• Clinical and Experimental Reproductive Medicine
• /
• 제30권1호
• /
• pp.39-45
• /
• 2003

Objective : To identify the factors affecting the complete fetal loss following multifetal pregnancy reduction (MFPR). Design: Retrospective clinical study. Methods : A total of 256 consecutive treatments of MFPR in IVF-ET cycles performed between 1992 through 2000 in Samsung Cheil hospital were analyzed. MFPR was done around 8 weeks of gestation by transvaginal ultrasono-guided aspiration in multiple pregnancies and reduced to singleton or twins. Stepwise logistic regression was performed to identify the factors affecting the final outcome of pregnancy after MFPR. Dependent variable was complete fetal loss and the independent variables were maternal age, paternal age, initial number of gestational sac (iGSNO), initial number of fetal heart beat, the number of remaining live fetus after MFPR, and chorionicity. Results: The total survival rate was 87.9%, and total fetal loss rate after MFPR was 12.1%. Total fetal loss occurred within four weeks from MFPR procedure was 1.95%. Total loss occurred after four weeks of procedure and before 24 gestational weeks was 8.2%. Seventy nine percent (202/256) of pregnancies delivered after 34 weeks of gestation. The survival rate of pregnancies reduced to singleton was significantly higher than that of pregnancies reduced to twins (93.5% vs. 86.7%, p<0.05). The mean ($\pm$SEM) gestational age at delivery was $36.2{\pm}1.0$ and $34.1{\pm}0.5$ weeks for pregnancies reduced to singletons and twins, respectively (p=0.065). Logistic regression analysis revealed that the maternal age, the number of initial gestational sac (iGSNO), and the number of remaining live fetus after MFPR significantly affected the rate of total fetal loss (Z = 0.174'age + 0.596'iGSNO + 1.324'remaining fetuses -12.07), (p<0.05). Conclusions: MFPR seems to be a relatively safe and efficient method to improve the obstetric outcome in high order multiple pregnancy. Because the maternal age, the number of initial gestational sac and the remaining live fetuses after MFPR affect the total fetal loss rate, restriction of the number of transferred embryos according to the age and MFPR to singleton fetus could be considered for the better obstetric outcome in IVF pregnancy.

• 대한토목학회논문집
• /
• 제32권1B호
• /
• pp.79-84
• /
• 2012

질산성질소는 일반적인 지하수 오염물질로서, 본 연구에서는 영가철을 충진한 복극전해조를 이용하여 서로 다른 조건에서 질산성질소 제거실험을 수행하였다. 실험에 사용된 전해조에는 양쪽 끝에 위치한 주 전극 사이에 전도체로서 영가철이, 비전도체로서 규사가 혼합하여 충진되었다. 모의폐수(오염된 지하수를 모사하였으며 초기 질산성질소 농도 약 30 mg/L, 전기전도도 약 300 ${\mu}S/cm$)를 이용한 연속식 실험에서 인가전압 600 V, 유입유량 20 mL/min으로 최대 99% 이상의 질산성질소를 제거하였다. 최적 혼합비 및 최적 유입유량은 각각 1:1~2:1(규사:영가철), 30 mL/min으로 결정하였다. 질산성질소의 주입농도에 따라 유출수의 pH가 비례적으로 거동하였으며, 질산성질소 환원의 최종산물로서 약 60% 정도가 암모니아로 유출되었다. 실험이 끝난 후 영가철 표면에서의 산화철은 대부분 magnetite형태로 존재하였다.

• 한국해양공학회지
• /
• 제25권1호
• /
• pp.32-38
• /
• 2011

Galvanized steel has gone through a chemical process to keep it from corroding. The steel gets coated in layers of zinc because rust will not attack this protective metal. For countless outdoor, marine, or industrial applications, galvanized steel is an essential fabrication component. The reduction of the corrosion rate of zinc is an important topic. In the past, a very popular way to reduce the corrosion rate of zinc was to use chemical conversion layers based on $Cr^{+6}$. However, a significant problem that has arisen is that the use of chromium salts is now restricted because of environmental protection legislation. Therefore, it is very important to develop new zinc surface treatments that are environmentally friendly to improve the corrosion resistance of zinc and adhesion with a final organic protective layer. In this study, a Urethane solution (only Urethane 20 wt.%; S-700) and an organic/inorganic solution with Si (Si polysilicate 10 wt.% + Urethane 10 wt.%; LRO-317) are used. Based on the salt spray test of 72 h, S-700 and LRO-317 had a superior effect for the corrosion resistance on EGI and HDGI, respectively.

