Earticle

Welding is a representative processing technology applied in many industrial sites due to its quality and convenience. In particular, fiber laser welding can be welded at a faster speed compared to arc welding, and there is an advantage in welding distortion, which is the most significant disadvantage of welding. In this study, the weldable thickness was predicted, and the optimal welding angle was estimated using simulations during the welding of the T-shape structure. The multi-layer heat source model proposed in the previous author's study was used, and the study was conducted using the proposed welding heat source under specific conditions of 4kw and 1.0m/min. As a result, it was predicted that high-quality welding would be possible when the thickness was 3mm or 4mm, and it was also confirmed that welding should be performed at an angle of 82.5° or more when welding a 3mm thick structure. As a follow-up study, we plan to build a welding heat source model under various conditions and conduct a study to derive welding conditions at various thicknesses.

While the vehicle has a wide front view, making it easy to recognize obstacles while driving, the rear side has a narrow view and the inconvenience of having to turn its head to check. A side mirror developed to address this discomfort is mounted outside the front door of a passenger car and used to identify rear objects. In this study, heat transfer analysis was performed and analyzed in order to obtain optimal defrost conditions using regression analysis method for removing mirror condensation and frost. As a result of this study, the coefficient of determination, R2, which represents the regression to the total variation through regression analysis, showed a good reliability of 85.3%. Comparing the predicted and interpreted values of the maximum temperature distribution in the regression equation established in this study, it was included in the 95% confidence interval, enabling the prediction of the maximum temperature distribution over the heat conduction time.

For the development of a new antidementia functional food or alternative drug using agricultural products, Job's tears (Coix lachrymajobi L.), which shows high acetylcholinesterase (AChE) inhibitory activity (55.1%) was selected and the extraction conditions of AChE inhibitor were optimized. AChE inhibitor of Job's tears was maximally extracted when it was treated with 60% methanol at 40℃ for 6 h. The AChE inhibitor of the methanol extracts was partially purified by systematic solvent extraction, thin layer chromatography, silica gel chromatography and reverse-phase HPLC and the partial purified AChE inhibitor with inhibitory activity (IC50) of 0.608 ㎍ was obtained. The partial purified AChE inhibitor was soluble in methanol and hexane, and insoluble in water. Its maximum absorption spectra was 230 ㎚ and also it was stable in the range of 30℃ and 70℃ and pH 4.0-8.0 for 1 h.

Overweight and obesity induce serious health problems that exert negative effects on dog’s welfare. Body condition score (BCS) is a common method to evaluate the body fat mass in animals. By palpating and observing fats under the skin it is possible to predict animal’s body fat accumulation condition. BCS is also a useful tool to estimate body fat composition in dogs. However, BCS can be subjective when it was performed by non-professionals like pet’s owners. To develop a method to avoid the misevaluation of BCS twenty-four Beagles were enrolled and performed BCS evaluation. In addition, the length of chest and abdominal girths were measured. In correlation analysis, the sizes of chest and abdominal girth were significantly correlated with BCS. Especially, the difference and ratio of the chest and abdominal length were highly correlated with the BCS. With that, we suggested that this simple measurement of chest and abdominal girths by a measuring tape would be an effective method to estimate BCS scores in dogs that helps non-professionals to manage their own dog’s nutritional condition by monitoring body fat accumulation condition.

Production of transgenic animals for studying specific gene has been limited due to a low efficiency, lack of skilled researchers and the need for expensive equipment. Currently, the boar spermatozoa as a vector to deliver exogenous DNA into the oocyte were used to improve the efficiency of transfection rate. In this study, we revealed that the optimal conditions for DNA uptake in spermatozoa by liposome were to 90 min of incubation, 17'C, 10' spermatozoa, 4 ng/ml of exogenous DNA and 0.5% (v/v) liposome, without damage to fertility. In addition, the developmental rate to the blastocyst stage of embryo in control group was significantly higher than those embryos with exogenous DNA and liposome, whereas there were no significant differences in embryo development between the liposome and type of DNA. The transfection rates of embryo using treated spermatozoa with both liposome and circular DNA were higher than those using linear DNA. These findings raise the possibility thattreated spermatozoa with liposome/DNA complexes could be used in in vitro fertilization, and the exogenous DNA transferred into the oocytes. Taken together, we demonstrated that liposome a vector for the uptake of exogenous DNA in boar spermatozoa could improve the efficiency of sperm-mediated gene transfer in creating transgenic pig and the other domestic transgenic animals.

