• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.150.1-150.1
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• 2014

Showerhead is used as a main part in the semiconductor equipment. The face plate flatness should remain constant and the cleaning performance must be gained to keep the uniformity level of etching or deposition in chemical vapor deposition process. High operating temperature or long period of thermal loading could lead the showerhead to be deformed thermally. In some case, the thermal deformation appears very sensitive to showerhead performance. This paper describes the methods for robust design using computational fluid dynamics. To reveal the influence of the post distribution on flow pattern in the showerhead cavity, numerical simulation was performed for several post distributions. The flow structure appears similar to an impinging flow near a centered baffle in showerhead cavity. We took the structure as an index to estimate diffusion path. A robust design to reduce the thermal deformation of showerhead can be achieved using post number increase without ill effect on flow. To prevent the showerhead deformation by heat loading, its face plate thickness was determined additionally using numerical simulation. The face plate has thousands of impinging holes. The design key is to keep pressure drop distribution on the showerhead face plate with the holes. This study reads the methodology to apply to a showerhead hole design. A Hagen-Poiseuille equation gives the pressure drop in a fluid flowing through such hole. The assumptions of the equation are the fluid is viscous-incompressible and the flow is laminar fully developed in a through hole. An equation can be expressed with radius R and length L related to the volume flow rate Q from the Hagen-Poiseuille equation, $Q={\pi}R4{\Delta}p/8{\mu}L$, where ${\mu}$ is the viscosity and ${\Delta}p$ is the pressure drop. In present case, each hole has steps at both the inlet and the outlet, and the fluid appears compressible. So we simplify the equation as $Q=C(R,L){\Delta}p$. A series of performance curves for a through hole with geometric parameters were obtained using two-dimensional numerical simulation. We obtained a relation between the hole diameter and hole length from the test cases to determine hole diameter at fixed hole length. A numerical simulation has been performed as a tool for enhancing showerhead robust design from flow structure. Geometric parameters for the design were post distribution and face plate thickness. The reinforced showerhead has been installed and its effective deposition profile is being shown in factory.

• Clinical and Experimental Reproductive Medicine
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• 제28권4호
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• pp.265-270
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• 2001

Objective : The aim of this study was to evaluate the outcome the GnRH antagonist (Cetrotide) short protocol in controlled ovarian hyperstimulation comparing with GnRH agonist long protocol. Materials and Method: From July 2000 to November 2001, 26 patients, 28 cycles were performed in controlled ovarian hyperstimulation by GnRH antagonist and GnRH agonist. GnRH antagonist (Cetrotide) was administered in 12 patients (14 cycles, Group 1) and GnRH agonist (Lucrin, Sub Q, Group 2) in 14 patients (14 cycles). Ovulation induction was performed by hMG (Pergonal) in group 1, and by Combo (Metrodine HP + Pergonal) in group 2. We compared the fertilization rate, good quality embryo, and clinical pregnancy rate between the two groups. Student-t test and Chi-square were used to determine statistical significance. Statistical significance was defined as p<0.05. Results: Ovarian hyperstimulation syndrome did not occurred in which estradiol (E2) level was $3874{\pm}809\;pg/ml$ and the number of retrieved oocytes was $18.4{\pm}2.4$. The number of used gonadotropin ampules was significantly decreased in Group 1 (26.0 vs. 33.1, p<0.04). There were no significant difference in the number of preovulatory oocyte ($10.6{\pm}6.9$ vs. $10.0{\pm}6.1$), fertilization rate ($74.8{\pm}23.4$ vs. $72.2{\pm}21.8$), good quality embryo ($58.7{\pm}23.6$ vs. $38.7{\pm}36.6$), and embryo transfer ($4.3{\pm}1.6$ vs. $4.4{\pm}1.6$). Although the age of the group 1 was older than the group 2 (34.4 vs. 30.8), there was no significant difference in clinical pregnancy rate (50.0% vs. 57.1%). Conclusions: We suggest that GnRH antagonist was a safe, effective, and alternative method in the controlled ovarian hyperstimulation, especially in PCOD patients who will be develop the ovarian hyperstimulation syndrome.

