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Reliability Analysis on Safety Instrumented System by Using Safety Integrity Level for Fire.Explosion Prevention in the Ethyl Benzene Processes (Ethyl Benzene 공정에서 화재.폭발방지를 위하여 안전건전성수준을 이용한 안전장치시스템의 신뢰도 분석)

  • Ko, Jae-Sun;Kim, Hyo;Lee, Su-Kyoung
    • Fire Science and Engineering
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    • v.20 no.3 s.63
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    • pp.1-8
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    • 2006
  • The purpose of this work is to analyze quantitatively if the safety instrumented system(SIS) like the pressure safety valves(PSV) in the processes of ethyl benzene plant have been designed relevantly to the safety integrity level because overpressure in the benzene or ethyl benzene columns causes the explosive reactions, fires and reactor explosions. The safety integrity level(SIL) 3 has been adopted as a target level of SIS based on the general data of the Probability of Failure on Demand of PSV, $1.00E-4{\sim}1.00E-3$. The standard model of the reliability has been set up and then the fault tree analysis of it has been carried out to get the PFD of SIS, and the results show 8.97E-04, 5.37E-04, 5.37E-04 for benzene prefractionator column, benzene column and EB column, respectively. Thus, we conclude that the SIS is designed to fulfill the condition of SIL3, and when the partial stroke test for the control valve are carried out every sixth month, the SIS of each column is expected to increase its reliability up to $22{\sim}27%$.

A Case Study on the Change of Sampling inspection method for the Small Depth Charge Fuze (소형폭뢰용 수압식 신관의 품질검사방법 전환사례 연구)

  • Jee, Jae-Yong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.531-538
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    • 2017
  • In the case of hydraulic pressure type fuse, we accept or reject certain product lots by considering the number of defective products in the operating pressure test. Generally, this procedure, known as 'The inspection by attributes', has been most commonly used in the field of quality assurance of products. However, the method of inspection by attributes suffers because it tests more samples than inspection by variables. Even though the quality of the products has remained stable in the process condition, the same number of samples is required for every lot, which wastes time and money. This paper suggests that the lot acceptance procedure is changed from inspection by attributes to inspection by variables. We can calculate the statistical tolerance percent of defectives and compare this to the Acceptable Quality Level (AQL) in order to save money and time. It is also easier to monitor and control the quality of products by using the process capability index and x-bar charts. In conclusion, the procedure delivers mutual benefit to both the customer and the producer by securing high quality products and reference data.

Quality characteristics of Hijikia fusiforme extracts with different extraction method (추출방법에 따른 톳 추출물의 품질특성)

  • Kwon, Yu-Ri;Youn, Kwang-Sup
    • Food Science and Preservation
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    • v.22 no.1
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    • pp.70-77
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    • 2015
  • The physiological properties of water extracts from Hizikia fusiformis extracted using different extraction methods (water extraction, WE; autoclave extraction, AE; high pressure extraction, HPE) were investigated. The freeze-dried powder yields from HPE, AE and WE were 29.33, 27.84 and 23.63%, respectively. The $L^*$ and $b^*$ color values were higher in WE, while the $a^*$ color values were higher in WE and AE. The total sugar content of AE (60.14%) was higher than those of WE (47.10%), HPE (40.97%). The reducing sugar content (7.88%) and protein content (42.83%) of AE was higher than those of WE, and HPE. The uronic acid (5.04%), total free amino acid (785.19 mg/g), taurine (19.16 mg/g), aspartic acid (66.63 mg/g), asparagine (204.84 mg/g), alanine (188.87 mg/g) and ammonium chloride (243.91 mg/g) contents, however, were the highest in HPE. Additionally, the crude polysaccharide yield was higher in HPE (4.75%) than in AE and WE, and the crude saccharide (fucose, galactose, glucose, xylose and fucose) yields were higher in AE. It can be concluded that optimum conditions for the efficient extraction of Hizikia fusiformis depending on components are high pressure and a lower temperature than in the typical process.

