This study used optical and scanning electron microscopy to analyze the surface oxidation phenomenon that accompanies a γ'-precipitate free zone in a directional solidified CM247LC high temperature creep specimen. Surface oxidation occurs on nickel-based superalloy gas turbine blades due to high temperature during use. Among the superalloy components, Al and Cr are greatly affected by diffusion and movement, and Al is a major component of the surface oxidation products. This out-diffusion of Al was accompanied by γ' (Ni3Al) deficiency in the matrix, and formed a γ'-precipitate free zone at the boundary of the surface oxide layer. Among the components of CM247LC, Cr and Al related to surface oxidation consist of 8 % and 5.6 %, respectively. When Al, the main component of the γ' precipitation phase, diffused out to the surface, a high content of Cr was observed in these PFZs. This is because the PFZ is made of a high Cr γ phase. Surface oxidation of DS CM247LC was observed in high temperature creep specimens, and γ'-rafting occurred due to stress applied to the creep specimens. However, the stress states applied to the grip and gauge length of the creep specimen were different, and accordingly, different γ'-rafting patterns were observed. Such surface oxidation and PFZ and γ'-rafting are shown to affect CM247LC creep lifetime. Mapping the microstructure and composition of major components such as Al and Cr and their role in surface oxidation, revealed in this study, will be utilized in the development of alloys to improve creep life.

High-temperature oxidation of a Ni-based superalloy was analyzed with samples taken from gas turbine blades, where the samples were heat-treated and thermally exposed. The effect of Cr/Ti/Al elements in the alloy on high temperature oxidation was investigated using an optical microscope, SEM/EDS, and TEM. A high-Cr/high-Ti oxide layer was formed on the blade surface under the heat-treated state considered to be the initial stage of high-temperature oxidation. In addition, a PFZ (γ’ precipitate free zone) accompanied by Cr carbide of Cr23C6 and high Cr-Co phase as a kind of TCP precipitation was formed under the surface layer. Pits of several μm depth containing high-Al content oxide was observed at the boundary between the oxide layer and PFZ. However, high temperature oxidation formed on the thermally exposed blade surface consisted of the following steps: ① Ti-oxide formation in the center of the oxide layer, ② Cr-oxide formation surrounding the inner oxide layer, and ③ Al-oxide formation in the pits directly under the Cr oxide layer. It is estimated that the Cr content of Ni-based superalloys improves the oxidation resistance of the alloy by forming dense oxide layer, but produced the σ or μ phase of TCP precipitation with the high-Cr component resulting in material brittleness.

In this study, defects generated in the YSZ coating layer of the IN738LC turbine blade are investigated using an optical microscope and SEM/EDS. The blade YSZ coating layer is composed of a Y-Zr component top coat layer and a Co component bond coat layer. A large amount of Cr/Ni component that diffused from the base is also measured in the bond coat. The blade hot corrosion is concentrated on the surface of the concave part, accompanied by separation of the coating layer due to the concentration of combustion gas collisions here. In the top coating layer of the blade, cracks occur in the vertical and horizontal directions, along with pits in the top coating layer. Combustion gas components such as Na and S are contained inside the pits and cracks, so it is considered that the pits/cracks are caused by the corrosion of the combustion gases. Also, a thermally grown oxide (TGO) layer of several μm thick composed of Al oxide is observed between the top coat and the bond coat, and a similar inner TGO with a thickness of several μm is also observed between the bond coat and the matrix. A PFZ (precipitate free zone) deficient in γ' (Ni3Al) forms as a band around the TGO, in which the Al component is integrated. Although TGO can resist high temperature corrosion of the top coat, it should also be considered that if its shape is irregular and contains pore defects, it may degrade the blade high temperature creep properties. Compositional and microstructural analysis results for hightemperature corrosion and TGO defects in the blade coating layer used at high temperatures are expected to be applied to sound YSZ coating and blade design technology.

