• Environmental Engineering Research
• /
• 제14권1호
• /
• pp.48-52
• /
• 2009

Solubilization of sewage sludge creates favorable conditions for anaerobic microorganisms to produce biogas. In this paper, we quantify the effect of heating pretreatment on the degree of solubilization of sewage sludge. The pretreatment process was carried out using a lab-scale industrial microwave unit (2450 MHz frequency). Response surface analysis was applied to determine the combination of temperature-increase rate (ramp rate) (2.9 to 17.1 ${^{\circ}C}$/min) and terminal temperature (52 to 108${^{\circ}C}$). Both ramp rate and temperature significantly affected the solubilization degree of sludge. Within the design boundaries, the conditions predicted to maximize the solubilization degree of 15.8% were determined to be 2.9 ${^{\circ}C}$/min and 104${^{\circ}C}$.

• 한국감성과학회:학술대회논문집
• /
• 한국감성과학회 2000년도 추계학술대회 논문집
• /
• pp.148-154
• /
• 2000

To do this study, we produced cooling vest newly. Rectal temperature was ascended approximately from 37.2$^{\circ}C$ to 38.05$^{\circ}C$ in lab, but wearing cooling vest, the temperature was descended 0.2 while wearing developed product compare with existing product. Mean skin temperature which was showed distribution from 32.8∼36.5$^{\circ}C$, it was descended 1.0∼1.1$^{\circ}C$, while wearing cooling vest and comparing with existing product, wearing developed product was lower 0.5$^{\circ}C$, While wearing developed product, it was found that they had lower tendency than exiting product. Specifically in case of temperature within clothing(chest) 0.2∼2.0$^{\circ}C$ in case of humidity within clothing 2∼8% RH. Facts from above we confirmed that clothing microclimate had been improved and space was happened between body and garment in order to control. In subjective sensation, existing product made negative response during experiment period from participants, but developed product was nearing to comfortable area.

• International Journal of Precision Engineering and Manufacturing
• /
• 제9권4호
• /
• pp.51-56
• /
• 2008

Thermoforming is one of the most versatile and economical processes available for shaping polymer products, but obtaining a uniform thickness of the final product using this method is difficult. Heater power adjustment is very important because the thickness distribution depends strongly on the distribution of the sheet temperature. In this paper, the steady-state optimum distribution of heater power is first ascertained by a numerical optimization to obtain a uniform sheet temperature. The time-dependent optimal heater input is then determined to decrease the temperature difference through the direction of the thickness using the response surface method and the D-optimal method. The optimal results show that the time-dependent optimum heater power distribution gives an acceptable uniform sheet temperature in the forming temperature range by the end of the heating process.

• Advanced Composite Materials
• /
• 제17권2호
• /
• pp.111-124
• /
• 2008

The effect of temperature on natural frequency and damping is investigated in two different composite materials, Kevlar 29 fiber woven and polyethylene cloth, used especially to design ballistic armor. A damping monitoring method is used experimentally to measure the frequency response curve and it is also modeled numerically using a finite element program. The natural frequencies of a material, or a system, are a function of its elastic properties, dimensions and mass. This concept is used to calculate theoretical vibration modes of the composites. The damping properties in terms of the damping factor are determined by the half-power bandwidth technique. Numerically analyzed and experimentally measured time response curves are compared. It is seen that polymer matrix composites have temperature dependent mechanical properties. This relationship is functional and they have different effects against temperature.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2003년도 춘계학술대회 논문집
• /
• pp.62-67
• /
• 2003

In this Paper, the dynamic temperature sensitivity and mu. temperature measurement errors of oil and air sensor in oil cooler are evaluated to predict design validity of sensors under special oil and atmosphere temperature changes. The temperature tracking of oil sensors for periodic temperature changes is simulated by obtaining thermal response coefficient from experiment. By this method, it is possible to design the optimal sensors with the admitted temperature measurement errors.

