왕복동식 압축기에서 피스톤과 커넥팅로드는 중요한 부분이다. 이러한 주요부에 기계적 부하가 과도하게 가해지면 해당 기부 속이 손상될 수 있으며, 교체하기도 쉽지 않고 비용도 많이 든다. 따라서 내구성과 수명에 영향을 미치는 요인을 분석할 필요가 있다. 본 연구의 주요 목적은 피스톤과 커넥팅로드의 최대 응력 집중 위치를 확인하는 것이다. 이를 위해 설계된 공기압축기의 작업 공정의 동적 계산을 기반으로 피스톤 및 커넥팅로드의 응력 분석을 수행하였다. 공기압축기의 피스톤과 커넥팅로드의 3 차원 모델을 따로 설계하고, 이러한 부품들의 유한요소 해석은 수치해석적인 근사해법을 사용하였다. 피스톤은 열 경계 조건 없이 크랭크 샤프트의 각도에 따라 압 력 부하를 받는다. 시뮬레이션 결과는 피스톤과 커넥팅로드의 응력 집중 위치와 그 값을 예측하고 추정할 수 있다. 그 결과 크랭크 각도 135°와 225°에서 피스톤은 190MPa, 커넥팅로드는 123MPa 이상의 최대 등가응력이 나타났으며 이는 인장 항복강도 이하의 값이다. 또한, 커넥팅로드와 피스톤에 계산 된 안전 계수는 1보다 높게 나타났다. 더욱이, 이러한 결과는 왕복동 공기압축기 제작사에 피스톤 및 커넥 팅로드를 설계함에 있어서 최적화를 위한 참고 자료로 활용 될 수 있다.

본 연구는 전남 서남해안 우이도 주변해역의 조류흐름 특성에 따른 조류에너지 자원을 평가하였다. 먼저 대상해역의 조류특성에 관한 정보 수집을 통한 타당성 조사와 유한요소법을 적용한 수심평균 2차원 ADCIRC(Advanced Circulation) 수치모델로 조석과 조류속의 변화에 대한 모의실험을 수행하였다. 조석분조는 우리나라 해역에 가장 큰 영향을 미치는 4대 분조(M2, S2, K1, O1)를 기본으로 설정하였다. 실제 평균 수심이 반영된 수치모형의 4곳을 관측점으로 설정하여 분석한 결과, 대조기 때 고고조 2.2m, 최강조류속 1.33 m/s를 나타냈다. ADCIRC Model의 결과값은 국립해양조사원(KHOA) 실제 관측 자료와 비교 및 분석하여 검증하였다. 또한 대상해역의 수치모델 조류속값에 지형적 특성을 반영한 조류속기법(Tidal Flux Method)을 이용하여 조류에너지 밀도 분포에 대해 평가하였다. 우이도 해역의 5개 평가 영역 중 최대 1.75 kW/m²의 조류에너지 분포를 보였으며, 조위 및 조류속뿐만 아니라 해역의 지형적 특성을 고려한 조류에너지 밀도 분포도를 작성하여 최적의 조류발전단지 후보지를 선정하였다.

As manufacturing industries become globalized, product design affects every area of organization. The design sets the goals for a number of different departments, so if it fails to effectively communicate these goals, the entire organization is less efficient. In addition, To communicate clearly, the design must represent a product that meets its technical specification.GD&T (Geometric Dimensioning and Tolerancing) is one of the most important factors, which has an effect on efficiency of manufacture system, in designing products. However, most of designers in different industries are prone to ignore the importance of GD&T.To analyse the importance of GD&T compliance with international standards for design drawing, a comparison analysis of the difference between two methods, composite profile control and multiple single segment profile control, is performed on three different cases and suggests how it used to be more suitable.Composite profile tolerance is specified by a dual feature control frame that has one profile symbol specified with two lines of tolerance information. Whereas a multiple single segment profile control is when two or more single segment profile callouts are used to define the location and/or orientation and/or size and/or form of a part feature. In this study, the following results will be provided : a clear definition and an obvious difference of the tolerance zone, datums and datums sequence and minimization of tolerances.On this study, composite profile tolerance and multiple single segment profile tolerance were discussed. Next steps of research will consist on reaching more accurate results for profile control. Further research will be focused on dealing with the remaining 14 symbols of GD&T.

This study was performed in order to analyze the fibrinolytic, thrombin inhibitory, anti-oxidative, acetylcholinesteraseinhibitory, and immuno-enhancing activities of the water extract and solvent fractions isolated from Grifola frondosa. Fibrinolyticactivity was analyzed using the fibrin plate method, and thrombin inhibitory activity was assayed using the substrate H-D-Phe-pip-arg-pna. Anti-oxidative activity was estimated using the DPPH assay, and AChE inhibitory activity was measured using thespectrophotometric method. Immuno-enhancing activity was examined using the nitric oxide (NO) production in RAW 264.7macrophage cells. Cell viability was determined using the MTS assay. Fibrinolytic activities were the highest in water extract (1.55plasmin units/mL) followed by water fraction (0.85 plasmin units/mL). The thrombin inhibitory activities of the water and ethylacetate fractions were determined to be 76.43% and 72.59%, respectively. The acetylcholinesterase inhibitory activities ofchloroform and hexane fractions exhibited values of 95.14% and 94.74%, respectively. The butanol fraction showed the highestanti-oxidative activity at 94.47%. Anti-proliferating activity against Raw 264.7 cells showed no cytotoxicity. The production of NOin Raw 264.7 cells increased up to 2-fold by adding the water fraction compared to the untreated control. These results suggestthat Grifola frondosa may serve as a useful functional food for the enhancement of immune function and the prevention andtherapy of cardiovascular diseases.

