• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.168-169
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• 2013

• 한국조리학회지
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• 제23권6호
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• pp.20-26
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• 2017

To guarantee the safety of rice cake production, the Hazard Analysis Critical Control Points system was applied to the production process. The purpose of this study was to analyze the microbiological hazards of the manufacture of rice cakes, and establish critical limits in the process of the manufacturing rice cakes. To control the microbiological hazards, the sterilization process was set to a critical limit. The process of manufacturing rice cakes can reduce these microbiological hazards during the steaming process. A microorganism test for each specimen was conducted three times and compared with before and after steaming processes. The finished product was conducted by microbiology experiment and the validity of the steaming process was verified. The results were determined to be capable of reducing the biological element of Critical Control Point via the steaming process. Microbiology such as aerobic plate count, coliform, Escherichia coli(E. coli), Listeria monocytogenes, Enterohemorrhagic E. coli, Salmonella spp., Bacillus cereus, Staphylococcus aureus and Clostridium perfringens was evaluated by the experimental method of Korean Food Standards Codex. Aerobic plate count was reduced by steaming process, and no microorganism were detected. All rice cakes in the finished product were judged to be safe for both the Escherichia coli and general bacteria. In conclusion, it suggested that a HACCP plan was necessary for management standard and systematic approach in the establishment of critical limit, problem resolution, verification method, education, and records management. Based on this study, it is intended to provide a baseline for improving quality control standards and improving hygiene levels for small manufacturers.

• 한국방재학회 논문집
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• 제5권3호
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• pp.29-39
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• 2005

본 연구는 도시유역인 성내와 반포배수구역과 동의대시험유역에서 수문학적 특성에 따른 임계지속기간의 변화를 구명한 것이다. 유출해석을 위한 도시유출모형으로는 RRL, ILLUDAS, SWMM과 SMADA 모형을 사용하였으며, 수문학적 특성으로는 강우의 시간분포방법, 확률강우강도식, 선행함수조건, 재현기간과 유출모형을 이용하였다. 도시유역에서 최대 첨두유량을 발생시키는 강우의 시간분포방법은 Huff의 4분위로 나타났으며, 첨두유량은 수문학적 특성에 따라 차이를 보였으나 유출모형을 제외한 수문학적 특성들은 임계지속기간에 영향을 미치지 않는 것으로 나타났다. 임계지속기간은 유출모형에 따라 차이를 나타내고 있으며, SWMM 모형에 Huff의 4분위를 적용하였을 경우 임계지속기간이 가장 크게 나타났다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권6호
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• pp.271-277
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• 2003

It is important to control layer current distributions of coaxial multi-layer HTS cables, because a homogeneous layer current distribution decreases AC loss and can supply the largest operational current. We have extended the theory that treat the operational current more than the critical current by considering V-I nonlinear characteristics of HTS tapes including flux flow resistance and contacting resistance between the cable and terminals. It is important to investigate the current distribution under the condition of operational current more than the critical current of cable, because the cable has experiences of fault current. In order to verify the extended theory, we have fabricated a two layers cable with the same twisting layer pitch. It was observed that almost all the operational current less than the critical current flowed on the outer layer because of its lower inductance. In case of operational current more than critical currents of layers, the flux flow resistances affect strongly current waveform and thereby the currents of layers were determined by the flux flow resistances. And we investigated breakdown characteristics in $LN_{2}$/paper composite insulation system for the application to a HTS cable. In this experiment, we got some information out of that the electrical characteristics of the insulation materials depends on the condition of butt gap.

• 한국분무공학회지
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• 제1권4호
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• pp.46-53
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• 1996

The present study is aiming at improving the performance of main nozzle of an air jet loom with a modified reed and auxiliary nozzles. The double coaxial pipe jets consisting of a central air jet and an annular air jet have been experimentally investigated. The duter jet has a potential core and a constant velocity. The inner jet through an inner long pipe is induced by the subatmospheric pressure near the inner nozzle edge, and the jet velocity of an inner pipe is always lower than that of a outer pipe. The static pressures of the main nozzle over a wide range of the nozzle tank pressure were measured, and the nozzle velocity and Mach numbers were analytically calculated. Experiment81 results indicate that the critical condition of Mach number of unity to occur at the two positions in a main nozzle; one of them is the needle tip and the other is the acceleration tube exit An increase in the tank pressure causes the critical throat condition to occur at the two positions above. The velocity of acceleration-tube exit is maximum at the critical length L* and flow patter in acceleration-tube over critical lengh remains unstable.

• 한국안전학회지
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• 제21권5호
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• pp.6-11
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• 2006

This study aims to measure a smoke density and velocity by using the PIV method in case a fire occurs in tunnels. By doing so, this will estimate a critical velocity, examine its appropriateness, and present the basic materials necessary for designing a smoke control equipment. For this study, a visualization test was conducted based on the 1/20 miniature of a real tunnel according to the Froude scaling. As a part of basic experiments, a correlation between smoke density and brightness was analyzed here, and a critical velocity was estimated on the condition that a fire breaks out in tunnels. As a result, this study finds that there is a correlation between smoke density and brightness within a range of 100% to 30% transmittance, from which a quantitative smoke density can be obtained. The study also suggests that a critical velocity calculated from the Kennedy formula shows about 10% difference from that estimated in the test.