• 한국정보통신학회논문지
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• 제25권12호
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• pp.1756-1761
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• 2021

2019년 12월경 후베이 우한시에서 발생한 코로나19 바이러스가 점차 줄어드는 듯 보였으나, 2020년 11월, 2021년 6월 기준으로 점차 늘어나고 있으며, 전세계적으로 총 1억 9천 2백만명, 대한민국 기준 총 확진자는 대략 18만4천명으로 추정된다. 이에 따른 대책으로 중앙재난안전대책본부는 사회적 거리두기 4단계를 시행하면서 강력한 대응책을 내고있지만, 델타바이러스등 전염성이 강한 코로나 변이 바이러스가 기승을 부리면서 국내 일일 확진자 수는 1800명대 까지 증가하게 되었다. 그에따라 코로나바이러스의 심각성을 강조하고자 코로나 누적 확진자 수를 ARIMA 알고리즘을 이용해 예측한다. 그 과정에서 추세와 계절성을 제거하기 위해서 차분을 이용하고, MA, AR, 자기상관함수와 편자기상관함수를 이용해 ARIMA에서 p,d,q값을 결정하고 예측한다. 마지막으로 예측값과 실제값을 비교해 얼마나 잘 예측되었는지 평가한다.

• 대한환경공학회지
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• 제22권7호
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• pp.1193-1203
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• 2000

본 연구는 흡착에 의한 Cd(II)의 제거를 위하여 일본 Diaion사에서 제조되고 있는 강산성양이온 교환수지(SK1B)를 흡착제로 사용하여 흡착평형실험, 탈착실험 및 흡착속도실험을 수행하였다. 흡착평형실험에서는 흡착능에 미치는 pH와 온도의 영향을 알아보았고 흡착등온식을 산출하였으며, 탈착실험에서는 재생회수에 대한 수지의 재생율의 변화에 대해서 알아보았다. 흡착속도실험에서는 수지를 미분층 반응기에 채워 유량별로 초기제거속도를 구하여 경막저항이 최소가 되는 최적유량을 구하였으며, 이 최적유량에서 흡착속도실험을 수행하여 총괄흡착속도식을 구하였다. 용액의 pH를 변화(2~7)시켜 제조하여 수지를 투여한 결과 pH가 증가할수록 흡착능이 증가하였으며 pH 6 이상에서는 흡착능이 일정한 경향을 나타내었다. 흡착능에 미치는 온도의 영향은 $10{\sim}50^{\circ}C$ 범위에서 온도가 증가할수록 흡착능도 증가함을 알 수 있었다. 회분식실험을 통해 얻은 자료를 각 흡착등온식에 적용해 본 결과 본 실험의 농도 영역(5~15ppm)에서는 Freundlich 흡착등온식과 Sips 흡착등온식이 Langmuir 흡착등온식보다 더 %편차가 적었다. 탈착제로서 0.01~2N 농도의 HCl 수용액을 사용할 경우에는 탈착제의 농도가 진할수록 흡착제의 재생율이 높았으며 재생 반복회수가 늘어날수록 재생율이 약간씩 감소하였다. 미분층 반응기를 이용한 연속공정실험($25{\pm}5^{\circ}C$)에서 경막확산저항이 최소가 되는 최적유량 $564m{\ell}/min$에서 수행한 수지에 대한 Cd(II) 수용액의 총괄흡착속도식은 다음과 같이 표현될 수 있다. $r=1.3785C_{fc}^{1.2421}-2.0907{\times}10^{0.0746C_i}\;q_e^{0.0121C_i-0.0301}$

• Asian-Australasian Journal of Animal Sciences
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• 제20권11호
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• pp.1670-1676
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• 2007