Microbiologically Influenced Corrosion (MIC) occurring in underground buried pipes of API 5L X65 steel was investigated. MIC is a corrosion phenomenon caused by microorganisms in soil; it affects steel materials in wet atmosphere. The microstructure and mechanical properties resulting from MIC were analyzed by OM, SEM/EDS, and mapping. Corrosion of pipe cross section was composed of ① surface film, ② iron oxide, and ③ surface/internal microbial corrosive by-product similar to surface corrosion pattern. The surface film is an area where concentrations of C/O components are on average 65 %/ 16 %; the main components of Fe Oxide were measured and found to be 48Fe-42O. The MIC area is divided into surface and inner areas, where high concentrations of N of 6 %/5 % are detected, respectively, in addition to the C/O component. The high concentration of C/O components observed on pipe surfaces and cross sections is considered to be MIC due to the various bacteria present. It is assumed that this is related to the heat-shrinkable sheet, which is a corrosion-resistant coating layer that becomes the MIC by-product component. The MIC generated on the pipe surface and cross section is inferred to have a high concentration of N components. High concentrations of N components occur frequently on surface and inner regions; these regions were investigated and Na/Mg/Ca basic substances were found to have accumulated as well. Therefore, it is presumed that the corrosion of buried pipes is due to the MIC of the NRB (nitrate reducing bacteria) reaction in the soil.

The effect of solidification rate on micro-segregation in investment casting of IN738LC superalloy was studied. In Ni-based superalloys, the micro-segregation of solute atoms is formed due to limited diffusion during cast and solidification. The microstructure of cast Ni-based superalloys is largely divided into dendrite core of initial solidification and interdendrite of final solidification. In particular, mosaic shaped eutectic γ/γ’ and carbides are formed in the interdendrite of the final solidification region in some cases. The micro-segregation phenomena formed in regions of dendrite core and interdendrite including eutectic γ/γ’ and carbides were analyzed using OM, SEM/EDS and micro Vickers hardness. As a result of analysis, the lack of (Cr, W) and the accumulation of Ti were measured in the eutectic γ/γ’, and the accumulation of (Cr, Mo) and the lack of Ti were measured in the interdendrite between dendrite and eutectic. Carbides formed in interdendritic region were composed of (Ti, W, Mo, C). The segregation applied to each microstructure is mainly due to the formation of γ’ with Ni3(Al,Ti) composition. The Ni accumulation accompanied by Cr depletion, and the Ti accumulated in the eutectic region as a γ’ forming elements. The Mo tends to diffuse out from the dendrite core to the interdendrite, and the W diffuse out from the interdendrite to the dendrite core. Therefore, the accumulation of Mo in the interdendrite and the deficiency of W occur in the eutectic region located in the interdendrite. Heat treatment makes the degree of the micro-segregation decrease due to the diffusion during solid solution. This study could be applied to the heat treatment technology for the micro-segregation control in cast Ni-based superalloys.

This study was conducted to evaluate the functionality of fermented black garlic extracts under various conditions. Black garlic powder was prepared by aging for 0~72 hours at 80℃ depending on relative humidity (RH). It showed the highest antioxidant effects among the samples; the total antioxidant activity of black garlic powders at RH 75%, 84%, and 90% for 72 hours was increased 31.9 times, 28.2 times, and 22.6 times compared with that of the fresh garlic powder, respectively. Also, the alliin content was gradually decreased. S-ally-L-cysteine and S-ethyl-cysteine levels were increased; the highest values were 495.9 μg/g and 1,769.7 μg/g after aging for 72 hours at RH 75%. Aspartate transaminase (AST) and alanine transaminase (ALT) levels were increased following high fat diet feeding, but the rise was obviously reduced by administration of black garlic extract. The total cholesterol, LDL/VLDL-cholesterol, and triglyceride contents in serum were significantly lower in methionine and choline deficient (MCD) diet treatment groups than in the positive control group. The concentration was increased following the intake of black garlic and fermented black garlic extracts. Therefore, black garlic extracts could be an ideal material as a dietary supplement in healthy functional foods to improve the effects on fatty liver.

The purpose of this study was to establish valerenic acid as a marker compound for the standardization of ethanol extract of Valerinan officinalis (valerian) root as a functional health food. We established valerenic acid as a marker compound using HPLC. HPLC was used to quantify the marker compound in the valerian extract after validation of methods with linearity, accuracy, and precision. The specificity for retention time was met by comparative analysis of the valerian extract and standard compound using HPLC. The method showed high linearity of the calibration curve with a coefficient of correlation (R2) of 0.9999. The limit of quantification (LOQ) was 10 μg/mL. The accuracy of measurement was 99.88~ 00.68% and the relative standard deviation (RSD) value was 0.59%. In addition, our analytical method yielded a 29% mean content of valerenic acid in the valerian ethanol extract. These results indicate that the established HPLC method facilitated the determination of marker compounds in the valerian extract for the standardization of health functional foods. Key words: Valerinan officinalis, valerenic acid, HPLC, validation, functional health food

