• 수산해양기술연구
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• 제28권2호
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• pp.171-183
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• 1992

In this paper, the behaviour of cavitation erosion, influence of corrosion and corrosion control on slide bearing metals for internal combustion engine were investigated, and this experiment was done by the vibratory cavitation erosion tester. The main results obtained are as follows: 1. With decreasing the space between horn and specimen, the weight loss and its rate increased step by step. But the weight loss and its rate of 0.2mm space decreased conversely more than that of 0.4mm space at early stage. 2. The weight loss and its rate with change of pH were appeared to the order of pH2>pH12>pH7>pH4. And the weight loss and its rate at pH 4 decreased at best. 3. The weight loss and its rate by cavitation erosion for bearing metals were shown to the order of W.M7>W.M1>K.M4. 4. There appeared mainly small pit hole at pH2, and appeared the pit of netting thread type at pH12 by the results of the damaged surfaces at pH2 and pH12 environments that were sensitive to cavitation erosion. 5. With increasing the viscosity of lubricating oil, the weight loss rate by cavitation erosion became dull at the space below 0.5mm. 6. The protective efficiency of cavitation erosion-corrosion is superior inhibitor of chormate(25 ppm) to cathodic protection.

• 유기물자원화
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• 제13권4호
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• pp.107-117
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• 2005

본 연구에서는 펜톤산화 공정을 축산폐수의 전처리 시스템으로 활용하고자 초기 pH, $H_2O_2/Fe^{2+}$ 비율, $H_2O_2/Fe^{2+}$ 약품주입량, 응집 및 침전을 위한 중화제 등과 같은 펜톤산화의 적정 운영조건을 도출하는 실험적 연구를 실시하였다. 적정 조건을 도출하기 위해 교반시험기를 이용하여 120 rpm에서 2시간 동안 각 조건을 변화시키면서 펜톤산화 반응을 진행한 후 2시간 동안 침전시켜 그 상등액의 잔류 과산화수소, $COD_{Cr}$, SS 등을 분석하였다. 실험결과 도출된 최적조건은 초기 pH는 4, $H_2O_2/Fe^{2+}$비율은 10:1, $H_2O_2/Fe^{2+}$ 약품주입량은 5,000/500mg/L 그리고 중화제로는 $Ca(OH)_2$가 양호한 것으로 나타났다. 이러한 최적 조건에서 펜톤산화에 의해 축산폐수의 $COD_{Cr}$ 제거율은 43% 그리고 SS는 84%의 제거율을 나타내었다.

• 한국생산제조학회지
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• 제7권3호
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• pp.99-103
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• 1998

The curved surface machined by plate end mill causes a excess non-cutting volume, in these cases ball end mill is used for the curved surfaces. This study is aimed to obtain the optimum cutting conditions of various cutting speed, table speed, tool diameter, radius of curvature roughness on the conditions of various cutting speed, tool diameter, radius of curvature when machining the curved surface using the ball end mill. After designing curve rates, obtaining NC data by CAD/CAM system through CC-Cartesian method and transferred the data through DNC system, we machined the specimens by the CNC machining center, The surface roughness of specimens was measured by surface roughness tester and CNC 3D coordinate measuring machine. The cutting condition were the same as follow velocity; 15, 20, 25 30m/min, feed rate;40, 60, 80, 100m/min and radius of curvature; 30,40,50,60mm, tool diameters; ø8, ø12, ø16, ø 20mm. Analizing the working results, we can acquire the optimum cutting condition of curved specimen at the cutting velocity of 20~25m/min and the feed rate of 80mm/min. As the same cutting condition the best surface roughness was showed at ø16mm of the tool diameter. But the tool diameter was smaller than ø8mm. we could improve for the surface roughness by controlling the cusp.

• 한국산업보건학회지
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• 제27권4호
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• pp.283-290
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• 2017

Objectives: This study aimed to evaluate the relationship between filter replacement and filter performance change in particulate filters used in the workplace. Methods: Three types of particulate respirator filters are mainly used in the workplaces. These were tested against the filter performance safety certification standard for dust masks established by the Ministry of Employment and Labor(MoEL). Used filters were collected to test their performance, such as filter pressure drop, efficiency, and quality factors. All these factors were evaluated by a filter tester. To compare filter performance between used and new ones, the same kinds of new filters were also tested together under the same procedures. Results: A total of 270 used filters were collected for testing. The main reasons to replace the filters were difficulty in breathing(46.2%), dirty/odor influx(19.7%), and a combination of factors(26.7%). The pressure drop for two special class groups was significantly different(new filters: $20.72{\pm}3.33mmH_2O$; used filters: $24.70{\pm}5.26mmH_2O$, p<0.0001). In the case of penetration, new filter groups indicated $0.0032{\pm}0.0040%$, while that of the used filters was $0.0596{\pm}0.1187%$. The quality factor for the used filters($0.34{\pm}0.09$) significantly decreased compared to the new filters($0.53{\pm}0.08$) (p<0.0001). Conclusions: Filter performance including pressure drop, penetration, and the quality factor was evaluated and compared between new and used filters in the workplace. The results showed that general filter performance deteriorated more for change of pressure drop, penetration and the quality factor.