Fifty repeat breeder (RB) Friesian cows were allocated to five groups of 10 cows each, to determine the effect of progesterone (P4) supplement on P4 concentrations and pregnancy rates during the periods of corpus luteum (CL) formation and development between days 2-7 and 7-12 following a spontaneous or $PGF_{2{\alpha}}$-induced estrus. Cows were artificially inseminated during $PGF_{2{\alpha}}$-induced (PGF-P4-d2 and PGF-P4-d7 groups) or spontaneous (S-P4-d2, S-P4-d7, and control groups) estrus. Progesterone-releasing intravaginal device (PRID) devoid of estrogen capsule were inserted either on d 2 (PGF-P4-d2 and S-P4-d2 groups) or d 7 (PGF-P4-d7 and S-P4-d7 groups) post-insemination and left in place for 5 days. Control cows did not receive any treatment. Blood samples were collected for progesterone analysis from all cows once daily for 4 days starting on the day of estrus (d 0) and once every 3 days thereafter until d 22. Progesterone treatment by day interaction accounted for higher plasma P4 in treated than non-treated control cows. Progesterone concentrations differed significantly (p<0.05) during metestrus (d 2 to d 7) but not during diestrus (d 7 to d 12). $PGF_{2{\alpha}}$ treatment, lactation number, service number or their interactions did not affect progesterone concentrations and pregnancy rates. Therefore, cows were grouped according to the day of P4 supplement irrespective of the $PGF_{2{\alpha}}$ treatment. Progesterone supplement on d 7 but not d 2 significantly increased (p<0.03) pregnancy rates in repeat breeding cows with four or more previous services but not in cows in their third service. In conclusion, post-insemination P4 supplement to repeat breeding cows with four or more previous services improved pregnancy rates and should be advocated when no specific reason for infertility is diagnosed. Further studies with larger numbers of repeat breeding cows under field conditions are needed to ascertain the findings of this study.

• Korean Journal of Radiology
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• 제22권5호
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• pp.759-769
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• 2021

Objective: To evaluate the application of laplacian-regularized mean apparent propagator (MAPL)-MRI to brain glioma-induced corticospinal tract (CST) injury. Materials and Methods: This study included 20 patients with glioma adjacent to the CST pathway who had undergone structural and diffusion MRI. The entire CSTs of the affected and healthy sides were reconstructed, and the peritumoral CSTs were manually segmented. The morphological characteristics of the CST (track number, average length, volume, displacement of the affected CST) were examined and the diffusion parameter values, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), mean squared displacement (MSD), q-space inverse variance (QIV), return-to-origin probability (RTOP), return-to-axis probabilities (RTAP), and return-to-plane probabilities (RTPP) along the entire and peritumoral CSTs, were calculated. The entire and peritumoral CST characteristics of the affected and healthy sides as well as those relative CST characteristics of the patients with motor weakness and normal motor function were compared. Results: The track number, volume, MD, RD, MSD, QIV, RTAP, RTOP, and RTPP of the entire and peritumoral CSTs changed significantly for the affected side, whereas the AD and FA changed significantly only in the peritumoral CST (p < 0.05). In patients with motor weakness, the relative MSD of the entire CST, QIV of the entire and peritumoral CSTs, and the AD, MD, RD of the peritumoral CST were significantly higher, whereas the RTPP of the entire and peritumoral CSTs and the RTOP of the peritumoral CST were significantly lower than those in patients with normal motor function (p < 0.05 for all). In contrast, no significant changes were found in the CST morphological characteristics, FA, or RTAP (p > 0.05 for all). Conclusion: MAPL-MRI is an effective approach for evaluating microstructural changes after CST injury. Its sensitivity may improve when using the peritumoral CST features.

• Journal of Ecology and Environment
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• 제29권6호
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• pp.531-537
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• 2006

