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        검색결과 254

        21.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cordyceps militaris, a well-known traditional Chinese medicine, has multiple health-promoting effects. It is used as a herbal remedy and health food in Asian countries. Cultured mycelia are often used as a substitute for natural C. militaris. In the present study, the mycelia and fruiting bodies of artificially cultured C. militaris were analyzed using a metabolomics approach. The protein and crude fat contents of the mycelia were substantially higher than those of the fruiting bodies. The top three abundant amino acids in the mycelia were proline (3.9 g/100 g), aspartic acid (2.9 g/100 g), and glutamic acid (2.7 g/100 g). The carbohydrate content was similar in the fruiting bodies and mycelia. Analysis revealed that both the fruiting bodies and mycelia are rich in phenolic compounds and exhibit antioxidant activity. Further, six metabolites were significantly different between the mycelia and fruiting bodies. The levels of Ca, glucose, Mg, and Se were higher in the mycelia than in the fruiting bodies. In contrast, mannitol and Zn were more abundant in the fruiting bodies. The current study provides a comprehensive metabolic profile of the mycelia and fruiting bodies of artificially cultured C. militaris. Such an exercise is potentially important for understanding the metabolism of C. militaris and facilitating the use of cultured mycelia as a supplement to C. militaris fruiting bodies in traditional Chinese medicine.
        4,000원
        22.
        2022.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We introduce the Transformable Reflective Telescope (TRT) kit that applies an aluminum profile as a base plate for precise, stable, and lightweight optical system. It has been utilized for optical surface measurements, developing alignment and baffle systems, observing celestial objects, and various educational purposes through Research & Education projects. We upgraded the TRT kit using the aluminum profile and truss and isogrid structures for a high-end optical test device that can be used for prototyping of precision telescopes or satellite optical systems. Thanks to the substantial aluminum profile and lightweight design, mechanical deformation by self-weight is reduced to maximum 67.5 μm, which is an acceptable misalignment error compared to its tolerance limits. From the analysis results of non-linear vibration simulations, we have verified that the kit survives in harsh vibration environments. The primary mirror and secondary mirror modules are precisely aligned within 50 μm positioning error using the high accuracy surface finished aluminum profile and optomechanical parts. The cross laser module helps to align the secondary mirror to fine-tune the optical system. The TRT kit with the precision aluminum mirror guarantees high quality optical performance of 5.53 μm Full Width at Half Maximum (FWHM) at the field center.
        4,300원
        23.
        2022.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this experiment, the error according to the measurement method was analyzed for the length, angle, radius of curvature, and diameter of the measurement system analysis using a profile projector device used in the field. One-way analysis was performed on each data tested 30 times using a statistical technique. Through the experiment, it was found that an error occurred in each data when measuring the angle according to the measurement method, and the null hypothesis that no error occurred when measuring the length, inside dia and radius was established.
        4,000원
        24.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : For high driving performance and service life of cement concrete pavement, construction quality must be secured. The construction quality is to be measured after pavement construction, but in this case, it is difficult to improve construction quality. Therefore, it is necessary to develop a method for measuring and correcting the profile of the pavement and subbase so that the construction quality can be monitored immediately after construction. METHODS : The device that can measure the construction quality of cement concrete pavement has been developed. Through the experiment simulating the field situation, the profile of the pavement and subbase was measured and calibration method was developed. RESULTS : In the measured profile, an outlier by the sensor and noise by the sensor and vibration were measured, and a step-like profile was measured differently from the acture one. To remove outliers, the boxplot outlier removal method was applied by overlapping each data group. The noise were removed by a low pass filtering. And, it was calibrated to a profile similar to the acture one through the sampling interval adjustment and the weighted moving average method. CONCLUSIONS : The method that can measure and calibrate the profile that is almost identical to the actual one has been developed. Accordingly, it is expected that the performance of the pavement can be improved by accurately monitoring the construction quality immediately after construction.
        4,200원
        25.