The purpose of this study was that the optimal hydrolysis conditions of endo- and exo-type enzymes were selected to utilize organic cheese byproducts. Optimal substrate concentration and optimum enzyme ratio were measured by using 4 kinds of endo-type enzymes (alcalase, neutrase, protamex, and foodpro alkaline protease) and two exo-type enzymes (flavourzyme and prozyme 2000P) for whey protein hydrolysis were analyzed using liquid chromatography. As a result, the optimal endo-type enzyme through the first enzyme reaction was selected as alcalse, and as a result of the secondary enzyme reaction, flavourzme was selected as the Exo type enzyme. The concentration of whey protein substrate for optimal primary and secondary enzyme reactions was 10%. In addition, the optimum ratio of enzyme was 0.5% of alcalase and 0.2% of flavourzyme, which showed low molecular weight chromatography pattern compared to 2% of alcalase and 1% of flavourzyme hydrolyzate. Therefore, hydrolyzing the endo-type enzyme alcalase at a concentration of 0.5% for 10 hours and then hydrolyzing the exo-type enzyme flavouryme at a concentration of 0.2% for 4 hours was considered to be the optimum condition.

In this study, we optimized the coffee extraction conditions for instant coffee production in two stage percolators, which is the most common coffee extractor for instant coffee production. A central composite design was used to build mathematical model equations for response surface methodology (RSM). In these equations, the yield and overall acceptability of the coffee extracts were expressed as second-order functions of three factors, the feed water temperature, draw-off factor (DOF), and extraction time (cycle time). Based on the result of RSM, the optimum conditions were obtained with the use of desirability function approach (DFA) which find the best compromise area among multiple options. The optimum extraction conditions to maximize the yield and overall acceptability over 40% of yield were found with 163℃ of feed water temperature, 4.3 of DOF and 27 minutes of extraction time (cycle time). These results provide a basic data for the coffee extraction conditions for the competitive instant coffee in the industry.

Probiotic functional foods are known to have various functional effects such as intestinal regulation, modulation of immune system, reduction of allergies, and lowering of cholesterol. The purpose of this study was to select probiotic strain that is most suitable for freeze-dried coffee for the development of functional coffee products. The survival rate of probiotics, at drinking condition of coffee, at acid, at bile and after freeze-dried in coffee were measured on 1 strain isolated from commercial freeze-dried coffee, 8 strains used as fermented milk starter, 1 Bifidobacterium and 1 Bacillus coagulans. Bacillus coagulans showed the highest survival rate from 2.4×107 cfu/g to 2.0×107 cfu/g especially after freeze-drying. The results at drinking condition of coffee, at acid tolerance, at bile tolerance and at storage test showed significantly better survival rate of Bacillus coagulans than that of control (Lactobacillus casei). Especially, Bacillus coagulans showed 3.8-fold higher survival rate at acid tolerance (pH 1, 120 minutes) than control. Thus, the lactic acid-producing Bacillus coagulans is characterized as a probiotic strain suitable for functional coffee formulation and commercialization.

This study attempted to find an efficient method for the preparation of high-purity galactooligosaccharides (HP-GOS) using β-galactosidase and yeast fermentation. GOS prepared using Lactozym 3000L showed the greatest enhancement in total GOS of the six β-galatosidases tested. GOS alone achieved 51% conversion of initial lactose. GOS production was enhanced by fermentation with commercial yeast (Saccharomyces cerevisiae); its concentration reached 71% after 36h fermentation with 8% yeast. Component sugar analysis with HPLC indicated that HP-GOS fermented with S. cerevisiae showed significantly increased levels of 4’/6’-galactosyllactose and total GOS as well as a significantly decreased glucose level. HP-GOS facilitated the growth of Lactobacillus sp. (L. acidophilus and L. casei) and Bifidobacterium sp. (B. longum and B. bifidum). In sum, high-purity GOS has been successfully produced through both an enzymatic process and yeast fermentation. GOS encourages the growth of bacteria such as Lactobacillus and Bifidobacterium that may be beneficial to human gastrointestinal health.

