• 전력전자학회논문지
• /
• 제5권4호
• /
• pp.318-326
• /
• 2000

수전단의 관성이 0(수전단에 발전력이 전혀 없는 경우)인 약한 계통에서는 HVDC가 재기동과 무효전력 보상을 위해서 동기조상기의 존재는 필수적이다. 동기조상기와 주된 목적이 무효전력올 보상하는 것이지만 SVC나 STACON과 같은 무효전력 보상장치는 HVDC시스템을 재기동(HVDC에서는 Black-Start라 부른다)시킬 수 있는 능력을 가지고 있지 못하지 때문에 동기조상기가 발전력이 없는 약한 계통에서는 유일한 대안이다. 동기조상기는 발전기의 일종으로서 무효전력을 조정하는 여자 시스템의 종류에 따라 다른 특성을 가지고 있다. 정지형 여자 시스템은 속응성과 보수 유지의 간편성 때문에 많아 각광받고 있는 형태임에도 불구하고 시스템이 가지고 있는 본질적인 결함 때문에 약한 계통에 연결된 경우에는 짧은 문체점을 노출시키고 있다. 반면에 AC 회천형 여자 시스템은 속응성에 낮음에도 불구하고 여자기의 공급전원이 안정하다는 장점올 가지고 있다. 본 논문에서는 이러한 여자 시스템의 장단점을 분석하고 정지형 여자 시스템의 장점과 AC 회전형 여자 시스템의 장점올 결함한 새로운 여자 시스템올 제안하였다. 제안된 시스템은 HVDC 시스템에 연결된 경우에 좋은 제어 특성을 보여 주었으며 결과는 PSCAD/EMTDC를 이용하여 확인하였다.

• 대한수의학회지
• /
• 제14권2호
• /
• pp.159-171
• /
• 1974

Histological and histochemical studies were made on the lining epithelia of the various ducts in epidymis of the Rooster and absorptive function of the canal epithelial cells in the Rooster epididymis were also investigated after administration of India ink. The results obtained were summerized as follows; 1. Epihtelium lining the rate testis was mainaly composed of single later of cuboidal cells, and was partially composed of flattened squamous or low columnar cells. Efferential ductules were characterized by having many villous projections orrfolds which extened into the lumen, and were lined by stereociliated pseudostratified epithelium which consisted of manily ciliated columnar cells, a few scattered clear cells and basal cells. Connecting ductules were lined by ciliated pseudostriatified colummnar epithelium in which ciliated columnar cells, clear cells and basal cells were noted. Epididymal ducts were lined by pseudostratified epidhelium in which columnar and basal cells were noted. 2. PAS-granules, saliva resistant were noted mainly in the epithelial cells of efferential and connecting ductules. 3. Sudan black B stained heavily the granules in the epithelial cells of sufferential and connecting ductules. 4. The granules reactive to acid phosphatase most abundant in the epithelial cells of efferential ductules and were lesser amount in the epithelial cells of connecting ductules where as very few or no granules were seen in the rest of the ducts. 5. Alkaline phosphatase activity was most prominent but discontinuous in the luminal surface of the epithelium of efferential ductules and less marked in the connecting ductless. No enzyme activity was noted in the canal epithelium of epididyml duct. 6. India ink granules were most numerous in the epithlial cells of efferential ductules and were a few in connecting ductules. Very few or no granules of India ink were noted in the other types of the ducts. India ink granules in the epithelium increased gradually as the time after the administration of India ink (one up to twenty-nine hours) has proceeded. From those results it is suggested that epithelial cells of efferential and connecting ductules have active absorptive function, whereas the rest of duct system in the epididymis of the Rooster may be the mere pathway of the seminal fluid without significant modification of its constituents.

• 패션비즈니스
• /
• 제18권5호
• /
• pp.159-170
• /
• 2014

Recent concerns about the PFOA(perfluorooctanoic acid), have been increasing, which is generally applied in the water-repellent finishing process of textile products. It has been proven through animal testing to be harmful to humans, as possible carcinogens and neuro-toxic material. Thus U. S. Environmental Agency has gone as far as requiring the material to be eliminated in its entirety by 2015. As a viable alternative to this water-repellent finishing agent, the development of C6 product is gaining its popularity. The effects of PFOA finishing on the silk fabrics were examined, and we reviewed parameters of the needed process for optimizing appearance and functionality of silk fabrics treated with eco-friendly water-repellent finishing agent. Cross-linking agent affected the most on black color of reactive ink, among the physical properties. The contact angle reading was the highest in $8g/{\ell}$ of concentration for all fabrics. All the fabric specimens, subjected to the DTP and water repellent finishing, exhibited higher stiffness, where rayon specimen showed the highest, compared to the untreated specimens. The results may provide basic information leading to the development of value-added silk fabrics with water-repellency without excessive deterioration of the delicate appearance and inherent soft touch.