Chemical Conversion Pattern of Salvianolic Acid B in Aqueous Solution under Different Decoction Conditions (달임 조건에 따른 Salvianolic Acid B의 구조변환 차이)

  • Lee, Hyoung Jae;Cho, Jeong-Yong;Lee, Sang-Hyun;Jeon, Tae-Il;Park, Keun-Hyung;Moon, Jae-Hak
    • Korean Journal of Food Science and Technology
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    • v.44 no.6
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    • pp.692-698
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    • 2012
  • The chemical conversion pattern of salvianolic acid B (Sal B) in aqueous solution under different boiling conditions was compared. When the duration of boiling was varied, without varying temperature or pressure, the content of chemically converted compounds (CCCs) was mostly increased over time. In addition, under different conditions of temperature and pressure with the same boiling time, the content of a few compounds increased with increasing temperature and pressure. These results confirmed that high temperatures and pressures in boiling alter the final composition of CCCs of Sal B. Therefore, it was suggested that the boiling conditions (time, temperature, and pressure) may be responsible for alteration of biological activities of the compounds. Our investigation of the chemical conversion of compounds contained in foods and medicinal herbs may provide important information in clarifying the biological activity of Sal B containing foods and medicinal herbs.

A Stdudy on SUS MASK Etching using of FeCl3 (FeCl3를 이용한 SUS MASK 에칭에 관한 연구)

  • Lee, Woo-Sik
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.13 no.5
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    • pp.412-418
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    • 2020
  • This paper produced an automatic fluid management system that can accurately control the specific gravity of etching solution(FeCl3), and produced a SUS MASK applied to OLED. The target was set at 0.4 mm in diameter of the hole. As a result of this misconception, the etching speed increased when the specific gravity(S.G) value of FeCl3 was changed from 1.43 to 1.49. And when the weight was 1.49, it was found that the vertical diameter was 0.405 mm, approaching the target. When pressure injection was varied from 2.0kg/cm2 to 3.5kg/cm2, the hole diameter at 3.0 kg/cm2 averaged 0.4mm, matching the target. The characteristics of the change in gravity were analyzed by applying the additive 1.2% and setting the weight at 1.430 by mixing HCl and H2O in FeCl3 and fixing the injection pressure at 3.0 kg/cm2. When the weight changed from 1.460 to 1.469 the etching speed increased from 0.564 to 0.540. When the weight was 1.467, the hole diameter was measured at 0.4 mm and the target was reached.

Process Simulation of HCNG Refueling System (HCNG 충전 시스템 공정모사)

  • Kim, Sang-Min;Han, Jeong-Ok;Lee, Yeong-Cheol;Lee, Joong-Seong;Kim, Yong-Cheol;Chae, Jeong-Min;Hong, Seong-Ho
    • Journal of the Korean Institute of Gas
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    • v.17 no.5
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    • pp.1-7
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    • 2013
  • In this study, simulation work of HCNG refueling system was performed. The hydrogen was produced from steam reforming process by natural gas. The conversion of natural gas is increased as SCR is increased. but it was no significant difference more than 3 of SCR and fuel throughput is increased as GHSV is increased. Both conversion and fuel throughput levels was optimized when the $1700h^{-1}$ of GHSV. CNG was compressed from low pressure natural gas. For the mixing of $H_2$ and CNG is mixed with the high pressure conditions such as 400bar of $H_2$ and 250bar of natural gas. Single-stage compression was required more power than multi stage. So, multi stage compression was suggested for high pressure compression. We calculated the intermediate pressure to minimize total required power of compressors. The intermediate pressure for $H_2$ and natural gas were derived at 61 and 65 bar, respectively.

Development of High Efficiency Dehumidifiers in low temperature (저온에서 고효율 제습기 개발)

  • Kim, Jong-Ryeol
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.9
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    • pp.206-211
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    • 2016
  • Various applications require dry air at low temperature, such automation equipment, semiconductor manufacturing, chemical production lines, and coating processes for the shipbuilding industry. Four evaporators for low temperature (below $0^{\circ}C$) were installed for a dehumidification system. Moist air is cooled sequentially over three evaporators. The first evaporator has an evaporation temperature of $13^{\circ}C$, that of the second evaporator is $5^{\circ}C$, and that of the third evaporator is maintained at $-1.3^{\circ}C$. In the fourth evaporator implantation thereby the moisture contained in the moisture air. A pressure regulator (CPCE 12) is used at this point and is defrosted when the vapor pressure is below a set value. The non-implantation moisture of the air is a heating system that uses the waste heat of a condenser with high temperature. It develops the cooling type's dehumidifier, which is important equipment that prevents the destruction of protein and measures the temperature and humidity at each interval by changing the front air velocity from 1.0 m/s to 4.0 m/s. The cooling capacity was also calculated. The greatest cooling capacity was 1.77 kcal/h for a front air velocity of 2.0 m/s

