• Explosives and Blasting
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• v.38 no.4
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• pp.16-25
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• 2020

Multi-setting smart-investigation of the ground and large uncharged hole boring (MSP) method to reduce the blast-induced vibration in a tunnel excavation is carried out over 50m of long-distance boring in a horizontal direction and thus has been accompanied by deviations in boring alignment because of the heavy and one-directional rotation of the rod. Therefore, the deviation has been adjusted through the boring machine's variable setting rely on the previous construction records and expert's experience. However, the geological characteristics, machine conditions, and inexperienced workers have caused significant deviation from the target alignment. The excessive deviation from the boring target may cause a delay in the construction schedule and economic losses. A deep learning-based prediction model has been developed to discover an ideal initial setting of the MSP machine. Dropout, early stopping, pre-training techniques have been employed to prevent overfitting in the training phase and, significantly improved the prediction results. These results showed the high possibility of developing the model to suggest the boring machine's optimum initial setting. We expect that optimized setting guidelines can be further developed through the continuous addition of the data and the additional consideration of the other factors.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.1
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• pp.113-119
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• 2013

To develop a new nuclear fuel, it needs to make a test fuel rod and carry out burn-up test in the test loop of a research reactor to check the irradiation characteristics of the nuclear fuel. At that time, several sensors such as thermocouples, LVDTs and SPNDs are needed to be attached in and out of the fuel rod and connect them with instrumentation cables. Then, the instrumentation cables deliver the signals measured by the sensors to the measuring device located outside of the reactor pool. In particular, to install a thermocouple in a fuel rod, it needs to drill off holes on the alumina blocks and sintered $UO_2$ pellets. However, because the hardness of a sintered $UO_2$ pellet is 700 Hv (or HRC 61) and that of an alumina block is 1480 Hv, a special drilling machine which adapts a diamond coated drill bit had developed. In this study, several case experiments have been carried out to find an optimal drilling condition of the drilling machine. And, using the optimal drilling condition, minimum numbers of the holes that a drill bit can drill off are verified.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.6
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• pp.603-611
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• 2016

Research and development of mineral-resource-related products has progressed with the increased need to develop mineral resources. The DTH hammer is a resultant product. However, owing to particular work conditions of underground drilling, it is difficult to obtain direct data on the DTH hammer. A DTH drill rig requires a significant amount of money and time for actual testing. This thesis aimed to resolve this problem by using CAE. In a previous paper, the structure of the DTH hammer and its movement were analyzed, and a standard model based on simulation was proposed. Then, experimentation and comparison verification were conducted. In this paper, by using an experimental design method, we derived a control factor of the impact force and efficiency of the DTH hammer and attempted to optimize the design. As a result, the impact energy increased by 14.9%, and the efficiency increased by 3.3%.

• Tunnel and Underground Space
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• v.22 no.4
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• pp.257-265
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• 2012

In this study, a series of CFD (Computational Fluid Dynamics) simulations carried out to evaluate the optimum design model of the internal flow path of drill bit. The Star-CCM+ code was adopted to simulate the multi-phase discharge flow of rock particles and flushing air during a drilling process. The input parameters for the flow simulation of rock particles and air were obtained from the in-situ drilling test results. After the three design factors were determined, the experimental design method (Taguchi method) was utilized to evaluate the optimum value of each factor.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.2
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• pp.8-15
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• 2006

To reduce costs and address other practical concern related to architectural lighting, we have been involved in various aspects of advanced daylighting design and control. If we look toward future building trends, we see that the advanced has already successfully deployed such complex lighting control systems. This paper takes a broad view of what advanced manufacturers have done to develop energy efficient lighting control technologies such as sensors, lumen maintenance, time of day scheduling, peak demand reduction and so forth. First of all strategies, daylighting controls would also need to be commissioned to respond to the specific daylighting signature of the zone. To translate the daylight in term of the amount of energy savings, an electric lighting system is designed and automatic on-off control system integrated with the contribution of daylighting has been applied to the operating of the artificial lighting. The lighting analysis program, Lumen-Micro predicts the optimal layout of conventional fluorescent and incandescent lighting fixtures to meet the designed lighting level and calculates unit power density, which translates the demanded amount of lighting energy.

• Horticultural Science & Technology
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• v.33 no.3
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• pp.375-382
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• 2015

A controlled atmosphere (CA) regimen was optimized during 3 consecutive harvest seasons as the basis of practical modified atmosphere packaging (MAP) storage for quality maintenance and extension of storage potential of fresh Ligularia fischeri leaves. Leaves were harvested in April or May and forced-air cooled to $4^{\circ}C$ before punch-hole MAP (control, where gas concentrations were same as air) and CA treatments. CA regimens adjusted stepwise during 3 experimental years were: 1 and 3% $O_2$, respectively combined with 5 and 10% $CO_2$ in the first year, 3% $O_2$ fixed in combination with 0, 2.5, and 5% $CO_2$ in the second year, and 3% $O_2$ fixed in combination with 2.5 and 5% $CO_2$ in the third year. In the first year, higher incidence of black discoloration was observed with the reduction of respiration under 10% $CO_2$ CA conditions regardless of $O_2$ levels at 1 or 3%. In the second and third year, the incidence of the disorder seemed not to be clearly relevant to CA conditions showing slightly higher incidence only after 4- or 5-week storage + 5-day shelf life. Although texture and appearance quality were maintained better under the 3% $O_2$ + 2.5% $CO_2$condition after 4-week storage + 5-day shelf life, effects of CA on the extension of storage period was slight. Overall results indicated that Ligularia fischeri leaves are very susceptible to $CO_2$ injury. $CO_2$ concentration should be adjusted below 2.5% for safe and effective CA or MAP storage to maintain quality even during short-term storage.