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        검색결과 10

        1.
        2018.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        자소엽(perilla frutescens)은 꿀풀과(Labiatae)에 속하며 널리 알려져 있는 약용 식물이다. 본 연구에서는 자소엽을 물, 열수, 초음파 추출 방법으로 추출하여 항산화 효과를 비교하고 가장 효과적인 추출 방법을 제시하고자 한다. 물, 열수, 초음파 처리를 통해 각각의 자소엽 추출물을 제조하였고, DPPH 라디 칼 소거능 및 총 페놀 함량을 통해 항산화 효과를 검증하고, 인간 간세포인 HepG2에 대한 세포 독성효과와 hydrogen peroxide (H2O2)로 유도된 산화적 스트레스로부터 간세포 보호효과를 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay로 확인하였다. 자소엽 초음파 추출물은 5000 ㎍/mL농도에서 69.07%의 DPPH 라디칼 소거능을 나타내며 물, 열수 추출물과 비교하여 우수한 항산화 효과를 나타내었다. 또한 총 페놀 함량 측정 결과 51.60±1.06 mg GAE/g extract 로서 물, 열수 추출물 보다 높은 총 페놀 함량을 확인하였다. 그러나 산화적 스트레스에 의한 세포 보호효과는 미비하였다. 본 연구를 통해 추출 방법에 따른 항산화 효과의 차이를 확인하였으며, 우수한 항산화 효과를 나타낸 자소엽 초음파 추출물을 이용하여 추가적인 연구가 필요할 것으로 사료된다.
        4,000원
        2.
        2016.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구의 목적은 가까운 미래의 선박운동정보를 이용하는 피드포워드 제어알고리즘과 FPSO 운동 수치 시뮬레이션 모델을 개발하고 시뮬레이션을 통하여 제어알고리즘의 성능을 검증하는 것이다. 본 논문에서는 조류, 바람, 파력 등의 환경하중에 의하여 발생한 선체운동의 미래 예측치를 활용한 피드포워드 제어력을 추가적으로 가지는 Dynamic Positioning System에 대하여 연구한다. 먼저, 조류력, 풍력 및 파력에 대한 수학모델을 선정하여 환경하중에서의 선체운동을 계산하고, 현재의 선체운동 값과 Brown 지수평활 예측모형을 활용하여 미래 선체운동 값을 예측하였다. 또한 위치 유지와 Heading angle 제어를 위한 제어력을 PID(Proportional-Integral-Derivative)이론을 이용하여 결정한 피드백 제어기와 미래 선체운동 값을 이용하여 결정한 피드포워드 제어기로 구성하였다. 그리고 각 Thruster에 요구되는 추력은 라그랑지승수법을 활용하여 분배하였다. 마지막으로 FPSO(Floating Production Storage and Offloading)의 운동과 Dynamic Positioning System에 대한 시뮬레이션 모델을 구축하여 선박의 위치 및 Heading angle 제어에 관한 시뮬레이션을 수행하여 제안하는 피드백 제어기와 피드포워드 제어기를 동시에 가지는 제어시스템의 성능을 평가하였다. 본 연구의 결과, 피드백 및 피드 포워드 제어기가 적용된 DPS 제어시스템이 기존의 피드백 제어기보다 위치유지 및 헤딩각 유지 능력에서 개선되었고 각 Thruster에 요구되는 평균 제어력 및 최대 제어력의 크기도 감소함을 보였다. 이에 따라 DPS에 요구되는 동력 감축과 Azimuth Thruster 용량의 감소로 인하여 비용 절감의 효과를 기대할 수 있다.
        4,000원
        3.
        2009.12 구독 인증기관 무료, 개인회원 유료
        This study investigated consumers’ recognition on shelf life of health functional foods to set up their rational expiration date. For this study 107 male and female adults aged 20 to 59 years were randomly selected as major consumers of health functional foods. And their data were analyzed with SPSS 17.0. The questionnaire included questions asking a consumer's recognition on the shelf life of health functional foods and how to treat health function food passing its shelf life. In this study, the consumers were found to pay attentions considerably to the shelf life. But most of them did not know an accurate meaning of the shelf life of health functional food and mistook it for expiry date. In addition, the consumers doubted safety of health functional foods passing the shelf life. Therefore, education for consumers about an accurate meaning of the shelf life was needed. The results of this study were considered to be helpful to set up a reasonable expiration date for health functional food.
        4,000원
        4.