• 한국식품과학회지
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• 제4권1호
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• pp.6-12
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• 1972

Fay Elberta freestone peaches were harvested at four maturity levels as judged by skin color and firmness. They were ripened at $68^{\circ}F$ under 80 percent relative humidity for 4, 6, 8 and 10 days respectively prior to canning. Results indicate that both harvest maturity and ripening conditions are important factors influencing quality, flavor and composition of canned freestone peaches. Peaches harvested at $18{\sim}24$ pounds on a Magness-Taylor pressure tester with a 7/16' plunger(M1) failed to ripen satisfactorily. Fruits harvested at $13{\sim}17$ pounds (M2) pressure test ripened successfully at $68^{\circ}F$ within 6 to 8 days; and those harvested at 6 to 12 pounds (M3) needed 4 days for ripening at $68^{\circ}F$. Tree-ripened fruits (M4) were undesirable for canning because of the high percentage of bruised fruits. The optimum firmness for canning appears to be in the range of 1.5 to 3.0 pounds. The titratable acidity of peaches decreased during maturation and ripening. The tannin content of peaches at M1 maturity decreased with ripening at $68^{\circ}F$. But no appreciable change was observed in the M2 and M3 series which were ripened at $68^{\circ}F$ for 4 to 10 days. The volatile reducing substances (V.R.S.) increased as the peaches developed on the tree and also during post-harvest ripening. The effect of harvest maturity and post-harvest ripening on color grade of the canned peaches is presented. Little difference was found in the flavor and composition of peaches peeled by the cup-down lye peeling and the steam-peeling methods. The cup-down lye-peeling method might be most advantageous because of its higher peeling efficiency.

• 대한안전경영과학회지
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• 제17권2호
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• pp.147-152
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• 2015

Through the inspector's real name to improve the quality of inspection is to show the design Radiological examination pursuant to the Ordinance of the Ministry of Health and Welfare for patient safety in the Image. However, the use of existing and in EMR, equipment within the handwriting input, the individual initial use has a problem. In this study, increasing the stability of the patient and the precise inspection, In order to increase the efficiency and convenience than the real-name system for quality control inspectors of medical equipment, Using the EMR and PACS developed and applied to evaluate the usefulness of automatic enrollment. Enter your information in the EMR, which was developed markers that inspectors use to compare the before and after images PACS satisfaction. Convenience than using traditional, consistency, the entry of the missing were higher as a statistically significant difference. A test strip automatic enrollment programs are developed in this study. You can increase the stability of the patient by checking the image to show the real tester, we expect the quality of care would be improved.

• 한국가스학회지
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• 제8권1호
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• pp.1-6
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• 2004

선박용 열교환기의 냉각수로 사용되고 있는 해수의 입구온도는 스팀터빈콘덴서의 경우 약 $25^{\circ}C$이고 출구온도는 약 $60^{\circ}C$이며, 오일쿨러의 경우 출구온도는 약 $40^{\circ}C$이다. 이러한 해수의 온도 변화는 열교환기 세관재의 부식특성에 크게 영향을 미친다. 그러므로 부식손상을 최소화하면서 열교환 효율을 최대로 유지할 수 있는 냉각용액의 온도설정은 매우 중요하다. 따라서 본 연구에서는 $3.5\%$ NaCl + $0.1\%\;NH_4OH$ 수용액의 유동하에서 선박용 열교환기 세관재로 사용되고 있는 Al-황동의 분극 및 응력부식균열 실험을 실시하여 분극특성, 응력부식균열거동 및 탈아연특성에 미치는 용액의 온도의 영향에 대하여 고찰하였다.

