• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.468-468
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• 2014

우리나라는 미국, EU, 러시아, 중국, 인도 등 다국간 협력 사업인 국제핵융합실험로(ITER) 사업에 참여하고 있으며, 블랑켓 일차벽 및 시험용 블랑켓 모듈(Test Blanket Module, TBM) 제작기술 개발에 필요한 고열부하 검증시험을 국내에서 자체적으로 실시하기 위한 고열부하시험 시설을 구축하였다. 한국원자력연구원에 설치된 고열부하시험 시설의 주요 사양은 다음과 같다. 열원으로는 전자빔을 사용하며, 빔출력은 최대 300 kW이고, 최대 출력밀도는 $10GW/m^2$이다. 전자빔의 최대 가속전압은 60 kV이고, 최대 조사 면적은 설계상 $70cm{\times}50cm$이다. 고열부하 장비는 핵융합환경과 유사한 고열부하를 시험대상물에 인가하여 접합 및 냉각 성능을 평가하는 장비이며, ITER 블랑켓 및 TBM 일차벽의 경우 약 $0.5MW/m^2$, 가속실험 혹은 사고 시 순간 시나리오 해석을 위해서 $5MW/m^2$까지 고려되기도 한다. ITER 블랑켓 일차벽 제작기술 개발 및 검증(2004~2011)에서는 외국장비(러시아 TSEFEY, 일본 JEBIS, 독일 JUDITH)를 활용하였으나, 고비용 문제와 장비 이용 시간의 제한에 따라 사용이 어려워, 국내에서는 KoHLT-1, 2 장비를 자체 구축하여 활용하여 왔다. 현재는 높은 열부하 인가조건, 약 $5MW/m^2$을 달성하기 위해서 전자빔을 이용한 고열부하시험 장치를 마련하였으며, ITER 블랑켓 일차벽 Semi-Prototype 검증시험, TBM, KSTAR 디버터 실험 등 핵융합로 일차벽 개발에 활용하고 있다. 전자빔, 전원 및 진공 chamber 등 전체 고열부하 시험장치를 구축하여 ITER 장치를 포함해서 토카막 디버터 등 핵융합 플라즈마 대면부품 (Plasma Facing Components, PFC) 재료 개발과 국방, 항공우주 분야의 열유속 게이지 측정법 향상 연구, 로켓 추진 엔진 연소실의 열유속 모니터링 연구, 항공기 프로펠러 연구 등에 활용할 수 있을 것으로 기대된다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.4
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• pp.376-382
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• 2018

We investigated the effect of replacing tuna byproduct meal (TBM) and rice bran (RB) with fish meal (FM) and macroalgae (MA) in extruded pellets (EP) supplied as a diet to juvenile Abalone Haliotis duscus in aquaculture. In total, 80,000 juvenile abalone were distributed among eight indoor raceways and supplied with one of four experimental diets. The control diet consisted of FM, fermented soybean meal, corn gluten meal and shrimp meal as protein sources, with wheat flour and dextrin as carbohydrate sources; the control diet also contained MA. In the FM50 diet, TBM was replaced with 50% FM. In the MA 50 diet, RB was replaced with 50% MA. The final diet, FM50+MA50, included TMB and RB in place of 50% FM and 50% MA. Abalone were fed to satiation with little food leftover for 16 weeks. Weight gain and specific growth rate of abalone fed the control diet were greater than those of abalone fed the FM50 and MA50 diets, but not different from those of abalone fed FM50+MA50 diet. The proximate composition of abalone soft body did not vary according to experimental diets. Based on these results, it appears that the traditional commercial diet for juvenile abalone, comprising FM and MA, could be replaced with one containing 50% TBM and 50% RB without any retardation of growth.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.171-177
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• 2005

Fire in underground space may induce severe structural damage as well as heavy casualties. To protect underground structure and passengers from fire, it is very essential to characterize fire-induced damage on construction materials of underground structures. In this study, the high-temperature furnace was manufactured to evaluate fire-induced damage on underground structure materials. Especially, this study aimed at the evaluation of fire-induced damage on the shield TBM concrete segment. In the fire tests, furnace temperature was set to reach 1,200 degrees at five minutes after Ignition. The temperature of 1,200 degrees was kept during one hour, and the fire was extinguished after two hours elapsed. From the temperature measurement by thermocouples embedded in test specimens, the spatting was estimated to reach approximately 20 cm from the surface exposed to fire. After the fire tests, the alteration of physico-mechanical properties and microstructures of concrete segment was investigated from core specimens. The results showed that apart from spatting, the deterioration depth of the remaining concrete material amounted to approximately 10 cm from the spatting surface.