• Korean Journal of Chemical Engineering
• /
• 제35권12호
• /
• pp.2394-2402
• /
• 2018

Textile dyes are some of the pollutants which have received the most attention because of the large volume of wastewater generated by the textile industry. Removal by means of adsorption is one of the most versatile alternatives to treat these effluents. Even though different adsorbents such as activated carbons and mineral materials have been proposed, polymeric adsorbents are a viable alternative. This work reports for the first time the use of polyelectrolyte PTZ and macroelectrolyte MTZ containing tetrazole groups as adsorbents useful in the textile dyes removal present in aqueous solutions and wastewater. Because of the anionic character of the tetrazole group, MTZ exhibits selective adsorption capabilities for cationic dyes of up to $156.25mg{\cdot}g^{-1}$. The kinetic study of the process of adsorption shows that PTZ and MTZ fit a pseudo second-order model. MTZ also shows utility as a flocculant agent in the treatment of wastewater containing dyes Indigo Blue and Reactive Black. The results showed that PTZ and MTZ may be used in the treatment of wastewater in a process of coagulation-flocculation followed by the treatment by adsorption. This two-stage treatment removed up to 95% of the dye present in the wastewater. As well as removing the dyes, the values for COD, suspended solids, pH, and color of the wastewater decreased, thus significantly improving its quality.

• 한국식품저장유통학회지
• /
• 제18권3호
• /
• pp.328-334
• /
• 2011

폴리페놀화합물인 안토시아닌, 레스베라트롤, 쿼세틴, 카테킨, 에피카테킨류는 항암작용과 항산화작용을 하는 것으로 보고되고 있다. 본 연구에서는 다양한 국내 육성 포도 품종과 외국 도입 품종에 대하여 포도내 대표적인 폴리페놀계 화합물인 안토시아닌, 레스베라트롤, 쿼세틴, 카테킨, 에피카테킨류의 함량을 분석하였다. 전체적으로 카테킨 및 에피카테킨의 함량은 레스베라트롤과 쿼세틴보다 훨씬 높게 검출되었다. 폴리페놀계의 화합물은 과피색 간에 큰 차이는 보이지 않았으나, 동일 과피색내의 품종간에는 유의적인 차이를 나타냈다. 각 과피색 그룹에서 흑색 포도에서는 캠벨얼리, 청색 그룹에서는 세네카, 그리고 적색그룹에서는 베니가드 품종이 가장 높은 수치를 보였다. 성분별로 적게 함유하거나 전혀 검출되지 않는 품종도 일부 존재하였다. 이러한 결과는 향후 포도 육종개발 및 가공 분야에 응용되는 유용한 정보가 될 것으로 기대된다.

• 한국축산식품학회지
• /
• 제39권4호
• /
• pp.610-622
• /
• 2019

The aim of this study was to investigate the natural antioxidant activity of raw garlic (RG), aged black garlic (AG), and garlic fermented with Bacillus subtilis (FG) extracts on pork patty lipid oxidation throughout refrigerated storage. The total polyphenol, total flavonoid content, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activity of three different types of garlic extracts were measured. The total phenolic and flavonoid content of AG was significantly higher than that of FG and RG; FG also showed a significantly higher total phenolic content than that of RG (p<0.05). The DPPH and ABTS radical scavenging activity of AG and FG was significantly higher than that of RG and that of AG was significantly higher than that of FG (p<0.05). To investigate the effect of processed garlic extracts on pork patty lipid oxidation, freeze-dried extracts of RG, FG, and AG were added to the patties at levels of 0.5% (w/w). Patties containing 0.01% (w/w) ascorbic acid (AA) and patties without treatment (CON) were compared with patties containing garlic extracts. The pH value, 2-thiobarbituric acid reactive substances value, and volatile basic nitrogen value of pork patties containing AG and FG extracts were significantly decreased compared to the other groups (CON, AA, and RG; p<0.05). Taken together, these results suggest that AG and FG extracts possess strong antioxidative activity and can serve as natural antioxidative additives to prevent pork patty lipid oxidation.