• Bulletin of the Korean Chemical Society
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• 제13권6호
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• pp.620-624
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• 1992

The analytical performance of glow discharge mass spectrometer (GD-MS), using a flat type ion source is discussed. The efficiency of ion extraction was maximized at the distance between anode and cathode of 6 mm. At the operation condition of 4 mA, -1000 volt, and 1 mbar for the source, the optimum voltages for sampler and skimmer were40 volt and -280 volt, respectively. The intensities of Cu, Zn, and Mn were increased as a function of square root of current approximately. Korea standard reference materials (KSRM) were tested for an application study. The detection limits of most elements were obtained in the range of several ppm at the optimized operating condition. The peaks of aluminum and chromium were interfered by those of residual gases. The depth profile of nickel coated copper specimens (3, 5, 10 ${\mu}m$ thickness) were obtained by plotting time versus intensities of Ni and Cr after checking the thickness of nickel coated using a scanning electron microscope (SEM). At this moment, the sputtering rate of 0.2 ${\mu}m/min$ at the optimum operating condition was determined from the slope of the plot of time to the coating thickness. The roughness spectra of specimen's crater after 16 min, discharge were obtained using a Talysuf5m-120 roughness tester as well.

• 한국인터넷방송통신학회논문지
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• 제22권3호
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• pp.139-143
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• 2022

본 연구에서는 전자기 유도 발전(EMG) 기법 중 RFPM의 설계사양을 설정하고 특성 계산에 필요한 유한요소해석(FEM, 2D)을 통하여 이에 적합한 시험 시제품을 제작하였다. 또한 시험용 프로토타입의 측정, 분석을 하기위하여 전용 검사장치를 설계, 제작하였다. 검사장치로 시험품을 측정하였으며, 그 결과를 분석하여 실제 인체 운동 에너지를 이용하여 웨어러블 IT 기기의 배터리에 충전이 가능한 만큼 출력전력이 생성되어 적용할 수 있는 방법을 제시하고자 한다. 시험결과, 회전수 780.9rpm, 토크 0.264kgf/cm, 부하전류 73.6~73.9mA의 조건에서 출력 1.679W, 효율 79.31%로 측정되었다. 따라서 초소형 RFPM 진자 발전기의 출력으로 웨어러블 기기에 충전이 가능한 것으로 분석되었다.

• 한국지반환경공학회 논문집
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• 제20권2호
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• pp.41-48
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• 2019

국내에 많은 도로공사, 공항공사, 항만공사, 구조물 되메우기 공사 등의 토목공사에서 흙의 다짐은 가장 중요한 공정 중 하나이다. 특히 도로공사에서 흙의 다짐공사는 노체다짐과 노상다짐으로 구분하며 다짐도 부족으로 부실공사의 원인으로 작용하기도 하는 중요한 작업이다. 현재는 여러 가지 다짐도 측정방법이 있으나 가장 많이 사용되는 평판재하시험이나 모래치환법에 의한 흙의 단위중량 시험방법을 가장 많이 사용하고 있으나 경제성이 없어 여러 측정방법이 개발되고 있다. 간편한 다짐도 측정 방법의 목적으로 측정기를 개발하고 제작한 것이 자유낙하 관입깊이별 다짐도 시험기(Free-Fall Penetration Test; FFPT)이다. 본 연구에서는 실내시험을 위하여 균질한 시료를 공사현장에서 확보하여 체가름 시험을 통해 흙을 분류하고 입도분석시험과 비중시험을 실시하였다. 자유낙하 관입깊이별 다짐도 시험기(FFPT)의 원리는 지구중력을 이용한 자유낙하 물체의 선단에 설치된 관입 침이 노체 또는 노상의 다짐이 완료된 노면에 관입 되는 깊이를 관측하고 그 위치에 모래치환법에 의한 흙의 단위중량시험을 통하여 다짐도 값을 구하여 분석하고 연관성을 검증하는 것으로 흙의 최대허용입경이 2.36mm로 시험하였으며 $A_1$다짐의 경우는 낙하고 10cm에서 시험한 결과 값으로 추세선을 작성하고 추세선의 결정계수 $R^2=0.8677$ 값을 도출하였으며 $D_2$다짐의 경우는 낙하고 20cm에서 측정 시 결정계수 $R^2=0.9815$ 값이 관측되었다. 자유낙하시험은 낙하높이를 10cm에서 50cm까지 10cm 간격으로 변경을 하면서 시험하였다. 본 연구는 모래치환법에 의한 흙의 단위중량시험을 통하여 얻은 다짐도 값과 FFPT 시험기를 통해 얻은 관입침의 관입깊이와의 연관성을 비교 분석하여 현재의 다짐도 측정방법의 단점인 시간, 장비, 인력의 소모를 최소화하여 경제성을 확보하고 정확성과 간편성을 보장하는 다짐도 측정기 제작으로 여러 공사현장에서 다짐도 측정이 간단하게 진행될 것이다.