Slit Ventricle Syndrome in Children : Clinical Presentation and Treatment (소아에서 틈새뇌실 증후군 : 임상 양상 및 치료)

  • Shin, Beom-Sik;Yang, Kook-Hee;Kim, Dong-Seok;Choi, Joong-Uhn
    • Journal of Korean Neurosurgical Society
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    • v.30 no.sup2
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    • pp.309-315
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    • 2001
  • The term slit ventricle syndrome(SVS) refers to an episodic occurrence of headache, vomiting, and possibly some degree of impaired consciousness in shunted hydrocephalic children in whom slit-like ventricles are seen on CT scan or MRI. Authors present 6 cases with SVS who were treated at our institute for last 10 years. From 1986 to 1996, 821 patients underwent shunt surgery for hydrocephalus. The etiology of hydrocephalus included brain tumor(140 patients), post-hemorrhagic(62 patients), idiopathic normotensive hydrocephalus(64 patients), post-meningitic( 58 patients), post-traumatic(54 patients), congenital(48 patients), neurocysticercosis(31 patients), and unknown etiology(364 patients). During the mean follow-up duration of 68 months, 232 shunt revisions were performed by a revision rate of 1.28 per patient. The incidence of SVS was 0.7%(6 patients). Most of them have been operated on in infancy. Time interval from the first operation to the development of slit-ventricle syndrome ranged from 4 to 8 years, the mean was 6 years. Shuntogram showed patent shunt in all patients. Two patients with less severe clinical symptoms improved with conservative treatment. These patients were not measured ICP because of good hospital course. One patient showed high ICP and needed only revision with same pressure valve as previous shunt. Low ICP was noted in 3 patients. Pressure augmentation using an anti-siphon device(ASD) or upgrading valve system were necessary in these patients. The authors stress that determining type of SVS is the first step in treatment planning and that the best treatment is a strategy aimed at resolving the specific type of SVS responsible for the symptoms.

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Effect of Measuring Parameters of Tensile Strength of Fiber-reinforced Composite Materials (섬유강화 복합재료의 인장강도 측정변수에 따른 영향)

  • Lee, Jae-Dong;Jin, Young-Ho;Kim, Min-Seok;Son, Hyun-Sik;Kwon, Dong-Jun
    • Journal of Adhesion and Interface
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    • v.22 no.3
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    • pp.85-90
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    • 2021
  • Generally, the tensile strength of carbon fiber reinforced composite (CFRP) should be determined to produce this material. The tensile strength was performed based on ASTM D3039, and this test could cause the error by specimens and human. In this research, the CFRP tensile test was performed with different thickness of specimens and tap, adhesive for attaching tap, and pressure of jig to hold the specimens, while the test was performed based on ASTM D3039. The tensile stress and modulus exhibited differently with different specimen thicknesses, and the 1~1.5 mm thickness of the specimen was optimized. In the case of 0.28 MPa jig pressure, the slip or fracture at the clamping area of the specimen has not occurred, and specimens were fractured to the center section of the specimen. The adhesive to attach jig on specimen should be used to exhibit high adhesive stress. Experimental parameters could cause errors. It is expected to achieve an accurate tensile property evaluation of composite materials via improvements in adhesives, tabs, and jigs.

A Study on the Development of IoT Inspection System for Gas Leakage Inspection in Kitchen Gas Range Built-in Method (주방 가스레인지 빌트인 방식에서 가스 누출검사를 위한 IoT 검사 시스템 개발에 관한 연구)

  • Kang, Dae Guk;Choi, Young Gyu
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.15 no.4
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    • pp.283-290
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    • 2022
  • In this study, an IoT inspection system that can be linked with a server was developed using a gas timer and ESP-01 Wi-Fi module installed on a gas valve in the home. The server environment of the gas leak IoT inspection system was installed with APM (Apache, PHP, MySQL) to collect gas pressure data by generation so that leakage checks could be performed. In order to control the gas leak IoT inspection system, the app inventory was used to manage the gas leak check value in real time. In addition, user convenience has been enhanced so that membership management, WiFi settings, and leakage check values can be checked through mobile apps. In order to manage subscribers by region, the user list was checked by logging in in in the administrator mode so that the information on whether or not the leak test was conducted and the results could be provided. In addition, when the user presses the gas leak check button, the pressure is automatically checked, and the measured value is stored in the server, and when a gas leak occurs, the leakage check is performed after alarm and repair so that it can be used if normal. In addition, in order to prevent overlapping membership, membership management can be performed based on MAC addresses.