• Clinics in Shoulder and Elbow
• /
• 제23권1호
• /
• pp.20-26
• /
• 2020

Background: High complication rate after open reduction and internal fixation can lead to use of primary total elbow replacement (TER) in treatment of complex distal humerus fractures in elderly patients. The purpose of this study was to investigate the short-term outcomes and complications after primary TER in patients with complex distal humerus fracture. Methods: Nine patients with acute complex distal humerus fracture were treated by primary TER using the semiconstrained Coonrad-Morrey prosthesis. The mean age of patients was 72.7 years (range, 63-85 years). Clinical and radiographic outcomes were evaluated over a mean follow-up of 29.0 months (range, 12-65 months) using visual analog scale (VAS) score for pain; Mayo elbow performance score (MEPS); Quick Disabilities of the Arm, Shoulder, and Hand (Quick-DASH) score; and serial plain radiographs. Complications were also evaluated. Results: At the final follow-up, mean VAS, MEPS, and Quick-DASH scores were 1.2, 80.5, and 20, respectively. The mean range of motion was 127.7° of flexion, 13.8° of extension, 73.3° of pronation, and 74.4° of supination. There was no evidence of bushing wear or high-grade implant loosening on serial plain radiographs. Three complications (33.3%) comprising two periprosthetic fractures and one ulnar neuropathy were observed. Conclusions: Primary TER for treatment of complex distal humerus fractures in elderly patients yielded satisfactory short-term outcomes. However, surgeons should consider the high complication rate after primary TER.

• 한국어류학회지
• /
• 제20권2호
• /
• pp.81-89
• /
• 2008

메기, Silurus asotus에서 포식과 기아가 생존과 성장, 내장괴지수, 간중량지수, 생식소중량지수, 외형계측형질 변화 및 혈액 parameter들에 미치는 영향을 파악하기 위해 80일동안 기아 실험을 수행하였다. 기아군의 생존과 성장은 포식군의 생존과 성장에 비해 낮았다(P<0.05). 기아는 체중성장률, 일간성장률과 비만도에서 성장 정지 효과를 나타낸 반면, 포식군은 지속적인 성장을 보였다. 외형 계측형질 중복강 부위 횡단길이 관련에서 포식군은 실험 시작시와 차이를 보이지 않았으나, 기아군은 차이를 나타냈다 (P<0.05). 실험 기간 중 혈액성상(cortisol, glucose, AST, ALT, RBC 및 hemoglobin)에서 포식군과 기아군 사이에 유의한 차이를 보였다. 본 연구 결과, 포식과 기아 파악에 사용된 모든 parameter들은 본 종의 영양 상태 확인의 지표로 유용하며, 양식 메기의 성장 시기 평가 결정에 유용하리라 사료된다.

• 상하수도학회지
• /
• 제23권4호
• /
• pp.471-479
• /
• 2009

A Nanoscale Zero-Valent Iron(NZVI) was modified to build a reactor system to treat nitrate. Shell layer of the NZVI was modified by slow exposure of the iron surface to air flow, which produced NZVI particles that are resistant to aerial oxidation. A XANES (X-ray Absorption Near-Edge Structure) analysis revealed that the shell consists of magnetite ($Fe_3O_4$) dominantly. The shell-modified NZVI(0.5 g NZVI/ 120 mL) was able to degrade more than 95% of 30 mg/L of nitrate within $30 hr^{-1}$ ( pseudo first-order rate constant($k_{SA}$) normalzed to NZVI surface area ($17.96m^2/g$) : $0.0050L{\cdot}m^{-2}{\cdot}hr^{-1}$). Ammonia occupied about 90% of degradation products of nitrate. Nitrate degradation efficiencies increased with the increase of NZVI dose generally. Initial pH values of the reactor systems at 4, 7, and 10 did not affect nitrate removal rate and final pH values of all experiments were near 12. Nitrate removal experiments by using the shell-modified NZVI immobilized on a cellulose acetate (CA) membrane were also conducted. The nitrate removal efficiency of the CA membrane supported NZVI ($k_{SA}=0.0036L{\cdot}m^{-2}{\cdot}hr^{-1}$) was less than that of the NZVI slurries($k_{SA}=0.0050L{\cdot}m^{-2}{\cdot}hr^{-1}$), which is probably due to less surface area available for reduction and to kinetic retardation by nitrate transport through the CA membrane. The detachment of the NZVI from the CA membrane was minimal and impregnation of up to 1 g of NZVI onto 1 g of the CA membrane was found feasible.

• 한국자동차공학회논문집
• /
• 제13권2호
• /
• pp.72-82
• /
• 2005

The objective of this paper is to describe the optimization of design parameters in a large-sized commercial bus heater system by using CFD(computational fluid dynamics) analysis and Taguchi method. In order to obtain the best combination of each control factor which results in a desired performance of heater system, the parameter design of the Taguchi method is adopted for the robust design considering the dynamic characteristic. The research activity may be divided into four phases. The first one is analyzing the problem, i.e., ascertaining the influential factors. In the second phase the levels were set in such a way that their variation would significantly influence the response. In the third phase the experimental runs were designed. In the final phase the planned runs were carried out numerically to evaluate the optimal combination of factors which is able to provide the best response. In this study, eight factors were considered for the analysis: one with two level and seven with three level combinations comprising the $L_{18}(2^1{\times}3^7)$ orthogonal array. The results of this study can be summarized as follows ; (i)The optimum condition of control factor is a set of <$A_2\;B_1\;C_3\;D_3\;E_1\;F_2\;G_3\;H_2$> where A is shape of the outer fin, B is pitch of the outer fin, C is height of the outer fin, D is the inner fin number, E is the inner fin height, F is length of the flame guide, G is diameter of the heating element and H is clearance between air guide and heating element. (ii)The heat capacity of heated discharge air under the optimum condition satisfies the equation y=0.6M w here M is a signal factor. (iii)The warm-up rate improves about three times, more largely as com pared with the current condition, which results in about 9.2minutes reduction.