국내에서 대표적으로 버려지는 폐벌목인 잣나무와 리기다소나무를 이용하여 고부가가치 제품으로 활용할 수 있는 활성탄 개발을 위해 목탄 제조의 최적조건을 측정하였다. 폐벌목 활성탄 제조에 관한 연구는 저온열분해 공정에 의한 폐벌목의 목탄 제조공정과 화학적 활성화반응을 이용한 목탄의 활성탄 제조공정으로 나누어지며 본 논문은 저온열분해에 의한 폐벌목의 목탄 제조공정을 다루고 있다. 실험결과, 목탄 제조공정의 경우 150˚C에서 6시간 건조 후 500˚C에서 60분 동안 열분해 공정을 거쳐 생성된 목탄이 요오드 흡착력과 비표면적(BET) 등의 물성이 가장 우수하였으며 SEM 사진을 관찰한 결과 이 조건에서 세공이 발달함을 알 수 있었다. 일반적으로 잣나무를 이용하여 제조된 목탄의 물성치가 리기다소나무를 이용한 목탄보다 우수함을 알 수 있었다. 본 연구의 최적 실험조건에서 잣나무를 이용한 목탄의 경우 BET 값이 약 640 m²/g에 이르렀다.

Using a pinus koraiensis and pinus rigida which are normally being discarded in South Korea, the optimal condition of producing charcoals has been studied to develop activated carbons which can be recycled as a higher value-added product. A study on manufacture of activated carbons from a discarded timber consists of two processes, the production process of charcoals from a discarded timber by low temperature pyrolysis process and the production process of activated carbons from the charcoals by chemical activation reaction. This study deals with the production process of charcoals from a discarded timber by low temperature pyrolysis process. As a results of experiment, it was investigated that charcoals produced through drying at 150˚C for 6hr and pyrolysis process at 500˚C for 1hr had the highest values in physical properties such as iodine number and BET surface area. Furthermore, through observing SEM images, the maximum development of porosity had been founded in this condition. It was confirmed that values of physical properties on using a pinus koraiensis are superior to the ones when using a pinus rigida. When charcoals were produced from a pinus koraiensis in this condition, BET surface area was approx. 640 m²/g.

Extractions of Artemisia princeps Pampanini were obtained by using water and ethanol at different temperatures (60℃, 100℃) with or without ultrasonification process (40 ㎑). Yield of ultrasonificated extracts were about 20% higher than that of control group. Cytotoxicity of all conditions through adding 1.0 ㎎/㎖ was below 37%, and treated with ultrasonification group was lower than the other group, about 5~8%. 100℃ water extract with ultrasonification was higher anticancer activities as maximum 73% and higher selectivities at concentrations over 0.8㎎/㎖. The extracts treated with ultrasonification were higher anticancer activities than the control. Densitometric analysis of bcl-2 revealed that extracts of high anticancer activity had low density. This results suggest that expression of bcl-2 protein by adding of Artemisia princeps Pampanini extracts relative to taking cancer. To conclude, optimum condition for efficient extraction of Artemisia princeps Pampanini is using water with ultrasonification at over 60℃ below 100℃.

