study with a non-experimental and correlational design. The sample consisted of 140 employees appointed and hired by the provincial municipality of Huaraz. For data collection, Two questionnaires with an ordinal Likert-type scale and the Rho Spearman correlation coefficient were used to assess the link between the research variables., For Analysis: two questionnaires with an ordinal Likert-type scale and the Rho Spearman correlation coefficient were used to determine the connection between the research variables. Results: It was determined that both variables have a high degree of correlation (0.725), indicating a direct and significant relationship between the Distribution of public service and skill performance in the provincial municipality (0.614). Conclusion: Finally, this allows us to conclude that the institutional context is essential; that is, there is a significant correlation between the PSM and contextual performance in the provincial municipality of Huaraz, which has a Rho Spearman value of 0.723.

• 한국약용작물학회지
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• 제2권3호
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• pp.234-240
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• 1994

우리나라에서 자생(自生)하고 있는 백리향(百里香)과 섬백리향(百里香)의 정유성분(精油成分)을 분석(分析) 비교(比較)코저 SDE방법(方法)에 의해 정유(精油)를 분리(分離)한 다음 GC-MS 및 GC에서 표준품(標準品)과의 머무름 시간(時間) 비교(比較)에 의해 성분(成分)을 확인(確認)한 결과(結果)는 다음과 같다. 1. 백리향(百里香)의 정유함량(精油含量)은 건물중앙(乾物重量)으로 1.94% 이었고, 섬백리향(百里香)의 경우 배엽부위(輩葉部位)에서는 1.91%인데 비하여 꽃에서는 0.68%이었다. 2. 3종류(種類)의 시료(試料)에서 38종(種)의 성분(成分)이 확인(確認)되었는데 그중 백리향(百里香)에서 분리(分離)한 정유(精油)에서는 thymol(39.8%), ${\gamma}-terpinene(10.0%)$, ${\rho}cymene(9.2%)$, camphor(5.9%), ${\alpha}-terpinene+borneol(4.5%)$ 및 bornyl acetate(4.0)가 주성분(主成分)이었고, 섬백리향(百里香)에서는 thymol(54.7%), ${\gamma}-terpinene(15.8%)$, ${\rho}cymene(6.7%)$ 및 carvacrol (3.2%)등이 주성분(主成分)이 었다. 3. 백리향(百里香)과 섬백리향(百里香)을 비교(比較)했을때 ${\alpha}-pinene,\;camphene,\;camphor,\;bornyl\;acetate$ 및 ${\alpha}-terpineol+borneol$ 등(等)은 백리향(百里善)에 서 많이 검출(檢出)된 반면 ${\gamma}-terpinene$, thymol은 섬백리향(百里香)에서 많이 검출(檢出)되었으며, 섬백리향(百里香)을 부위별(部位別)로 비교(比較)했을 때 thymol, ${\gamma}-terpinene$은 잎에서 많이 검출(檢出)되었으나 f-cymene은 잎보다는 꽃에서 특징적(特徵的) 으로 많이 검출(檢出)되는 경향(傾向)을 보였다.

• 한국잡초학회지
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• 제30권4호
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• pp.396-404
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• 2010

외래잡초인 돼지풀은 국내 확산이 우려되는 문제잡초로서 allelopathy와 관련성을 평가하기 위하여 돼지풀이 함유하고 있는 phenolic compounds의 시기별 변화와 이들 화합물에 의한 3종 잡초의 발아 및 초기생육을 평가하였다. 식물의 생육을 억제하는 물질로 잘 알려진 cinnamic acid 유도체인 5종의 페놀화합물은 HPLC를 이용하여 정량분석하였고, 4종 (caffeic acid, O-coumaric acid, ${\rho}$-coumaric acid 및 ferulic acid)의 화합물을 동정하였다. 돼지풀에서 검출된 페놀화합물 중 caffeic acid의 농도가 가장 높았으며, O-와 ${\rho}$-coumaric acid는 개화직전 농도가 개화후기보다 3배 정도 높았다. 돼지풀이 함유하고 있는 페놀화합물의 총함량은 개화직전이 $1,377{\mu}g$으로 개화후기의 $1,583{\mu}g$보다 낮았으나 돼지풀이 생장률에 비해 증가량은 현저히 낮았다. 표준용액을 이용하여 농도별로 조제한 페놀화합물 중 O-와 ${\rho}$-coumaric acid는 바랭이의 발아를 지연시켰으며, caffeic acid는 피의 발아율을 대조구보다 10% 억제시켰다. 또한 발아가 50%에 도달하는 시점을 나타내는 $T_{50}$는 $10^{-4}M$ 페놀화합물 처리구의 금방동사니와 바랭이에서 촉진되었으며, $10^{-3}M$ 페놀화합물 처리구의 금방동사니와 피에서 현저히 지연되었다. 다양한 페놀화합물 중에서 O-coumaric acid는 3종의 모든 잡초에서 하배축과 유근의 신장을 현저히 억제시켰으며, 금방동사니의 뿌리 세포 분열을 억제시켰고, 특히 피의 발근을 100% 억제시켰다.