        2021.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Preparation of activated carbon from biomass residue with conventional steam activation was conducted to find the alternative raw materials for meeting the high demand for low-cost porous material in the desiccant application. In this study, activated carbons were produced from dead camphor leaves using two-step methods at different preparation temperatures. The characterization results revealed that the prepared activated carbons have a surface area of 700 m2/g, with 75% of microporosity. The water vapor sorption study reported that the water uptake of camphor leaf-based activated carbons was strongly affected by the pore properties of the materials. Moreover, from the water adsorption kinetics, it was observed that the rate constant of adsorption was varied at each relative pressure, which can be assumed that the water adsorption mechanism is different at each relative pressure. From these results, it was revealed that the prepared camphor leaf-based activated carbons have a promising ability to adsorb water vapor from humid air.
        4,300원
        29.
        2021.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, the effect of the turbulence intensity in across-wind direction on the wind load in CFD(Computational fluid dynamics) simulation was analyzed. ‘Ansys fluent’ software was used for CFD simulation. And the fluctuating wind speed applied to the simulation was generated according to Korean Design Standard and Von Karman wind turbulence model. The turbulence intensity in across-wind direction for simulation was applied from 0 to 100% of the turbulence intensity in along-wind direction. The analysis results showed that the turbulence intensity in across-wind direction had a particularly great effect on the wind load in across-wind direction.
        4,000원
        30.
        2021.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this work, the results obtained from the simulation of sedimentation of an elliptical cylinder in a viscous fluid are presented. The fluid flow velocity and pressure fields are evaluated by the famous lattice Boltzmann method (LBM). A smoothed profile method (SPM) is considered to enforce the no-slip boundary condition at the curved boundaries of the elliptical cylinder. The coupling between LBM LBM: Lattice Boltzmann Method and SPM SPM: Smoothed Profile Method is done by adding a hydrodynamic force term to the discretized version of the lattice Boltzmann equation. At first, the developed numerical code is validated by applying it to the unbounded laminar flow over an elliptical cylinder for different values of Reynolds number, Re. Later, simulations are carried out for sedimentation of an elliptical particle in a closed enclosure by considering different values for Re defined by terminal settling velocity of the cylinder. The robustness and accuracy of present simulation technique is assessed by comparing the particle trajectories and orientations obtained at different Re with the results from the existing literature. It is observed that, over a period of time, the particle attains steady state constant velocity and sediments horizontally when Re is low (Re=1.9) and moderate (Re=12.6). Whereas, an oscillating pattern for the sedimentation velocity is observed when Re is 32.9.
        4,000원
        31.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Spermatogonial stem cells are self-renewal and differentiate into sperm in post-pubertal mammals. There exists a balance between the self-renewal and differentiation in the testes. Spermatogonial stem cells make up only 0.03% of testicular cells in adult mice. These cells maintain sperm production by differentiating after puberty. Therefore, analyzing the expression of genes associated with spermatogenesis is critical for understanding differentiation. The present study aimed to establish the postnatal period of cells in relation to spermatogenesis. To study the expression of differentiated and undifferentiated marker genes in enriched spermatogonial stem cells, in vitro culture was performed and cells from pup (6–8-day-old) and adult (4-months-old) testicular tissues were isolated. As a result, undifferentiated genes, Pax7, Plzf, GFRa1, Etv5 and Bcl6b , were highly increased in cultured spermaotogonial stem cells compared with pup and adult testicular cells. On the other hands, differentiated gene, c-kit was highly increased in adult testicular cells, Also Stra8 gene was highly increased in pup and adult testicular cells. This study provides a better understanding of spermatogenesis-associated gene expression during postnatal periods.
        4,000원
        32.
        2020.12 구독 인증기관 무료, 개인회원 유료
        Heat shock proteins (HSPs) are highly conserved cellular proteins that contribute to adaptive responses of organisms to a variety of stressors. In response to stressors, cellular levels of HSPs are increased and play critical roles in protein stability, folding and molecular trafficking. The mRNA expression pattern of two well-known heat shock protein transcripts, HSP70 and HSP90 were studied in two tissues of nerve ganglia, cerebral ganglion and pleuropedal ganglion of Pacific abalone (Haliotis discus hannai). It was observed that both HSP70 and HSP90 transcripts were upregulated under heat stress in both ganglion tissues. Expression level of HSP70 was found higher than HSP90 in both ganglia whereas cerebral ganglion showed higher expression than pleuropedal ganglion. The HSP70 and HSP90 showed higher expression at Day-1 after exposed to heat stress, later decreased at Day-3 and Day-7 onwards. The present result suggested that HSP70 and HSP90 synthesize in nerve ganglion tissues and may provide efficient protection from stress.