• Journal of the Korean GEO-environmental Society
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• v.20 no.2
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• pp.29-40
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• 2019

Mechanized constructions have been frequently increased in soft ground below sea bed or river bed, for urban tunnel construction, and for underpinning the lower part of major structures in order to construct a safer tunnel considering various risk factors during the tunnel construction. However, it is difficult to estimate the subsidence behavior of the ground surface due to excavation and needs to be easily predicted. Thus, in this study, when a twin tunnel is constructed in the soft ground, it is proposed a simpler equation relating to the settlement behavior and a corrected formula applicable to soft ground and large diameter shield tunnels based on the previously proposed theory by Peck (1969). For this purpose, it was analyzed to long-term measurement values such as the amount of maximum settlement, the subsidence range by ground conditions, and interference volume loss due to the parallel construction, etc. As a result, a equation was suggested to predict the amount of maximum settlement in the soft sediment clay ground where is located at the upper part of the excavation site. It is turned out that the proposed equation is more suitable for measurement data in Korea than Peck (1969)'s.

• Tunnel and Underground Space
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• v.31 no.1
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• pp.25-40
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• 2021

As the era of Industry 4.0 arrives, the researches using artificial intelligence in the field of rock engineering as well have increased. For a better understanding and availability of AI, this paper analyzed the types of algorithms and how to apply them to the research papers where AI is applied among domestic and international studies related to tunnels, blasting and mines that are major objects in which rock engineering techniques are applied. The analysis results show that the main specific fields in which AI is applied are rock mass classification and prediction of TBM advance rate as well as geological condition ahead of TBM in a tunnel field, prediction of fragmentation and flyrock in a blasting field, and the evaluation of subsidence risk in abandoned mines. Of various AI algorithms, an artificial neural network is overwhelmingly applied among investigated fields. To enhance the credibility and accuracy of a study result, an accurate and thorough understanding on AI algorithms that a researcher wants to use is essential, and it is expected that to solve various problems in the rock engineering fields which have difficulty in approaching or analyzing at present, research ideas using not only machine learning but also deep learning such as CNN or RNN will increase.

• KNOM Review
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• v.24 no.1
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• pp.13-19
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• 2021

In recent, there is research to maximize production by preventing failures/accidents in advance through fault diagnosis/prediction and factory automation in the industrial field. Cloud technology for accumulating a large amount of data, big data technology for data processing, and Artificial Intelligence(AI) technology for easy data analysis are promising candidate technologies for accomplishing this. Also, recently, due to the development of fault diagnosis/prediction, the equipment maintenance method is also developing from Time Based Maintenance(TBM), being a method of regularly maintaining equipment, to the TBM of combining Condition Based Maintenance(CBM), being a method of maintenance according to the condition of the equipment. For CBM-based maintenance, it is necessary to define and analyze the condition of the facility. Therefore, we propose a machine learning-based system and data model for diagnosing the fault in this paper. And based on this, we will present a case of predicting the fault occurrence in advance.