• 한국양식학회지
• /
• 제19권3호
• /
• pp.183-187
• /
• 2006

넙치, Paralichthys olivaceus (Temminck et Schlegel)에서 급이와 절식이 생존과 성장 및 표현형질에 미치는 영향을 파악하기 위해 12주에 걸친 급이와 절식 실험을 수행하였다. 실험 기간중 절식군의 생존율은 급이군에 비해 낮았다. 기아는 비만도, 일일성장률, 체중 성장률 및 실험 종료시 체중에서의 감소를 보이는 성장 저해를 나타낸 반면, 급이군은 지속적이고 양호한 성장을 보였다. 절식군은 급이군에 비하여 유사한 dressing비와 내장괴지수를 보였으며, 낮은 내장괴제거 체중을 보였다(P<0.05). 본 연구 결과, 급이와 절식 파악에 사용된 표현형질은 본 종의 영양 상태 확인의 지표로 유용하며, 넙치 표본시의 성장 시기 평가 결정에 유용하리라 사료된다.

• 한국환경과학회지
• /
• 제23권4호
• /
• pp.681-695
• /
• 2014

In a pilot-scale dyeing wastewater treatment using two-type fluidizing media, each thickness of biofilm was 15 and 30 ${\mu}m$, respectively. The numbers of protozoa inhabited in small-size (PEMT A) and big-size (PEMT B) media were $7.5{\times}10^4$ and $1.25{\times}10^5$ cells/ml, respectively, and dominant species were Entosiphon sulcatus var sulcatus in PEMT A and Chlamydomonas reinhardtii in PEMT B, respectively. Flask experiments using the two media revealed that the percentages of color removal were 25.8% in PEMT A and 27.1% in PEMT B after 72-h cultivation, indicating the necessity of bioaugmentation. Experiments for bioaugmentation effect on color removal were carried out in the pilot-scale treatment for 75 d by three-step operation under the control of wastewater loading rate and microbial input rate. Dye degradation occurred mainly in the second reaction tank, and the attachment of augmented dye-degrading microorganisms to media took at least 35 d. Final value of chromaticity in effluent was 227, meeting the required standard. Therefore bioaugmentation onto media was good for color treatment. In summary, thickness of biofilm formed on the media depended upon the size of media, resulting in different ecosystem inside the media. Hence, this affected microbial community and color treatment further. Accordingly, the reduction of operation cost is expected by efficient color-treatment process using bioaugmented media.

• 자원ㆍ환경경제연구
• /
• 제16권2호
• /
• pp.275-311
• /
• 2007

수소에너지는 비고갈성 청정에너지로 향후 탄소기반의 에너지 시스템을 대체할 에너지로 주목받고 있다. 정부의 장기적인 비전도 수소에너지의 최종에너지 수요 비중을 2040년까지 15%로 확대한다는 것이나 이를 달성하기 위해서는 200조 원이 넘는 엄청난 비용이 수반된다. 본 연구는 동태 CGE 모형을 적용하여 수소에너지 보급에 따라 한국경제에 어떤 영향을 미칠 것인지를 분석하였다. 프런티어 기술로서 수소에너지는 학습효과와 에너지원간 상보성(complementarity)의 영향으로 정부지원 없이는 2040년 기준으로 최종에너지 수요의 6.5%에 그칠 전망이나 정부가 수소에너지에 대해 각각 10%, 20%, 30%의 가격보조 정책을 실시할 경우 9.2%, 15.2%, 37.7%로 증가할 것으로 분석되었다. 즉, 정부개업을 통해 수소기술 확산 지연 현상이 크게 완화될 수 있음을 보여주는 것이다. 한편 수소기술의 주요 응용분야인 수송부문의 성장이 두드러지나 수송 연료의 대부분을 차지하는 석유가 수소에너지로 대체됨으로써 석유부문에 대한 소비가 감소하고, 발전부문의 비중도 감소하는 것으로 나타났다. 정부의 가격보조가 가계소득에서 충당되는 것으로 가정했기 때문에 가격하락에 의한 소비증가효과가 소득감소에 따른 소비감소에 의해 상쇄되면서 가계의 최종소비도 부정적 영향을 받는 것으로 분석되었다. 그러나 전반적인 생산, 투자, 수출 증가에 힘입어 GDP 수준은 소폭 성장하다가 2040년 무렵에 소폭 감소하여 경제 전반에 미치는 영향은 미미할 것으로 분석되었다.