        4,000원
        33.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        지난 10년간 복원력 상실에 의한 어선의 해양사고가 지속해서 증가하고 있으며, 갑작스러운 강풍이 주요 원인으로 지적되고 있다. 이러한 강풍에도 견딜 수 있는 어선의 운동·조종성능을 확보하기 위해서는 정밀한 풍하중 예측 기법이 우선되어야 한다. 따라 서 본 연구에서는 전산유체역학 기법을 이용한 어선의 풍하중 평가기법을 개발하고자 한다. 특히, 고도 변화에 따라 풍속이 변화하는 계산환경을 모사하여 그 결과를 균일한 속도분포를 가정한 수치해석 결과와 비교 분석하고자 한다. 본 연구에서는 0-180°까지 15° 간격 으로 13개의 방향에 대해 풍하중을 계산하였으며, 계산에 사용된 메쉬 모델은 메쉬 의존성 시험을 수행하여 개발하였다. 전산수치해석은 RANS(Reynolds-averaged Navier-Stokes) 기반 상용 해석 Solver인 STAR-CCM+(Ver. 13.06)와 k-w 난류 모델을 이용하여 정상상태(Steady State) 유동해석을 수행하였다. 수치해석결과를 간략히 살펴보면 Surge, Sway 및 Heave에서 39.5 %, 41.6 % 및 46.1 % 풍하중이 감소하였으 며 Roll, Pitch 및 Yaw에서 48.2 %, 50.6 % 및 36.5 % 감소하였다. 결론적으로 본 연구에서는 고도에 따른 풍속 변화 모델을 통해 기존보 다 정밀한 수준의 풍하중 추정이 가능한 것을 확인하였으며, 그 결과가 선박의 풍하중 추정 평가기법 발전에 이바지하길 기대한다.
        4,000원
        34.
        2020.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to examine the effects of Atractylodes lancea (A.l.) in a dose-dependent manner on lipid levels and plasma glucose in diabetic rats induced with streptozotocin (STZ). The Sprague-Dawley rats were randomly classified into five groups: normal, STZ-control and three experimental groups [A.l.-1, diabetic treated with ethanolic extract of A.l. (1 g/kg b.w.), A.l.-2, diabetic administered with ethanolic extract of A.l. (2 g/kg b.w.), and A.l.-3, diabetic administered with ethanolic extract of A.l. (3 g/kg b.w.)]. The normal and STZ-control group were fed an AIN-93 diet and the three experimental groups were administered with A.l. extract at doses of 1, 2, and 3 g/kg b.w./day, respectively, for 14 days. The plasma glucose levels in all the experimental groups were significantly lower than the STZ-control group after 14 days of treatment. The total cholesterol of the A.l.-3 and triglyceride levels, atherogenic index (AI) of all three experimental groups were significantly lower than the STZ-control group. The ALT and AST activities at A.l.-2, A.l.-3 were significantly lower than the STZ-control group. This result that demonstrate the administration of Atractylodes lancea can reduce hyperglycemia and hyperlipidemia risk in diabetic rats.
        4,000원
        36.
        2020.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research confirmed the diversity and characterization of halophilic microorganisms isolated from the various solar salterns, collected on the inside and outside of the country. To isolate strains, the marine agar medium was basically used and cultivated at 37oC for several days aerobically. After single colony isolation, a totally of 230 pure colonies were isolated and phylogenetic analysis was carried out based on the result of 16S rDNA sequencing, indicating that isolated strains were divided into 4 phyla, 12 families, 27 genera and 64 species. Firmicutes phylum, the main phyletic group, comprised 89.6% with 3 families, 17 genera and 52 species of Bacillaceae, Staphylococcaceae and Carnobacteriaceae. To confirm whether isolated strain can produce industrially useful enzyme or not, amylase, lipase, and protease enzyme assays were performed individually, showing that 177 strains possessed at least one enzyme activity. Especially 17 strains showed all enzyme activity tested. This result indicated that isolated strains have shown the possibility of the industrial application. Therefore, this study has contributed to securing domestic genetic resources and the expansion of scientific knowledge of the halophilic microorganisms community in solar salterns.
        4,800원
        37.