• 한국양식학회지
• /
• 제12권3호
• /
• pp.221-228
• /
• 1999

The effects of sparp changes of water temperature (WT) on the stree response and physiological change of the cultured olive flounder (Paralichthys olivaceus) were examined by manipulating WT (3 patterns) in a running seawater culture system. In the first group (Exp. I), the WT was decreased from 18$^{\circ}C$ to 11$^{\circ}C$ within 6 hours and increased back to the original WT quickly. WT was decreased from 2$0^{\circ}C$ to 11$^{\circ}C$ within 5 hours and main-tained at 11$^{\circ}C$ for 10 hours. and then increased to 2$0^{\circ}C$ in the second group (Exp. II). In the third group(Exp. III) WT was decreased to 11$^{\circ}C$ within 5 hours (type A) or 10 hrs. (type B). In Exp. I and III, the level of serum cortisol was increased from 2.5$\pm$0.3 ng/ml and 2.6$\pm$0.9 ng/ml to 13.6$\pm$3.0 ng/ml and 12.4$\pm$3.2ng/ml, respectively, with WT decrease. However, no consistent tendency in the change of serum glucose level was shown according to WT decrease. In Exp. III, the glucose level of fish in type A was decreased until 5 hours and increased at 7 hours, then decreased until 12 hours where as the glucose level in type B was decreased until 5 hours and stayed at the level of 15.7 mg/dl. The serum osmolality was reduced with WT decrease and the response of serum electrolytes in this experiment conflicted, and a tendency in total protein, AST and ALT was not found following WT decrease. In conclusion, olive flounder responded to the stress caused by WT decrease and acclimated to this condition when the lower temperature was maintained. But there was no stress response in the blood of olive flounder when WT was increased. On the other hand, the degree of stress response in olive flounder was various according to the range and gradient of WT change.

• 대한간호학회지
• /
• 제30권2호
• /
• pp.488-497
• /
• 2000

The purpose of this study was to explore the effect of a postpartum massage program on stress response in the Cesarean section mothers. The study focused on evaluating the effect of postpartum massage program on mood, anxiety, skin temperature and concentration of saliva and breast milk immunoglobulin A in the Cesarean section mothers. This study was designed as a nonequivalent control group pretest-posttest quasi-experimental study. Twenty-eight Cesarean section mothers were selected as experimental group, whereas twenty- seven were control group. The postpartum massage program consisted of 20 minutes of warm-up, massage and ending phases and used once a day. During each program, there were 4 minutes of warm-up, 14 minutes of massage on back, axillary and breasts, and 2 minutes of ending. Massage were used for the experimental group by the same investigator 20 times per minute. The massage technique used were efflurage, petrissage, accupressure, kneading and vibration. Skin temperature was monitored with YSI Tele-thermometer(Simpson electric Co., USA) before and after massage program. The concentration of immunoglobulin A in saliva and breast milk was analyzed by immunoturbididimeter assay(Cobas INTEGRA, Swiss) before and after massage program. Also at this time mood and anxiety were measured by self-report. The data were analyzed using SPSS version 7.5 and hypothesis was tested with ANCOVA analysis and Pearson coefficient correlation. The results were as follows : 1) Score of mood increased significantly after use of postpartum massage program. 2) Level of anxiety decreased significantly after use of postpartum massage program. 3) Skin temperature increased significantly after use of postpartum massage program. 4) Concentration of saliva immunoglobulin A increased significantly after use of postpartum massage program. 5) Concentration of breast milk immunoglobulin A did not change significantly after use of postpartum massage program. 6) After use of postpartum massage program, there was significant correlation between psychological stress response and physiological stress response.The results suggest that postpartum massage program can be effective nursing intervention to reduce stress response in the postpartum mothers under stress.