Probiotics is known improve the microenvironment of colon; however, the metagenomic DNA study of its lactic acid bacteria in constipation induced by loperamide is not clearly understood. In the present study, we investigated the reduction of the lactic acid bacteria in case of constipation, in normal and loperamide-induced rat. Lactic acid powder (lactic acid bacteria 19) was prepared from Chong Kun Dang Pharmaceutical Corporation. After 2 weeks of oral administration, the group treated with the higher concentration of lactic acid bacteria (109 CFU/mL per kg of body weight) following loperamide treatment was the most effective in increasing number, weight, and water content of feces. A similar but significant increase was found in the group treated with lower concentration of lactic acid bacteria (107 CFU/mL per kg of body weight) after loperamide treatment. The concentrations of acetic acid and propionic acid in feces in the loperamide-induced rat with high concentration lactic acid, were significantly higher than that of others. Furthermore, gastrointestinal transit ratio as well as the length and area of intestinal mucosa were significantly increased after treatment with lactic acid bacteria in loperamideinduced rat. Metagenomics DNA analysis indicated that the microorganism homology in cecum was similar between the groups of normal (NOR) and HIG. Our results show that lactic acid bacteria were effective in improving the constipation.

This study was designed to investigate the effects of Korean Lycii fructus water extract in Al (Aluminum) administered rats. Forty-eight male Sprague-Dawley rats were divided into six groups: Control group, water extract group with 3% Lycii fructus, 1000 and 2000 ppm of Al groups, and 1000 and 2000 ppm of Al with 3% Lycii fructus water extract group. The Al content of rat tissue in the Al administered group was lower than that in rat tissue in the Al with 3% Lycii fructus water extract group. Plasma levels of renin and aldosterone activity was higher in the Al administration group, compared with the 3% Lycii fructus water extract group and Al administered group. Aspartate amino transaminase and alanine amino transaminase activities were elevated in the Al administered group and lower in the 3% Lycii fructus water extract group. Lactate dehydrogenase was lower in the 3% Lycii fructus water extract Al group than in the Al group. Choline acetyltransferase was higher in the 3% Lycii fructus water extract Al group than in the Al group.

대두(Glycin max Merrill) 배아의 기능적 활성을 조사하기 위하여 대두를 발아시켜 만든 배아(soybean sprout)을 시료로 하여 0.75% 콜레스테롤 첨가식이로 유발된 고지혈증 Sprague Dawley계 수컷의 흰쥐에 대두 배아의 유기용매 추출물을 급여시킨 후 혈청의 지질 개선효과를 알아보기 위하여 4주간 동안 대두 배아를 섭취시켰다. 식이 급여가 대조군의 체중 및 장기 무게에 미치는 영향은 거의 찾아볼 수 없었으며 혈청 총 콜레스테롤 및 LDL-콜레스테롤의 농도는 대조군에 비하여 낮았고. 콜레스테롤 식이군에 비하여 콜레스테롤 식이와 대두 배아 메탄을 추출물의 혼합투여시 낮게 나타났다. 총 콜레스테롤에 대한 HDL-콜레스테롤의 비는 대두 배아 추출물 급여군이 높게 나타났으며, 동맥경화 지수는 고콜레스테롤 식이군에 비하여 대두 배아 추출물이 낮았다. 또한 혈청중의 유리콜레스테롤 및 고콜레스테롤 에스테르의 농도는 고콜레스테롤 식이군에 비해 대두 배아의 혼합 급여군이 감소하였고, 인지질의 농도도 콜레스테롤 식이군 보다 콜레스테롤 식이와 대두 배아 급여군이 낮은 경향을 나타내었다.

오이, 마늘, 생강, 감자 및 무의 압추특성을 규명하기 위하여 식품물성 측정기로 압축힘, 거리 및 시간을 측정하고 이들의 상관관계를 살펴 보았다. 힘-거리 및 거리-시간 곡선은 비교적 간단한 형태를 나타냈고 변곡 점들이 잘 나타나지 않았다. 파괴점까지의 시간은 감자가 압축속도 60mm/min에서 11.79, 압축속도 120mm/min에서 6.16초로 가장 길었다. 마늘은 각각 9.65 및 4.55초로 적게 소요되었는데 이는 시료의 압축강도에 따른 차이점 때문으로 생각된다. 파괴힘은 무와 감자는 압축속도별로 16.64∼20.00N으로 가장 컸으며, 파괴시에 시료는 탐침밑에 뭉개어지는 거동을 보았다. 압축시험시 파괴점 까지의 힘-시간과 거리-시간에 대한 회귀분석 결과 상관계수 값이 0.96이상이었으며, 시료간의 차이는 작았다. 힘-거리 곡선의 기울기는 오이와 마늘이 1.772∼3.385로 가장 컸으며, 감가가 각각 1.743 및 3.338로 작았으며, 거리-시간 곡선의 기울기와는 반비례 관계를 나타냈다.