본 연구는 월악산 국가장기생태연구지소를 중심으로 이 지역에서 다른 개체군에 비하여 상대적으로 광역 우점하는 소나무림, 굴참나무림, 그리고 신갈나무림 등 3개 주요 임분을 대상으로 그들의 종조성과 구조적 특성을 평가하였다. 종 및 개체수는 분포 경향은 흉고직경급이 증가할수록 감소하는 경향을 나타내었으며, 종 풍부성에 있어서 다양한 입지 적응 폭을 가지고 있는 신갈나무림이 다른 두 임분에 비하여 상대적으로 높게 나타남을 알 수 있었다. 천이 경향은 임분별로 천이 단계상 다소 차이가 있지만 장기적으로 보면 임분 유형에 관계없이 모두 신갈나무림으로 변화될 것으로 판단되었다. 각 임분의 우점종을 기준으로 생목과 사목의 개체 밀도 구성비를 보면 신갈나무림에서 신갈나무 개체 75:25, 굴참나무림에서 굴참나무 개체 94:6, 그리고 소나무림에서 소나무 86:14로 신갈나무림에서 개체 고사율이 가장 높고 굴참나무림이 가장 낮게 나타났다. 이것은 각 임분의 천이 단계의 차이에 따른 종간 및 종내 경쟁의 결과로 판단되었다. 한편, 임분별 구성 개체목의 건강 상태를 보면 임분유형에 관계없이 AS형이 75$\sim$85%로 가장 높게 나타났으며 DF형은 전혀 나타나지 않았다. 끝으로 본 연구를 위해 설치한 영구 방형구는 향후 정기적인 조사를 통하여 이 지역 산림 생태계 보전에 적합한 유용 정보를 제공하여 줄 수 있을 것이다.

• Journal of Ginseng Research
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• 제45권1호
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• pp.149-155
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• 2021

Background: We have reported that internal deletions in the nef, gag, and pol genes in HIV-1-infected patients are induced in those treated with Korean Red Ginseng (KRG). KRG delays the development of resistance mutations to antiretroviral drugs. Methods: The vif-vpr genes over 26 years in 20 hemophiliacs infected with HIV-1 from a single source were sequenced to investigate whether vif-vpr genes were affected by KRG and KRG plus highly active antiretroviral therapy (ART) (hereafter called GCT) and compared the results with our previous data. Results: A significantly higher number of in-frame small deletions were found in the vif-vpr genes of KRG-treated patients than at the baseline, in control patients, and in ART-alone patients (p < 0.001). These were significantly reduced in GCT patients (p < 0.05). In contrast, sequences harboring a premature stop codon (SC) were more significant in GCT patients (10.1%) than in KRG-alone patients, control (p < 0.01), and ART-alone patients (p = 0.078 for peripheral blood mononuclear cells). The proportion of SC in Vpr was similar to that in Vif, whereas the proportion of sequences revealing SC in the env-nef genes was significantly lower than that in the pol-vif-vpr genes (p < 0.01). The genetic distance was 1.8 times higher in the sequences harboring SC than in the sequences without SC (p < 0.001). Q135P in the vif gene is significantly associated with rapid progression to AIDS (p < 0.01). Conclusion: Our data show that KRG might induce sD in the vif-vpr genes and that vif-vpr genes are similarly affected by lethal mutations.

• 대한전기학회논문지:전력기술부문A
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• 제48권12호
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• pp.1514-1519
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• 1999

This paper presents two flexible alternatives to the decoupled load flow(DCL) method. The proposed load flow methods can improve the convergence profiles of the DCL by reflecting in part the effects of the off-diagonal terms in the Jacobian at minimal costs. They can improve the convergence characteristics especially when the power system operating states deviate from the conditions required for stable convergence of the DCL and the P-Q coupling becomes significant. Two algorithms are obtained from the expression of the full Newton-Raphson load flow (NRL) method by successively diminishing the effects of the off-diagonal submatrices in the Jacobian. In the process of simplification, the Neuman series expansion is utilized. Test results show promising performances of the proposed algorithms in their convergence characteristics both in number of iterations and overall convergence speeds. Proposed algorithms are expected to provide flexible alternatives to the NRL when the DCL experiences convergence problems.

• 대한수학회지
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• 제44권6호
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• pp.1313-1327
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• 2007

We review the algebraic structure of $\mathbb{H}{\sharp}$ and show that $\mathbb{H}{\sharp}$ has a scalar product that allows as to identify it with semi Euclidean ${\mathbb{E}}^4_2$. We show that a pair q and p of unit split quaternions in $\mathbb{H}{\sharp}$ determines a rotation $R_{qp}:\mathbb{H}{\sharp}{\rightarrow}\mathbb{H}{\sharp}$. Moreover, we prove that $R_{qp}$ is a product of rotations in a pair of orthogonal planes in ${\mathbb{E}}^4_2$. To do that we call upon one tool from the theory of second ordinary differential equations.