• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.211-217
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• 2019

The three major inventions of Jeju include the field wall of Kim Koo Pan Gwan in 1234, Jeongnang in the custom of grazing the people of Jeju, and Olleh in the tomb of Munbang-gui in 1406. Field wall, Oedam from the stone and the stone of numerical play, made Koendang, a friendship society. Even with a typhoon that is more than 30m/s, the Koendang which is about 1.5m high, will not collapse. Similarly, the main family networks of Jeju society do not collapse under any difficulties situation. When building a field wall, two stones, which are under the ground, are placed side by side, and the upper left stone is placed on top and the upper right stone is attached regularly. One stone or two stone is attached from the bottom to the top, and when a stone is small or large, a flat field is formed in one space. The Family networks is close to the grandfather, grandmother, father, mother, and me, and the distant kin represents a horizontal relationship. The field wall is a vertical relationship that builds up from bottom to top of the vertical relation, while the Koendang is a horizontal relationship where blood is distributed to the grandson of his upper grandparents. This paper proves by a non-orthogonal symmetric weighted Hadamard matrix of whether the stone in the middle of a field wall has large stones (small).

• Explosives and Blasting
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• v.39 no.3
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• pp.15-23
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• 2021

Ventilation shafts are pathways in mines and tunnels for the removal of dust or smoke during underground space construction and operation. In mines, blasting with long blast holes is preferred for the excavation of a ventilation shaft in the 10~20m long crown pillar section. In this case, the bottom part of the blast hole is completely drilled in order to determine the drilling error, and this causes a problem of lowering the explosive charge and blasting efficiency. It is possible to solve the problem of explosive loading and to increase the blast efficiency by covering the curb of the blasthole by using stemming material. In this study, simulations for the blasting of a ventilation shaft were performed with various stemming lengths and the blasthole diameters(45, 76mm) using AUTODYN 2D SPH(Smooth particle hydrodynamics) analysis technique. Also the optimal bottom stemming column was derived by checking the size of the boulder and burden line according to blasting. Analysis result, blasting efficiency is lessened in case of stemming length less than 30cm and the optimal length of the stemming material should be 30cm or higher to achieve high efficiency of blasting.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.86-94
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• 2019

This paper describes the development of unmanned vehicle remote control system which is configured with steering and accelerating/braking hardware to improve the sense of reality and safety of control. Generally, in these case of the remote control system, a joystick-type device is used for steering and accelerating/braking control of unmanned vehicle in most cases. Other systems have been developing using simple steering wheel, but there is no function of that feedback the feeling of driving situation to users and it mostly doesn't include the accelerating/braking control hardware. The technology of feedback means that a reproducing the feeling of current driving situation through steering and accelerating/braking hardware when driving a vehicle in person. In addition to studying feedback technologies that reduce unfamiliarity in remote control of unmanned vehicles, it is necessary to develop the remote control system with hardware that can improve sense of reality. Therefore, in this study, the reliable remote control system is developed and required system specification is defined for applying force-feedback haptic control technology developed through previous research. The system consists of a steering-wheel module similar to a normal vehicle and an accelerating/braking pedal module with actuators to operate by feedback commands. In addition, the software environment configured by CAN communication to send feedback commands to each modules. To verify the reliability of the remote control system, the force-feedback haptic control algorithms developed through previous research were applied, to assess the behavior of the algorithms in each situation.

• The Journal of the Korea Contents Association
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• v.19 no.2
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• pp.259-268
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• 2019

Dengue virus is a typical mosquito-borne virus, and the half of the world's population is exposed to infection. Dengue virus causes relatively mild symptoms such as dengue fever. However, when not treated properly, it is known to cause severe symptoms such as dengue hemorrhagic fever and dengue shock syndrome with a mortality rate of over 20%. Development of dengue virus detection technology is very important because it is reported that early diagnosis of dengue fever can lower the mortality rate to less than 1%. In this study, patent search related to dengue virus detection technology was conducted in Korea, USA, Europe, Japan, and China. The quantitative analysis of 69 validated patents from the searched patents was conducted by country, year, and patent holder. In addition, in-depth analysis was carried out by classifying into three categories: molecular diagnostics, immuno-diagnostics, and cell culture-based diagnostics from all validated patents. From these results, we analyzed the patent trend related to dengue virus detection and dengue fever diagnosis technology and discussed the features and limitations of molecular diagnostics and immuno-diagnostics at present level. Furthermore, we discussed the direction of technology development and future prospects to overcome limitations.

• Explosives and Blasting
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• v.36 no.4
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• pp.35-47
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• 2018

In this study, several concrete-block blast tests and AUTODYN numerical analyses were conducted to analyze the effects of different stemming and coupling materials on explosion results. Air, sand, and polymer gel were used as both the stemming and coupling materials. The stemming and coupling effects of these materials were compared with those of the full-charge condition. Soil-covered or buried concrete blocks were used for field crater tests. It was found from the concrete block tests and numerical analyses that both the crater size and the peak pressure around the blast hole were higher when the polymer gel was used than when the sand and the decoupling condition were used. The numerical analyses revealed the same trend as those of the field tests. Pressure peaks in concrete block models were calculated to be 37, 30, and 16 MPa, respectively, for the cases of the polymer gel, sand, and no stemming and decoupling condition. The pressure peak was 52 MPa in the case of full-charge condition, which was the highest pressure. But the damage area for the case was smaller than that obtained from the use of polymer gel. Full-charge was also used as a reference test.