        2009.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper the lifetime risk assessment of exposure to airborne volatile organic compounds (VOCs) in environmental atmosphere was carried out in one of the Korean industrial city, Gumi based on their measurements of VOCs at five representative outdoor monitoring sites. According to this study toluene, trichloroethylene, and dichloromethane are three main VOCs in Gumi. The carcinogenic risks 5the carcinogenic VOC are greater than the benchmark concentration (1.0E-6) in all five designated sites. Particularly, the Lifetime Cancer Risk in industrial complex 1 and 2 reached 9.64E-5 and 1.32E-4, respectively, both of which are far higher than the benchmark risks. The components of predominant risk in industrial areas are found as chloroform, benzene and trichloroethylene, while those of other sites are benzene and chloroform. It was estimated that the contributions of those componentsto cancer risk are not less than 90%. For non carcinogenic VOCs, the total hazard indices in 5 monitored sites are less than 1. The hazard index in industry complex No. 2 recorded the highest among 5 sites up to 0.663 due to the dominant contribution of 1, 2-dichloropropane by up to 50% (0.335). Based on this analysis, effective emission reduction for chloroform, benzene, trichloroethylene, and 1,2-dichloropropane will rapidly I the cancer risks and hazard indices in Gumi.
        4,000원
        5.
        2009.06 구독 인증기관 무료, 개인회원 유료
        This studyevaluates the effectiveness ofthe “ Seoul Sanitation Grading System Evaluation Index" devel0ped earlier and to analyze sanitation management practlces in restaurants in Seoul, Korea. The categories evaluated were the food management standard, facilities/equipment standard, and essential checking items specified in the law. These items were graded and classified into A (100~90), B (89~80), C (79~ 70) and Score (less than 69) based on the criteria set by the present researchers. We randomly selected 56 restaurants in five l0cal cities (Jung-gu, Seocho-gu, Jongno-gu, Songpa-gu and YIeongdeungpo-gu) and investigated each by actually visiting the site of business. The achievement rate for food management standard was 80.8%; as for the specific items in the category, it was the highest in food ingredients at 77.1 % and the lowest in food storage at 62.1 %. For the facilities/equipment standard, the achievement rate was 77.8%; as for the specific items in the category, it was the highest for vermin at 88 .1 % and the lowest for operation at 70.8%. The achievement rate for overall individual sanitary management was 70.7% and in the category, the lowest score was seen in hand washing at 57.1 %. The overall average score of sanitation management practices using the Seoul Sanitation Grading System Evaluation Index in restaurants in Seoul was 73.7, which fell into the C category. As for the number of restaurants in each grade category, there were 10 (17.9%) in each category of A (100~90), B (89~80) and C (79~70) with 30 (53.6%) scoring higher than 70, whereas those scoring less than 69 included 26 (46.4%). The average scores for those restaurants designated by local governments (exemplary restaurants, general restaurants, best Korean restaurants in Seoul) were not significantly diffierent; however, they were higher in franchises than those small restaurants ran by individuals.
        4,000원
        6.
        2018.03 KCI 등재 서비스 종료(열람 제한)
        In the present study, we employed Hershberger assay to determine possible androgenic or antiandrogenic activities of three di-2-ethylhexyl phthalate (DEHP) substitute candidates. The assay was carried out using immature castrated Sprague–Dawley male rats. After 7 days of the surgery, testosterone propionate (TP, 0.4 mg/kg/day) and test materials (low dose, 40 mg/kg/day; high dose, 400 mg/kg/day) were administered for 10 consecutive days by subcutaneous (s.c.) injection and oral gavage, respectively. Test materials were DEHP, 2-ethylhexyl oleate (IOO), 2-ethylhexyl stearate (IOS) and triethyl 2-acetylcitrate (ATEC). The rats were necropsied, and then the weights of five androgen-dependent tissues [ventral prostate, seminal vesicle, coagulating glands, levator ani-bulbocavernosus (LABC) muscle, paired Cowper’s glands, and glans penis] and four androgen-insensitive tissues (kidney, adrenal glands, spleen and liver) were measured. All test materials including DEHP did not exhibit any androgenic activity in the assay. On the contrary, antiandrogen-like activities were found in all test groups, and the order of the intensity was ATEC < DEHP < ISO < IOO in the five androgen-sensitive tissues. There was no statistical difference between low dose treatment and high dose treatment of all replacement candidate groups. In DEHP groups, high dose treatment exhibited significant weight gains in LABC and Glan Penis. There was no statistical difference in androgen-insensitive tissue measurements. Since the effects of ATEC treatment on the accessory sex organs were much less or not present at all when compared to those of DEHP, ATEC could be a strong candidate to replace DEHP. IOO treatment brought most severe weight reduction in all of androgen-sensitive tissues, so this material should be excluded for further screening of DEHP substitute selection.
        7.