• Journal of Life Science
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• v.27 no.11
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• pp.1269-1275
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• 2017

Tenebrio molitor samples were investigated as novel biomaterials and sources of food in several recent studies. However, the insects' effects on hair growth were not sufficiently researched. To develop novel and natural materials for preventing alopecia and promoting hair growth, this study investigated the antioxidant activities and hair-growth promotion effects of TMEs. To determine the antioxidant activities, the TMEs' DPPH radical- and nitrite-scavenging activities were examined. To determine hair-growth promotion effects, proliferations of human dermal papilla cells (DPCs) and the murine fibroblast cell line NIH3T3 were evaluated by using an MTS assay. In addition, estimations were made for cell viabilities against cell death induced by dihydrotesterone (DHT) in DPCs and inhibitory effects against potassium channel blocking induced by tolbutamide (TBM) in NIH3T3 cells. The DPPH radical scavenging activity was 81.17%, and the nitrite scavenging activity was 43.69%; the activities were similar to the activities of blueberry extracts. Moreover, the TMEs promoted the proliferation of human DPCs and NIH3T3 cells, which were concentrated dependently. The TMEs prevented not only DHT-induced DPC cytotoxicity but also TBM's action as a potassium channel blocker in NIH3T3 cells. The results suggested that TME could be used as a functional therapeutic alopecia reagent, to prevent hair loss and to promote hair growth.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1049-1060
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• 2018

Soil conditioning is one of the key factors for successfull tunnel excavations utilizing the earth pressure-balanced (EPB) shield tunnel boring machine (TBM) by increasing the tunnel face stability and extraction efficiency of excavated soils. In this study, conditioning agents are mixed with the weathered granite soils which are abundant in the Korean peninsula and the workability of the resulting mixture is evaluated through the slump tests to derive and propose the most suitable conditioning agent as well as the most appropriate agent mix ratios. However, since it is cumbersome to perform the slump tests all the time either in the laboratory or in-situ, a simpler test may be needed instead of the slump test; the fall cone test was proposed as a substitute. In this paper, the correlation between the slump value obtained from the slump test and the cone penetration depth obtained from the proposed fall cone test was obtained. Test results showed that a very good correlation between two was observed; it means that the simpler fall cone test can be used to assess the suitability of the conditioned soils instead of the more cumbersome slump test.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.5
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• pp.357-371
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• 2023

In cable tunnel construction using TBM, the vertical shaft is an essential structure for entrance and exit of TBM equipment and power lines. Since a shaft penetrates the ground vertically, it often encounters rock mass. Blasting or rock splitting methods, which are mainly used to the rock excavation, cause public complaints due to the noise, vibration and road occupation. Therefore, mechanical excavation using vertical shaft excavation machine are considered as an alternative to the conventional methods. However, at the current level of technology, the vertical excavation machine has limitation in its performance when applied for high strength rock with a compressive strength of more than 120 MPa. In this study, the potential utilization of waterjet technology as an excavation assistance method was investigated to improve mechanical excavation performance in the hard rock formations. Rock cutting experiments were conducted to verify the cutting performance of the abrasive waterjet. Based on the experimental result, it was found that ensuring excavation performance with respect to changing in ground conditions can be achieved by adjusting waterjet parameters such as standoff distance, traverse speed and water pressure. In addition, based on the relationship between excavation performance, uniaxial compressive strength and RQD, it was suggested that excavation performance could be improved by artificially creating joints using the abrasive waterjet. It is expected that these research results can be utilized as fundamental data for the introduction of vertical shaft excavation machines in the future.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.3
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• pp.255-280
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• 2024

If there are concerns about the stability of segment lining due to section deficiency or large deformation in shield TBM tunnel, reinforcement can be done through ground grouting outside the tunnel or by using steel plate reinforcement, ring beam reinforcement, or inner double layer lining inside the tunnel. Traditional analyses of shield TBM tunnels have been conducted using a continuum method that does not consider the segmented nature of segment lining. This study investigates the reinforcement mechanism for double layer reinforced sections with internal steel linings. By improving the modeling of segment lining, this study applies Break-joint mode (BJM), which considers the segmented characteristics of segment lining, to analyze the deformation characteristics of double layer reinforced sections. The results indicate that the existing concrete segment lining functioned similarly to ground reinforcement around the tunnel, rather than distribution the load. In general, both the BJM model considering the segmentation of segment lining and the continuum rigid method were similar deformation shapes and stress distributions of the lining under load. However, in terms of deformation, when the load strength exceeded the threshold, the deformation patterns of the two models differed.