지금까지 많은 연구가 되어 있지 않던 Bacillus thuringiensis serover. darmstadiensis의 내독소를 Rengorafin-76 단계적 기울기 원심분리로 분리하여 전자 현미경으로 관찰하여 이중피라미드 구조를 가진 독소 단백질을 확인하였으며 B. thuringiensis serover. kurstaki HD1의 독소 생성유전자와 B. thuringiensis serovar. darmsladiensis의 유전자가 유사성이 있다는 보고를 근거로 하여 B. thuringiensis serovar. HD1의 독소생성유전자를 가진 프로브(pUYBT 9044)로 이용하여 colony hybridization 및 southern hybridization한 결과 2.6Kb EcoRI 단편 및 Southern hybridizationg한 결과 2.6Kb EcoRI 단편 및 3.6Kb HindⅢ 단편을 선발할 수 있었다. 이들 단편들은 B. thuringiensis serovar.kurstaki HD1 독소 유전자와 hybridization시 유사성이 있었다. 특히 3.5Kb HindⅢ 단편은 2.6Kb EcoRI 단편에 클로닝되어 있는 1.8Kb의 HD1 독소유전자와 유사성이 있는 부분을 공유하고 있었으며 1.0Kb정도의 EcoRI-HindⅢ 부분이 더 삽입한 것을 알 수 있었다.

건강한 남녀노인 244명을 대상으로 영양소섭취 실태 및 이에 영향을 미치는 요인들을 분석한 결과는 다음과 같았다. 남자노인들은 여자노인들에 비해 사회경제상태가 유의적으로 높았다. 사회경제상태는 남자노인의 영양소 섭취에는 큰 영향을 미치치 않았으나. 여자노인은 단백질과 칼슘, 철분, 나이아신 및 섬유소의 섭취량에 유의적인 영향을 주어 사회경제수준이 높을수록 이들의 섭취가 많았다. 영양소 섭취실태는 열량의 경우 남자노인이 평균 1, 528 kcal, 여자노인이 1, 292 kcal로 각각 권장량의 평균 79.1%와 65.5%를 차지하여 권장량에 부족되게 섭취하고 있었다. 권장량의 2/3이하로 섭취하여 문제가 되는 영양소는 남자노인은 칼슘과 비타민 A로 나타났으며 여자노인은 칼슘, 비타민 A 및 riboflavin로 여자노인들이 남자노인들 보다 식사의 질이 떨어지는 것으로 나타났다. 노인들의 연령에 따른 영양소 섭취량의 변화는 남녀노인에서 악간 다른 양상을 보여서 남자노인들은 75∼79세 까지는 섭취량이 어느 정도 유지되다가 80세 이후에 영양 섭취의 감소가 나타났으나, 여자노인은 이러한 섭취량의 감소현상이 더 빨리 나타나서 75∼79세의 나이 단계부터 영양소 섭취량의 급격한 감소가 나타났다. 노인들의 영양소 섭취에 영향을 미치는 요인으로는 나이가 가장 큰 영향을 미쳐서 나이가 증가함에 따라 모든 영양소의 섭취량이 저하되었으며, 남자노인의 경우는 신장이 여자노인의 경우는 사회경제상태와 체중, BMI가 영양소의 섭취량에 영향을 미치는 것으로 나타났다.

본 연구에서는 락툴로스(lactulose) 51.67%와 갈락토올리고당(galactooligo saccharides) 15.8%로 이루어진 듀올리고(DuOligo)의 섭취를 통하여 피부개선 효능을 조사하였다. 40 ∼ 60 대의 건강한 여성 37명 을 대상으로 대조군(덱스트린)과 실험군(듀올리고군)으로 나누어 각각 8주 동안 섭취 후, 수분보유량, 경표피수 분손실량, 멜라닌지수, 홍반지수와 주름지수를 측정하였다. 그 결과, 듀올리고 섭취 8주 후의 수분 보유량은 대 조군에 비하여 수분 보유량이 38.22% 유의적으로 증가하였다(p < 0.01). 대조군의 경피수분손실량은 8주후 3.39 g/h/m2로 감소한데 비하여 듀올리고군의 경피수분손실량은 8주후 5.32 g/h/m2 감소하였다. 대조군의 멜 라닌 지수는 시간에 따라 그 값이 유의적으로 증가하였으나, 듀올리고군의 멜라닌 지수는 시간에 따른 유의적 차이가 나타나지 않았다. 또한, 듀올리고군은 대조군에 비하여 주름의 총 넓이, 총 주름의 길이, 주름의 수 및 주름의 깊이가 확연하게 감소하였다(p < 0.05). 듀올리고의 피부개선 기능성 소재로서의 응용 가능성을 확인하 였다.