본 실험은 고온증기세척수의 분무가 돼지도체 표면 미생물수의 감소와 돈육품질에 미치는 영향에 대해 알아보고자 실시하였다. 처리전과 비교하여 처리후 복강쪽 및 체외표면에서 표면 미생물수는 감소하며, 분무온도가 증가할수록 총균수의 차이를 보여준다(P<0.05). 그러나 80℃ 이상의 온도 즉, 90℃의 고온증기 세척시 80℃의 분무온도와 비교하여 미생물수 감소 효과를 보이지 않은 것으로 미루어(P>0.05) 고온증기 세척수의 분무 온도는 80℃가 적당할 것으로 판단된다. 고온증기 세척수의 처리시간별 돼지도체 표면 미생물수의 변화는, 처리전과 비교하여 처리후 미생물수는 감소하였다(P<0.05). 그러나 복강쪽 및 체외표면 모두 20초의 분무시간에 비해 30초 및 60초 처리시 총균수 변화에 차이를 나타내지 않아 20초 세척시간이 효과적인 것으로 판단된다. 고온증기 세척수의 분무온도가 돈육질에 미치는 영향을 구명하기 위한 육질평가에서 80℃ 이상의 온도에서 등심과 뒷다리 모두 높은 명도 값이 나타났다(P<0.05). 근육의 pH와 보수력은 온도가 증가할수록 감소하며, 특히, pH와 근장단백질용해성은 80℃ 이상의 온도에서 유의적인(P<0.05)으로 낮게 나타나, 70℃의 고온증기 처리시 돈육질에 부정적인 영향을 미치지 않을 것으로 판단된다. 또한 세척시간에 따른 육색의 변화에서 등심과 뒷다리 모두 세척시간이 증가할수록 명도 값은 증가하며, 30초의 증기처리 이후 명도와 적색도에서 유의적인(P<0.05) 차이를 보여 빠른 pH 감소의 원인으로 돈육의 보수력이 나빠지는 것으로 나타났다. 따라서 70℃의 증기온도와 20초의 처리시간이 돼지도체 표면 미생물수를 감소시키며 돈육질에 부정적인 영향을 미치지 않는 최적 조건이라 판단된다.

The objective of this study was to determine the efficacy of different water temperatures and time of spray-washing on the removal of bacteria contamination from surface of pork carcass and to obtain better meat quality with high temperature stream between 60 to 90℃ for the time ranged from 10 to 60 sec. Results showed that total plate counts were significantly decreased with increasing steam temperature(P<0.05). Similar results were found with the spray time(P<0.05). The lightness(CIE L*) value was significantly increased in both loin and ham cuts over 80℃(P<0.05). Ultimate pH of muscle and water-holding capacity were decreased with increasing steam temperature(P<0.05). There was a significant difference in solubility of sarcoplasmic protein between 70℃ and 80℃ of the steam treatments with higher value at 70℃(P<0.05). Again, longer than 30 sec spray at 70℃ steam, the lightness value of pork was significantly increased(P<0.05), while pH and water-holding capacity of muscle were significantly decreased(P<0.05). Therefore, a desirable pork quality would be achieved with spray-steam washing at 70℃ for 20 sec on pork carcass.

This study was carried out to obtain the basic data on artificial culture of Sparassis crispa. The mycelial growth and density were good in the PBA, PDA and PDM media, and especially prominent in the PBA medium. The optimum condition for the mycelial growth was 25℃ and pH 5.0, respectively. The carbon sources such as glucose, fructose, mannose, xylose(monosaccharide) and maltose(disaccharide) were favorable to mycelial growth of S crispa. The optimal concentration of glucose is 1.0∼1.5%. As nitrogen sources, threonine, peptone, glycine, glutamine and valine appeared to be favorable to the mycelial growth and density. The optimal concentration of peptone is 0.3%.

Recently, various efforts to make more speedy and precision machine tool to improve productivity and also various efforts to solve environmental problem are going on, so that dry cutting in manufacturing industry, which needs environmental conscious design and development of manufacturing technique, is becoming a very important assignment to solve. Because dry cutting does not use cutting fluid, we need other methods that can be used instead of cutting fluid, which does cooling, lubricating, chip washing, and anti-corrosion. Especially, because turning is a continuous work, the consideration of tool life and surface roughness due to continuous heat and poor lubrication is important. The purposes of this paper are the consideration of how well the compressed air can work instead of cutting fluid, and also the development of the method to select the optimum machining condition by the minimum numbers of experiments through the Taguchi method.

Mahalanobis Taguchi-System (MTS) has been used in different diagnostic applications to make quantitative decisions by constructing a multivariate system using data analytic methods without any assumption regarding statistical distribution. MTS performs Taguchi's fractional factorial design based on the Mahahlanobis distance as a performance metric. In this study, MTS used for analyzing automotive ride satisfaction, which measured as a CSR(Customer Satisfaction Rating). The automobile which has a good CSR score treated as a normal group for constructing Mahalanobis space. The results of this research show that two attribute (Impact Hardness and Memory Shake) have a minus gain value and can be removed from further analysis. With the linear regression model, the difference of CSR between using all 6 attributes and just using significant 4 attributes compared.