        2017.12 KCI 등재 서비스 종료(열람 제한)
        Bisphenol-A(BPA) is a member of alkylphenol family, and shows adverse effects including reduced fertility, reproductive tract abnormalities, metabolic disorder, cancer induction, neurotoxicity and immunotoxicity. In the present study, we conducted Hershberger assay to evaluate whether the two candidates to replace BPA have androgenic or antiandrogenic activity. The assay was carried out using immature castrated Sprague–Dawley male rats. After 7 days of the surgery, testosterone propionate (TP, 0.4 mg/kg/day) and test materials (low dose, 40 mg/kg/day; high dose, 400 mg/kg/day) were administered for 10 consecutive days by subcutaneous (s.c.) injection and oral gavage, respectively. Test materials were BPA, isosorbide (ISO) and cyclohexanedimethanol (CHDM). The rats were necropsied, and then the weights of five androgen-dependent tissues [ventral prostate, seminal vesicle, levator ani-bulbocavernosus (LABC) muscle, paired Cowper’s glands, and glans penis] and three androgen-insensitive tissues (kidney, spleen and liver) were measured. All test materials including BPA did not exhibit any androgenic activity in the assay. On the contrary, antiandrogen-like activities were found in all test groups, and the order of the intensity was CHDM > BPA > ISO in the five androgen-sensitive tissues. There was no statistical difference between low dose treatment and high dose treatment of BPA group as well as ISO group. In CHDM group, high dose treatment exhibited most severe weight reduction in all measured tissues. There was no statistical difference in androgen-insensitive tissue measurements, except BPA groups. Since the effects of ISO treatment on the accessory sex organs were much less or not present at all when compared to those of BPA, ISO could be a strong candidate to replace BPA. CHDM treatment brought most severe weight reduction in all of androgen-sensitive tissues, so this material should be excluded for further screening of BPA substitute selection.
        8.
        2017.08 서비스 종료(열람 제한)
        Nonylphenols (NP) are used in manufacturing antioxidants and lubricating oil additives, which are considered to be as potent endocrine disruptor. The aim of this study was to examine the effects of NP on reproductive system in adult male mice. Mice were divided into 4 groups; (1) tap water (CON group), (2) 50 μg/L (NP50), (3) 500 μg/L (NP500) and (4) 5000 μg/L (NP5000) of NP via the drinking water for 4 weeks. Mice were sacrificed and the reproductive organ weights were measured. The caudal epididymal sperms were count to assess the toxicity on germ cells. Histopathological changes of tissues were observed by using hematoxylin/eosin staining. The weights of testis in NP5000 group were significantly lighter than those in CON group (104.9±2.9 mg vs 90.7±5.1 mg, p<0.05). And weights of epididymis significantly increased in NP500 group (44.2±2.6 mg vs 54.42±3.44 mg, p<0.05). As concentration of NP increased, the number of sperms significantly decreased (NP50 and NP500, p<0.01; NP5000, p<0.001). In histopathological analyses, the sperms in seminiferous tubules showed a concentration-dependent decrease in mice treated with NP. In epididymis, treatment with NP resulted in empty space and the reduced sperm numbers in dose-dependent manner. Our results confirmed the dose-dependent decrease in the number of sperm and histopathological abnormality of testis and epididymis in mice exposed from 50 μg/L to 5000 μg/L of NP for 4 weeks. The present study suggests that oral exposure of NP might have negative effects on reproductive function, particularly on germ cells, in adult male mice.
        9.
        2017.06 KCI 등재 서비스 종료(열람 제한)
        High-fructose corn syrup (HFCS) is widely used as sweetener, and its overconsumption is become a major health problem. In the present study, we used adult female rats and applied a 28 days HFCS feeding model to monitor the estrous cycle and changes in tissue weights and histology. Adult female rats were divided into three groups. Animals were fed with ad libitum normal chow and (1) 24 hours tap water (Control group), (2) 12 hours HFCS access during dark period and 12 hours tap water (12H group), and (3) 24 hours HFCS only access (24H group). Total exposure period was 28 days. There is no significant change in body weight between control and HFCS-fed animals. Both absolute and relative weights of ovary in 24H animals were significantly heavier than those in control or 12H animals. The absolute and relative weights of the kidney and liver in 24H groups were significantly heavier than those in control or 12H animals. The estrous cycles of the 24H animals were significantly longer. Histological analyses revealed that 24H ovaries were relatively bigger and possessed more corpus lutea than control ovaries. Uterine sections of 12H and 24H animals showed a well-developed stratum vasculare between inner and outer myometrial layers. The number of endometrial glands were decreased in 12H uteri, and recovered in 24H uteri compared to control. Numbers of convoluted tubule in distal region increased in 12H and 24H kidney samples. Liver specimens of 12H and 24H showed the increased number of fat containing vacuoles. In conclusion, our study demonstrated that HFCS treatment for 28 days could induce (1) changes in length of estrous cycle with extended estrous and diestrous stages, (2) altered ovarian and uterine histology, and (3) liver and renal lipid accumulation. These findings reveal the adverse effects of HFCS drinking on the reproductive function and lipid metabolism of female rats.
        10.
        2004.03 KCI 등재 서비스 종료(열람 제한)
        Column subtraction, originally proposed by Harche and Thompson(1994), is an exact method for solving large set covering, packing and partitioning problems. Since the constraint set of ship scheduling problem(SSP) have a special structure, most instances of SSP can be solved by LP relaxation This paper aim, at applying the column subtraction method to solve SSP which am not be solved by LP relaxation For remained instances of unsolvable ones, we subtract columns from the finale simplex table to get another integer solution in an iterative manner. Computational results having up to 10,000 0-1 variables show better performance of the column subtraction method solving the remained instances of SSP than complex branch and-bound algorithm by LINDO.