        2020.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 정삼투 중공사막 모듈에서 중공사막의 가닥을 비틀어 배치하였을 때의 효과를 알아보기 위해 CFD 전산 유체 역학 프로그램을 통해 5개의 다른 각도로 비틀린 중공사막 모듈을 설계하고 시뮬레이션하여 비틀리지 않은 모듈과 비교하였다. 실험 결과, 중공사막이 비틀렸을 때, 모듈 내부의 유도 용액의 농도가 비틀리지 않을 때에 비해 고르게 분포하였 다. 모듈 입구의 압력은 중공사막의 비틀림과 관계없이 일정한 값을 보였지만 출구의 압력은 중공사막이 비틀린 정도가 커질 수록 증가하는 추세를 보였다. 출구의 압력이 높아짐에 따라 막 내부의 유체 속도가 감소하고 모듈 체류 시간이 증가하여 막 사이의 물질 교환이 원활하게 이루어질 것으로 예측된다. 이는 결과적으로 막이 비틀려 있을 때의 모듈 플럭스가 투과 수량 이 차지하는 비율이 그렇지 않을 때에 비해 2배 증가하였다.
        4,300원
        38.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        제2형 당뇨 마우스로 8주간 50%, 75% 강도의 유산소성 및 저항성 운동을 수행하여 항 당뇨 및 지질 개선에 미치는 영향을 비교 분석하였다. 39주령 C57BL/6 마우스 48마리를 일반식이정상군 (Normal, n=8)을 제외하고, Streptozotocin (STZ)으로 당뇨를 유발하여 제2형 당뇨군(DM, n=8), 제2형 당뇨+VO2max 50% 유산소운동군(DM50A, n=8), 제2형 당뇨+VO2max 75% 유산소운동군(DM75A, n=8), 제2형 당뇨+1RM 50% 저항운동군(DM50R, n=8), 그리고 제2형 당뇨+1RM 75% 저항운동군 (DM75R, n=8)으로 구분하였다. 유산소성 운동은 주 5일, 1일 40분씩 8주간 트레드밀 운동을 실시하였으며, DM50A군은 1~4주는 8m/min, 5~8주는 8~10m/min으로, DM75A군은 1~4주는 12m/min, 5~8주는 12~14m/min으로 점증하여 실시하였다. 저항성 운동은 주5일 8주간 사다리 저항운동을 실시하였으며, DM50R군은 1RM의 50%, DM75R군은 1RM의 75%로 운동 반복 사이 2분간의 휴식을 주어 총 8번의 Climbing을 실시하였다. 8주간의 운동 후 공복 혈당은 DM군에 비해 DM운동군에서 유의적으로 낮았으 며, 인슐린은 운동에 따른 유의한 차이가 없었으나, HOMA-IR은 DM군에 비해 DM운동군이 유의하게 낮은 것으로 나타났다. HbA1c는 DM군에 비해 DM50R 및 DM75R군이 유의하게 낮은 것으로 나타났다. 총콜레스테롤과 LDL-C는 DM운동군 간의 차이가 없었으나, HDL-C는 DM75A군이 가장 높은 수준으로 나타났고, 중성지방은 DM75R군이 가장 낮게 나타났다. 심혈관 위험 지수는 Normal군 및 DM75A군이 가장 낮게 나타났다. 따라서 T2DM 마우스에서 중강도의 저항성 운동은 혈당 및 인슐린 저항성 조절에 더 나은 개선을 보여주었으며, 중강도의 유산소성 운동은 HDL-C 수준 증가를 통한 심혈관 위험 지수를 감소 하는데 효과적이었다.