The purpose of this paper is to provide the optimal grinding conditions of metal components of a spectacles. The main elements of grinding conditions are composed of grain size, grade, structure, grinding wheel velocity and shifting components velocity. The conditions are co- related and influenced at each other. The precision of grinding surface was controled the each grinding conditions, mutual relations and reciprocal actions. It was studied the co-relations of grinding conditions those machining time-grain size-roughness, grade-roughness, machining time-characteristics of structure- roughness, number of production-roughnessgrinding wheel velocity, number of production-shifting velocity-grinding wheel velocity. The optimal grinding working condition satisfied the demanded surface accuracy 0.5 ~ 1.5μm. Based on these results, the optimal conditions were that the grain size was 60, the grade was middle of HIJK and LMNO, wheel velocity was 25 m/sec, shifting velocity was 15 m/min.

The results of examining selection of optimal mycelial growth condition excellent strain for determining the condition of Pleurotus cornucopiae are as follows. 1) Mycelial growth and density of P. cornucopiae were the highest in the medium of MCM(87.8mm/10d) followed by the order of PDA, YM, MEA and Czapek. 2) Optimal temperature for the mycelial growth and density of P. cornucopiae was shown to be 25℃, but the hyphae were dead at 5℃. The mycelial growth and density of KNAC2003 strain was the highest at 25℃(87.8mm/10d) followed by the order of 25, 30, 20, 35, 10 and 5℃. 3) Optimal pH for the mycelial growth and density was revealed to be 6.0(88.3mm/10d), but the mycelial growth and density were shown to be retarded in above or below pH 6.0.

As the capacity of renewable power generation facilities rapidly increases, the variability of electric power system and gas turbine power generation is also increasing. Therefore, problems may occur that require urgent repair while the gas turbine rotor is stopped. When the gas turbine rotor turning is stopped and then restarted, if the turning period is not appropriate, severe vibration may occur due to rotor bending. As a result of the experiment, it was confirmed that normal operation is possible when the gap data measured at the start of rotor turning after maintenance work is similar to the existing value. And the vibration value at the start of rotor turning was lower as the rotor temperature was lower or the stop period was shorter.

Miscanthus is one of major crop for bio-energy, its biomass is usually more than those of other crops and culture condition is suitable for Korean climate. Miscanthus’s potential biomass will be 42ton / ha, which around tow times more than one of switchgrass. In this study, we were focused on optimal condition of pretreatment for lignocellulosic biomass in miscanthus by using ammonia. Materials were analyzed to NREL standard quantification of cellulosic biomass. Miscanthus consists of 35~42% of cellulose, 22~25% of hemicellulose and 23~25% of lignin. To find of optimal conditions for effective fractionation of carbohydrates and their conversion process into sugars were checked; hydrolyzing the sample with 10~20% aqueous ammonia at 150~190 for 20~60 minutes. For effective hydrolysis, an oilbath with high temperature control was used and sample was hydrolyzed by using 15mL cylinder type reactor. The best concentration of samples for the reaction was 7.5%. To improve of ethanol conversion ratio, economical and effective pretreatment conditions have to be developed such as combination of aqueous ammonia and diluted acid treatment. Fermentable concentration of sample and optimal culture medium should be considered.

Biomass-derived tar and waxy compounds have a highly negative effect on the separation and purification of paclitaxel and should be removed prior to final purification. Adsorbent treatment is a simple, efficient method for removal of tar and waxy compounds from plant cell cultures. In this study, we optimized the important process parameters (adsorbent type, solvent type, adsorption time and temperature) of adsorbent treatment to remove the tar and waxy compounds in a pre-purification step. Using the adsorbents, sylopute, active clay, HP-20, and silica, we determined differences in the effectiveness of the adsorbent treatment according to changes in the solvent type, adsorption time and temperature. This effect could also be confirmed by HPLC analysis of the adsorbent after treatment as well as by TGA of the organic matter bonded to the adsorbent. In adsorbent treatment step, the purity seemed to show a small improvement but this treatment had a significant effect on convenient and feasibility of following steps by removing of tar and waxy compounds.