• 한국연초학회지
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• 제6권2호
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• pp.155-168
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• 1984

Field test were conducted to select the best method for soil phosphorus test and to obtain the critical levels of each method for P fertilizer recommendations based on tobacco production. Truog method was recognized to be the mort suitable one for soil P test. N. Carolina, Bray No.1 and Olsen methods were followed in order. Bray No. 2 and Lancaster methods showed the least satisfaction. The critical levels of available P by lancaster, Bray No. 1, N. Carolina,01sen, and Truog methods were 55ppm, 32ppm, 21ppm, 19ppm, and 22ppm, respectively. Below the critical level a large yield response can be expected with 10kg $P_2O_5$/10a, above critical level little or no response is expected. In soils the more the initial available p, the more available P was carried over, while the more the total amount of silt and clay, the less the residual P was found. The increase in residual P by 10kg of $P_2O_5$ was greater than that of 5kg/10a. The chemical composition and the price of the cured leaf were not affected by the $P_2O_5$ application, indicating that the increase in the rate of $P_2O_5$ application would not exert on the quality of tobacco.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.945-948
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• 2006

Chloride penetration into concrete is a hot issue of concern all over the world, notwithstanding, very few attempts have been conducted to explore the effect of cracks on choride penetration. Cracks provoke to lose a main function of watertightness of concrete and lead to reduce the service life of concrete. For this reason, it is necessary to define a critical crack width to prevent a quick chloride penetration through crack. In this study, experiment is focused on establishing a critical crack width in terms of chloride penetration. Concrete specimens with different crack widths I crack lengths have been subjected to rapid chloride migration testing. In a side of analytical solution, a simple approach to quantify the chloride diffusion coefficient of only crack zone excluding sound concrete was proposed. The result clearly showed a critical crack width of 0.03 mm. Based on the experimental results, a phenomenological model was proposed to explain the meaning of critical crack width in practical engineering. In this model, cracked concrete zone was divided into three zones. These zones corresponded to a wide crack, a zone with micro-cracks and an uncracked zone.

• Structural Engineering and Mechanics
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• 제84권3호
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• pp.337-344
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• 2022

Due to corrosion defects on the surface of the oil pipe, the sealing performance of the annular blowout preventer (BOP) decreases, and the leakage of toxic and harmful gases such as H₂S and SO₂ will threaten the safety of operators on the well. Therefore, this paper establishes the FE model for evaluating the sealing performance of BOP-oil pipe corrosion defects, which is based on the rubber large deformation theory and rubber core sealing mechanism, and designs the experiment of BOP sealing performance to verify the accuracy of the FE model. The sealing performance of BOP sealing oil pipe with corrosion defects is studied. The research results show that the sealing performance of BOP is more sensitive to the axial size of corrosion defects. With the increase of oil pipe outer diameter, the critical size of defects increases continuously. The sensitivity of radial and depth dimensions is low, When for 88.9 mm outer diameter oil pipe, the axial critical size of corrosion defect is 20 mm, the radial critical size is 16 mm and the critical depth is 2 mm. Fit the formula between the outer diameter of oil pipe and the piston increment. According to the formula, the operator can calculate the piston stroke increment required by the BOP to complete the sealing when the oil pipe is corroded.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.585-588
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• 2008

염해환경 하에 있는 철근 콘크리트 구조물의 내구수명을 평가하기 위해서는 콘크리트 중 철근의 부식 임계 염화물량, 콘크리트의 염소이온 확산계수 및 표면 염소이온량과 같은 재료의 정량적인 물성 파악이 필수적이고, 이들이 콘크리트의 내구수명 평가시 주요변수로 이용되고 있다. 그러나, 이들은 콘크리트 배합비, 시멘트 종류 및 환경 조건 등과 같은 여러 요인에 의해 영향을 받는 것으로 알려져 있다. 따라서, 본 연구에서는 콘크리트 중 철근의 부식 임계 염화물량을 보다 실제적으로 평가하기 위하여 물-시멘트비 31%, 42%, 50% 및 70%에 대해서 각주형 콘크리트를 제작한 다음, 이들에 대해서 동해안에 위치한 영덕에서 약 3년 동안 폭로 실험을 수행하였다. 실험이 진행되는 동안, 철근의 부식 개시 시기를 추정하기 위하여 시험체에 대해서 자연전위 측정에 의한 부식 모니터링을 수행하였고, 철근부식이 감지되었을 때 시험체를 파괴한 후 콘크리트 중 염화물량을 평가함으로써 보다 합리적이고 신뢰적인 임계 염화물량을 제시하였다. 결국, 콘크리트 중 철근의 부식 임계 염화물량은 W/C비에 의존하며, 콘크리트 피복두께와는 거의 무관한 것으로 나타났다.