        4,200원
        39.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 한국산 재래종 메밀가루를 40%, 70% 에탄올(발효주정)로 각각 처리하여 메밀 추출물을 제조하였고 이를 동결건조한 다음 고지방식이에 혼합하여 흰쥐에게 섭취시킨 후 나타나는 식이성 고지혈증의 개선효과를 확인하고자 하였다. 실험군은 정상대조군(NC), 고지방대조군(HFC), 고지방-40%에 탄올메밀추출물군(HF-40), 고지방-70%에탄올메밀추출물군(HF- 70) 4군으로 나누어 4주간 실험식이로 사육하였으며 실험 결과는 다음과 같다. 1. 실험동물의 식이섭취량과 체중증가량 및 사료효율은 실험군들 간에 유의적 차이를 보이지 않았다. 2. 실험동물의 장기 중간무게를 비교한 결과 정상대조군에 비해 고지방대조군에서 유의적으로 높았고 고지방대조군에 비해 HF-70군은 유의적으로 낮았고 (p<0.05) 정상대조군도 비슷한 수준이었다. 3. 혈중 GOT, GPT 수치는 정상대조군이 가장 낮았고 고지방대조군이 가장 높았으며 HF-40군과 HF-70군은 고지방대조군보다 낮은 경향을 보였다. 혈당 농도는 전체 실험군 중에서 HF-70군이 가장 낮은 경향을 보였다. 4. 혈중 중성지질 농도는 정상대조군에 비해 고지방대조군이 가장 높았고 정상대조군과 고지방대조군에 비해 HF-40군 이 유의적으로 낮았으며(p<0.05) 혈중 유리지방산 농도는 실험군 간에 유의적인 차이를 보이지 않았다. 5. 혈중 콜레스테롤 농도는 정상대조군에 비해 고지방대조군에서 유의적으로 높았고(p<0.05) 고지방대조군과 비교했을 때 HF-70군에서 낮은 경향을 보였으며, 혈중 유리콜레스테롤 농도는 실험군 간에 유의적인 차이가 없었다. 혈중 콜레스테롤에스터 수치는 정상대조군이 71.6mg/dl로 유의적으로 가장 낮았고 고지방대조군의 125.0mg/dl와 비교하여 HF-40군, HF- 70군은 각각 116.9mg/dl, 88.5mg/dl로 유의적으로 낮았다 (p<0.05). 특히 HF-70군은 HF-40군에 비해서도 유의하게 낮은 것으로 나타났다. 6. 혈중 LDL-콜레스테롤은 정상대조군에 비해 고지방대조군이 유의적으로 높았으며 고지방대조군(130.6mg/dl)에 비해 HF-70군(85.1mg/dl)에서 유의적으로 낮았다(p<0.05). 7. 혈중 HDL-콜레스테롤은 정상대조군에 비해 고지방식이군들이 유의적으로 낮았으며(p<0.05) 고지방실험군들 간에는 유의적인 차이가 없었다. 그러나 HDL-콜레스테롤/총콜레스테 롤의 비율은 정상대조군에 비해 고지방대조군이 유의적으로 낮았고 고지방대조군에 비해 HF-70군이 유의적으로 높았다 (p<0.05). 8. 동맥경화지수는 정상대조군이 가장 낮았으며 고지방대조군이 정상대조군에 비해 유의적으로 높았고 고지방대조군에 비해 HF-70군은 유의적으로 낮았다 (p<0.05). 본 실험에서 고지방식이를 섭취한 쥐의 이상지질혈증은 메밀 에탄올추출물에 의해 개선되었으며 40% 에탄올 메밀추출 물보다 70% 에탄올 메밀추출물에서 더욱 많이 개선되는 것으로 확인되었다.
        4,000원
        40.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hypoxia is one of the most common features of cancer. It is also associated with cancer progression and the acquisition of aggressiveness, which includes invasion and metastasis. Oral squamous cell carcinoma accounts for 90% of all oral cancers, and its 5-year survival rate is about 50%. Despite various attempts and trials, its prognosis has not improved. Among numerous adverse prognostic factors, hypoxia is suspected as one of the most important factors, as it increases the aggressiveness of oral cancer cells. We attempted to observe the effect of hypoxia on the expression of epithelial-mesenchymal transition markers in oral cancer cells. We analyzed and compared both the mRNA and protein expression levels of epithelial-mesenchymal markers using qRT-PCR and western blotting in both normoxic and hypoxic YD10B oral squamous cell carcinoma cells. Eighty-six genes were analyzed through real-time PCR using commercial microarray plates, performed in triplicate. Among the 86 genes, the expression of 24 were increased (≥ 2 fold) by hypoxia, while that of three genes was decreased (≥ 2 fold). Hypoxia significantly affects epithelial-mesenchymal transition-related genes. Further studies on the regulation of these genes may help to develop more efficient therapeutic modalities for oral cancer and to improve prognosis of oral cancer patients.
        4,000원
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