Compressed air has many uses on board ship, ranging from diesel engine starting to the cleaning of machinery during maintenance. In an effort to enhance the performance of the marine compressed air system, this work studied a way to reduce condensation from the air compressor via experiments. Especially more condensation is produced when the temperature at compressor outlets and the humidity of the air are higher. so in the research, drain production change has been observed by additionally installing the cooling fan on the suction portion of the air to air compressor and this is the method for reducing the compressed air drain that has passed through the compressor. For the result, it was verified that when the cooling fan was used, less drain was made where per hour it was 500.9ml of drain and the measured result after installing the cooling fan was that less drain was made. Other additional and various researches are needed including experiments like silica gel passing through the suction portion afterwards.

By increasing the flow rate of near the river the water level increases. Due to the increased water level, damage occurs in the revetment. In this paper, In oder to estimate the amount of overtopping rate in the revetment near the river the numerical mode

A series of activated carbons were prepared from coconut shells and coal-tar pitch binder by physical activation with steam in this study. The effect of variable processes such as activation temperature, activation time and ratio of mixing was investigated for optimizing those preparation parameters. The activation processes were carried out continuously. The nitrogen adsorption isotherms at 77 K on pellet-shaped activated carbons show the same trend of Type I by IUPAC classification. The average pore sizes were about 19-21a. The specific surface areas (SBET) of pellet typed ACs increased with increasing the activation temperature and time. Specific surface area of AC treated for 90 min at temperature 900℃ was 1082 m2/g. The methylene blue numbers continuously increased with increasing the activation temperature and time. On the other hand, iodine numbers highly increased till activation time of 60 min, but the rate of increase of iodine numbers decreased after that time. This indicates that new micropores were created and the existing micropores turned into mesopores and macropores because of increased reactivity of carbon surface and H2O.

산수유 열수추출물의 혈전용해활성을 탐색하고, 유기용매로 분획화한 에틸아세테이트(ethyl acetate) 분획물에서 1.36 plasmin units/mL의 강한 혈전용해활성을 확인하였다. Amberlite IRA-400, Sephadex LH-20 column, active charcoal column 과 재결정으로 정제한 혈전용해화합물을 HPLC로 분석 비교한 결과, 표준물질인 malic acid와 같은 retention time (RT)을 나타내고, LC/MS/MS 분석의 Negative mode 측정 시 m/z 133에서 같은 peak를 나타내어 정제한 화합물이 분자량 134 Da인 malic acid 임을 확인하였다. 정제한 화합물은 0.69 plasmin units/mL의 혈전용해활성을 보이고, 14.62%의 트롬빈 저해활성을 나타냈으며, 6.42%의 항산화 효과와 17.28%의 항당뇨 효과를 나타냈다. 분리한 화합물은 섬유소원의 Aα chain, Bβ chain과 반응하지 않았지만 γ chain을 분해하는 것으로 나타났다. 위 연구 결과를 바탕으로 산수유에서 분리한 혈전용해화합 물은 혈관계 질환의 치료제 개발과 기능성 식품 개발을 위한 우수한 소재로 이용 가능할 것으로 예상된다.

Paeonia japonica is a perennial flowering plant used in traditional medicine therapy. The purpose of this study was to investigate the effect of water extract and solvent fractions obtained from P. japonica on anti-oxidative, anti-thrombin, anti-invasive and pro-apoptotic activities in YD-10B cells, human oral squamous carcinoma cell line. Water fraction revealed the highest extraction yield at 11.44% (w/w). Anti-oxidative activity was the highest in ethyl acetate fraction (85.13%). In the thrombin inhibitory activity test, ethyl fraction was the highest, with a value of 87.54%. Release and activation of MMP-2/pro-MMP-2 ratio in thrombin-treated YD-10B cells were significantly inhibited in the ethyl acetate fraction. At a concentration of 120 ㎍/㎖, water extract and solvent fractions of P. japonica inhibited cell proliferation in YD-10B cells except water fraction. Pro-apoptotic effect on human oral squamous carcinoma cell using the Bax/Bcl-2 ratio analysis was higher in water extract than other fractions. These findings suggest that the ethyl acetate fraction of P. japonica potentiates a promising antioxidant, anti-thrombin and anti-invasive agents.

The purpose of this study was to investigate the possibility of application of microwave energy for the fabrication of polymer/clay nanocomposite. APES/Clay nanocomposites were prepared at 130℃ for 30min with various content of clay by melt-intercalation method under classical and microwave heating source. APES/Clay samples were characterized by the means of X-ray diffractometry(XRD), thermal gravimetric analysis(TGA), and rheometric dynamic analysis(RDA). It was found that intercalated or exfoliated state was obtained in the samples according to the condition of organic modification, clay content, and heating source.