• Journal of Microbiology and Biotechnology
• /
• 제17권4호
• /
• pp.644-649
• /
• 2007

Response surface model was developed for predicting the growth rates of Salmonella enterica sv. Typhimurium in tryptic soy broth (TSB) medium as a function of combined effects of temperature, pH, and NaCl. The TSB containing six different concentrations of NaCl (0, 2, 4, 6, 8, and 10%) was adjusted to an initial of six different pH levels (pH 4, 5, 6, 7, 8, 9, and 10) and incubated at 10 or $20^{\circ}C$. In all experimental variables, the primary growth curves were well $(r^2=0.900\;to\;0.996)$ fitted to a Gompertz equation to obtain growth rates. The secondary response surface model for natural logarithm transformations of growth rates as a function of combined effects of temperature, pH, and NaCl was obtained by SAS's general linear analysis. The predicted growth rates of the S. Typhimurium were generally decreased by basic (9, 10) or acidic (5, 6) pH levels or increase of NaCl concentrations (0-8%). Response surface model was identified as an appropriate secondary model for growth rates on the basis of coefficient determination $(r^2=0.960)$, mean square error (MSE=0.022), bias factor $(B_f=1.023)$, and accuracy factor $(A_f=1.164)$. Therefore, the developed secondary model proved reliable predictions of the combined effect of temperature, NaCl, and pH on growth rates for S. Typhimurium in TSB medium.

• Structural Engineering and Mechanics
• /
• 제51권5호
• /
• pp.755-771
• /
• 2014

Environmental changes, especially global climate change, are creating new challenges to the development of the Arctic regions, which have substantial energy resources. And attention to offshore structures has increased with oil and gas development. The structural impact response of an explosion-resistant profiled blast walls normally changes when it operates in low temperatures. The main objectives of this study are to investigate the structural response of blast walls in low temperature and suggest useful guidelines for understanding the characteristics of the structural impact response of blast walls subjected to hydrocarbon explosions in Arctic conditions. The target temperatures were based on the average summer temperature ($-20^{\circ}C$), the average winter temperature ($-40^{\circ}C$) and the coldest temperature recorded (approximately $-68^{\circ}C$) in the Arctic. The nonlinear finite element analysis was performed to design an explosion-resistant profiled blast wall for use in Arctic conditions based on the behaviour of material properties at low temperatures established by performing a tensile test. The conclusions and implications of the findings are discussed.

• 한국산학기술학회논문지
• /
• 제17권1호
• /
• pp.28-35
• /
• 2016

지열원 히트펌프 시스템에서 지중 열교환기 설계를 위해 수행하는 현장 열응답 시험은 많은 시간과 비용이 수반되기 때문에 조건 변화에 따른 출구온도 예측이 어려운 실정이다. 본 연구에서는 국내에서 주로 사용하는 수직형 지중 열교환기의 열전달 성능을 예측하기 위한 방안으로 3차원 CFD 해석 기법을 제안하고, 2개소의 현장 열응답 시험의 출구온도와 기울기 값을 비교하여 CFD 해석 방법의 신뢰성을 확인하였다. CFD 해석 결과, 2개소의 현장 열응답 시험의 출구온도는 $0.5^{\circ}C$ 이내에서 예측하였고, 기울기 값은 1.6% 이내에서 적절히 예측하였다. 이를 통해 CFD 해석 방법의 신뢰성을 확인하고, 2개소의 현장 열응답 시험의 유량 및 지중 유효 열전도도 조건을 각각 ${\pm}20%$ 변화시키면서 현장 열응답 시험의 출구온도를 예측하였다. 첫 번째 현장(Case 1)의 경우 유량 변화에 따라 $28.0^{\circ}C$(-20%)와 $29.6^{\circ}C$(+20%), 지중 유효 열전도도 변화에 따라 $29.6^{\circ}C$(-20%)와 $28.0^{\circ}C$(+20%)로 현장 열응답 시험의 출구온도를 예측하였으며, 두 번째 현장(Case 2)의 경우 유량 변화에 따라 $28.4^{\circ}C$(-20%)와 $29.8^{\circ}C$(+20%), 지중 유효 열전도도 변화에 따라 $29.7^{\circ}C$(-20%)와 $28.4^{\circ}C$(+20%)로 현장 열응답 시험의 출구온도를 각각 예측하였다.