• Safety and Health at Work
• /
• 제12권1호
• /
• pp.114-118
• /
• 2021

Background: Exposure to particulate matter (PM) emitted from vehicle exhaust might disrupt systemic function and elevate the risk of cardiovascular disease. In this study, we examined the changes of cardiometabolic biomarkers among vehicle inspectors exposed daily to PM0.25 and components. Methods: This cross-sectional study was conducted at two vehicle inspection centers, Pulogadung and Ujung Menteng, located in East Jakarta, Indonesia. The exposed respondents were 43 workers from vehicle inspection centers, and the unexposed group consisted of 22 staff officers working in the same locations. Vehicle exhaust particulate matter was measured for eight hours using a Leland Legacy personal pump attached to a Sioutas Cascade Impactor. The used filters were 25 and 37-mm quartz filters. The particulate matter concentration was analyzed using a gravimetric method, whereas trace elements were analyzed using energy dispersive X-ray fluorescence. An EEL Smoke Stain Reflectometer analyzed black carbon. Results: The personal exposure concentrations of PM0.25 were 10.4-fold higher than those in unexposed groups. Calcium and sulfur were the major components in the obtained dust, and their levels were 3.3- and 7.2-fold higher, respectively, in the exposed group. Based on an independent-samples t-test, high-density lipoprotein, triglyceride, HbA1c, total immunoglobulin E, high-sensitivity C-reactive protein, tumor necrosis factor-alpha, and nitric oxide levels were significantly different between the groups. Conclusions: In summary, it was suggested that PM0.25 exposure from vehicle exhaust might affect cardiometabolic biomarkers change.

• Korean Journal of Chemical Engineering
• /
• 제35권11호
• /
• pp.2283-2289
• /
• 2018

$TiO_2$ microspheres were successfully synthesised by simple solution phase method by using various amount of titanium butoxide as precursor. The prepared $TiO_2$ were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance absorption spectra (UV-DRS), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). XRD analysis revealed that the as-synthesized $TiO_2$ microsphere poses an anatase phase. The photocatalytic degradation experiments were carried out with three different dyes, such as methylene blue, brilliant black, reactive red-120 for four hours under UV light irradiation. The results show that $TiO_2$ morphology had great influence on photocatalytic degradation of organic dyes. The experimental results of dye mineralization indicated the concentration was reduced by a high portion of up to 99% within 4 hours. On the basis of various characterization of the photocatalysts, the reactions involved to explain the photocatalytic activity enhancement due to the concentration of titanium butoxide and morphology include a better separation of photogenerated charge carriers and improved oxygen reduction inducing a higher extent of degradation of aromatics.

• 한국축산식품학회지
• /
• 제41권5호
• /
• pp.826-839
• /
• 2021

A 60-d feeding trial was conducted to evaluate the effects of diets supplemented with two concentrations (0% and 0.3%) of black raspberry (Rubus coreanus Miquel) fruit by-product (RCFB) on the physicochemical characteristics, oxidative stability, antioxidant capacity, antioxidant enzyme activity, and fatty acid profile of M. longissimus dorsi (LL) porcine muscle from Berkshire finishing pigs meat. Results revealed that regardless of the sex, diets supplemented with 0.3% RCFB reduced (p<0.05) the thiobarbituric acid reactive substances (TBARS) expressed as malonaldehyde (MDA) content effectively. A higher antioxidant capacity [2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity] was found (p<0.05) in response to feeding supplemented with 0.3% RCBF for male or female pigs. Moreover, 0.3% RCFB dietary feed increased (p<0.05) the glutathione peroxidase enzyme activities (GPX1) in blood plasma for male or female pigs. However, no influences were observed (p>0.05) on meat color, WHC, shear force, and fatty acid contents while fed diet supplemented with 0% or 0.3% RCFB for male or female pigs. Overall, this study suggests that a diet supplemented with 0.3% RCFB may beneficially affect owing to better oxidative stability, higher antioxidant capacity, and antioxidant enzyme activity (blood plasma) in pigs which could be a promising natural antioxidant without affecting meat quality traits.

• 한국컴퓨터정보학회논문지
• /
• 제28권12호
• /
• pp.221-229
• /
• 2023

최근 전력 계통에 인공 관성, 감쇠, 블랙스타트 기능, 독립 운전 기능 등을 제공할 수 있어 많은 주목을 받고 있는 Grid-forming(GFM) 컨버터는 저전압 Microgrids(MG)에서 낮은 라인 임피던스의 X/R 비율과 작지 않은 전력각으로 인한 유효전력과 무효전력 간의 커플링 현상이 발생한다. 이러한 전력 커플링 현상은 GFM 컨버터의 안정성 및 성능 저하 문제, 부정확한 전력 공유 문제, 제어 파라미터 설계 문제를 유발하고 있다. 따라서 본 논문은 GFM 컨버터와 관련된 제어 방법뿐만 아니라 전력 디커플링 방법에 대한 검토 연구로서, 유망 제어 방법을 소개하고 전력 디커플링 방법에 대한 비판적 검토를 통하여 향후 연구 활동의 접근성을 높이고자 하였다. 이에 따라 전력디커플링 방법 연구를 위해 향후 연구자들이 쉽게 접근할 수 있어 분산 발전원 확대에 기여할 수 있을 것이다.