• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.317-321
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• 2008

Piping in the Nuclear Power plants (NPP) are mostly consisted of carbon steel pipe. The wall thinning defect is mainly occurred by the affect of the flow accelerated corrosion (FAC) of fluid which flows in carbon steel pipes. This type of defect becomes the cause of damage or destruction of piping. Therefore, it is very important to measure defect which is existed not only on the welding partbut also on the whole field of pipe. Over the years, Infrared thermography (IRT) has been used as a non destructive testing methods of the various kinds of materials. This technique has many merits and applied to the industrial field but has limitation to the materials. Therefore, this method was combined with lock-in technique. So IRT detection resolution has been progressively improved using lock-in technique. In this paper, the quantitative analysis results of the location and the size of wall thinning defect that is artificially processed inside the carbon steel pipe by using IRT are obtained.

• 한국작물학회지
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• 제59권2호
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• pp.188-193
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• 2014

Seed viability testing provides valuable information for assessing seed lot germinability. However, most testing methods require destruction of seed prior to test. Because the dissected seeds for viability test cannot be used further evaluation, the nondestructively X-ray photography technique that can be applied for the evaluation of seed quality has been developed. In order to know the validity and accuracy of X-ray photography technique in seed evaluation test that conducted to remove the abnormal seed from a seed lot, we have compared the results from tetrazolium viability test, germination test and X-ray contrast method in cotton. Metallic salts treatment increased the efficiency of X-ray photographic method by enhancing the penetration of X-ray in abnormal or damaged seeds rather than normal seeds that have strong and well-organized tissues in seed. Cotton seeds presoaked for 16 hr in distilled water followed by soaking into metallic salt solution (5% NaI in water) for 60 min were easily classified seeds into dead seed and viable seed based on the radiography images obtained by X-ray radiation. We concluded that soft X-ray photography was reliable to find out the various defective characters due to heat and mechanical damage of seeds.

• 유기물자원화
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• 제25권1호
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• pp.47-55
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• 2017

유기성폐기물의 수열처리 기술은 고온에서 운전하여 에너지 소비가 큰 열분해 탄화기술의 단점을 보완하기 위한 방법으로, 세포벽을 파괴하여 탈수성을 향상시켜 탈수공정에서 함수율을 약 40% 수준까지 낮출 수 있는 장점을 가지고 있어 유기성폐기물의 고형연료화 분야에서 전 세계적으로 많은 연구가 진행되고 있다. 이에 본 연구에서는 수열처리가 유기성폐기물의 건조효율에 미치는 영향에 대하여 평가하였다. 대상물질로는 대표적인 유기성폐기물인 하수슬러지와 음식물류폐기물을 이용하여 $200^{\circ}C$에서 1시간동안 수열처리한 후 건조효율 변화를 관찰하였다. 유기성폐기물은 수열처리 후에 건조시간이 단축되어 $100^{\circ}C$에서 건조한 음식물류폐기물의 경우 원시료보다 건조시간이 52.9% 감소하였다. 따라서 수열탄화 반응이 하수슬러지와 음식물류폐기물의 건조효율을 상승시킬 수 있음을 확인하였다. 또한, 건조특성곡선의 예열기간에서 건조속도가 원시료 대비하여 각각 148%($80^{\circ}C$ 하수슬러지), 151%($100^{\circ}C$ 하수슬러지), 209%($80^{\circ}C$ 음식물류폐기물), 366%($100^{\circ}C$ 음식물류폐기물)로 모든조건에서 증가되는 것으로 보아 수열반응에서 세포벽이 파괴되면서 표면적이 늘어났음을 간접적으로 파악할 수 있었다. 건조시간이 단축됨에 따라 한계함수율이 높아져 감율건조기간이 증가하였으므로 이에 주의하여야 하며, 탄화정도에 따라 건조효율이 더 개선될 수 있을 것으로 기대된다.

• 대한안전경영과학회지
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• 제16권2호
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• pp.43-52
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• 2014

In weapon systems development, live fire tests have been frequently adopted to evaluate the performance of the systems under development. Therefore, it is necessary to ensure safety in the test ranges where the live fire tests can cause serious hazards. During the tests, a special care must be taken to protect the test and evaluation (T&E) personnel and also test assets from potential danger and hazards. Thus, the development and management of the range safety process is quite important in the tests of guided missiles and artillery considering the explosive power of the destruction. Note also that with a newly evolving era of weapon systems such as laser, EMP and non-lethal weapons, the test procedure for such systems is very complex. Therefore, keeping the safety level in the test ranges is getting more difficult due to the increased unpredictability for unknown hazards. The objective of this paper is to study on how to enhance the safety in the test ranges. To do so, an approach is proposed based on model-based systems engineering (MBSE). Specifically, a functional architecture is derived utilizing the MBSE method for the design of the range safety process under the condition that the derived architecture must satisfy both the complex test situation and the safety requirements. The architecture developed in the paper has also been investigated by simulation using a computer-aided systems engineering tool. The systematic application of this study in weapon live tests is expected to reduce unexpected hazards and test design time. Our approach is intended to be a trial to get closer to the recent theme in T&E community, "Testing at the speed of stakeholder's need and rapid requirement for rapid acquisition."

• Smart Structures and Systems
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• 제31권1호
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• pp.1-11
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• 2023

Assessment of the compressive strength of concrete plays a major role during formwork removal and in the prestressing process. In concrete, temperature changes occur due to hydration which is an influencing factor that decides the compressive strength of concrete. Many methods are available to find the compressive strength of concrete, but the maturity method has the advantage of prognosticating strength without destruction. The temperature-time factor is found using a LM35 temperature sensor through the IoT technique. An experimental investigation was carried out with 56 concrete cubes, where 35 cubes were for obtaining the compressive strength of concrete using a universal testing machine while 21 concrete cubes monitored concrete's temperature by embedding a temperature sensor in each grade of M25, M30, M35, and M40 concrete. The mathematical prediction model equation was developed based on the temperature-time factor during the early age compressive strength on the 1^st, 2^nd, 3^rd and 7^th days in the M25, M30, M35, and M40 grades of concrete with their temperature. The 14^th, 21^st and 28^th day's compressive strength was predicted with the mathematical predicted equation and compared with conventional results which fall within a 2% difference. The compressive strength of concrete at any desired age (day) before reaching 28 days results in the discovery of the prediction coefficient. Comparative analysis of the results found by the predicted mathematical model show that, it was very close to the results of the conventional method.