• Explosives and Blasting
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• v.36 no.4
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• pp.1-8
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• 2018

This numerical study was intended to evaluate the applicability of the half charge blasting to mining and tunnelling. The half charge blasting is a method that two separate rounds are sequentially blasted for the rock burdens in which long blast holes have already been drilled at one operation. The aim of the method is to decrease the construction cost and period in mining and tunnelling projects as well as to increase the blasting efficiency. Several numerical analyses were conducted by using the Euler-Lagrange solver on ANSYS AUTODYN to identify the effects of the suggested method on the blasting results in underground excavations. The overall performance of the suggested method was also compared to an ordinary blasting method. The analysis model was comprised of the Eulerian parts (explosive, air, and stemming materials) and the Lagrangian parts (rock material). As a result, it was found that, owing to the air decks formed in the bottom parts of the long blast holes, the first round of the suggested method presented a higher shock pressure and particle velocities in the vicinity of the blast holes compared to the ordinary blasting method.

• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.305-313
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• 2011

Fertilization is essential to seedling production in nursery culture, but excessive fertilization can contaminate surface and ground water around the nursery. The objective of this study was to find optimal fertilization practice of container seedling production for reducing soil and water contamination around the nursery without compromising seedling quality. This study was conducted to investigate growth performance, photosynthesis, chlorophyll fluorescence, and chlorophyll contents of Liriodendron tulipifera growing under three different fertilization treatments (Constant rate, Three-stage rate, and Exponential rate fertilization). Root collar diameter, height, and biomass of L. tulipifera were the highest at Constant treatment. Like growth performance, seedling quality index (SQI) were higher at Constant than at other treatments, but not significantly different among treatments. L. tulipifera showed good photosynthetic capacity at all treatments. Photochemical efficiency and chlorophyll contents were significantly lower at Exponential than at other treatments. Therefore, Exponential fertilization which is 50% fertilizer of other treatments would maximize seedling growth and minimize nutrient loss.

• Economic and Environmental Geology
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• v.54 no.4
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• pp.457-464
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• 2021

The objectives of this study were to analyze of soil chemical characteristics of abandoned coal mine forest rehabilitation areas in Gangwon-do. The study sites were 8 areas and the investigations were performed 11 times according to elapsed time. Soil characteristics were soil pH, TOC, Total-N, C/N ratio, and Av. P₂O₅. Soil pH and Av. P₂O₅ were decreased according to elapsed time after forest rehabilitation, while TOC, Total-N, and C/N ratio increased. TOC and Total-N arrived at quality requirements of covering soil for forest rehabilitation in abandoned coal mine area passed 10 years after forest rehabilitation, while soil pH became lower than that. Therefore, it needs long-term monitoring of soil chemical characteristics after the forest rehabilitation and to establish post management.

• Economic and Environmental Geology
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• v.54 no.4
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• pp.483-494
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• 2021

This study was carried out to investigate the feasibility of reducing clean cover soil using a flooded column test in arsenic-contaminated farmland reclamation of abandoned coal mine area that shows generally low or about worrisome level (25 mg/kg) of Korea soil environment conservation act unlike abandoned metal mine. During the monitoring period of soil solution for 4 months, chemical properties (pH, EC, ORP, Fe, Mn, Ca, and As) in each layer (clean soil cover and contaminated/stabilized soil) showed different variation. This result revealed that soil solution in stabilized or contaminated soil rarely affected that in cover soil. Whether stabilized or not, arsenic concentrations in the rice roots grown in the soil covers with the thickness of 40 cm decreased by 98% in compared with the that grown in the control soil. In case of the soil covers with 20 cm thickness on stabilized soil, it decreased by 80% and this was 22 percentage point higher than when the soil of lower layer was not stabilized. Thus, reducing clean cover soil could be possible in contaminated farmland soil reclamation if appropriate stabilization of contaminated soil is carried.

• Tunnel and Underground Space
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• v.32 no.2
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• pp.160-172
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• 2022

The design regulations for simple explosive storage in Korea only stipulate standards for the materials and thickness of the wall of the structure because the amount of explosives that can be stored is small. There is concern about secondary damage during an internal explosion in a simple storage facility, and it is necessary to reexamine the current standards. The numerical analysis for the TNT 15 kg explosion inside the simple storage was carried out by setting the factors using the robust experimental design method. The displacement of the structure generated under the same time condition was analyzed, and the contribution was evaluated. The contribution of concrete thickness was the highest, and the contribution of concrete strength and rebar arrangement was lower than that of concrete thickness. The reinforcement diameter contributed extremely little to the displacement. The structural standards of the simple storage that are currently applied are insufficient on blast resistance, and it is necessary to present new design standards. Therefore, the design factor to be applied later analysis and actual experiments were taken into consideration. For the design variables, the thickness of the concrete was 15 cm considering the displacement, the concrete strength was selected as general concrete considering the inlet discharge pressure, the factor with the lowest average displacement was selected for the reinforcement arrangement and the diameter of the reinforcement, the factor with the smallest level was selected in consideration of economic feasibility because the difference in displacement was low.