• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.83-90
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• 2018

This paper introduces a innovative diamond wire saw cutting technology and its experimental verification that can be utilized for cutting heavy structures. While conventional diamond wire saw cutting technologies such as water cooled cutting method and dry cutting method cause severe environmental problems due to generating massive concrete sludge or dust scattering, the proposed method can eliminate those problems considerably. Through extensive experiments using heavy structure test bed and real bridge pier structure, comprehensive analysis and comparative evaluation about various cutting methods were performed. As a result, the innovative diamond wire saw cutting method could achieve a similar cutting and cooling performance to the water cooled cutting method without generating concrete sludge and it showed an improved cutting and cooling performance to the dry cutting method without dust scattering. Consequently it is confirmed that the suggested cutting technology can be a promising environment-friendly alternative in the field of heavy structure dismantling.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.102-103
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• 2000

화학레이저는 화학연료의 반응에서 생성되는 막대한 화학에너지를 이용하여 레이저를 발생시키며, 반응하는 화학연료의 양에 따라 수천 kW의 고출력을 낼 수 있는 가장 강력한 레이저이다. 화학레이저인 Chemical Oxygen-Iodine Laser(COIL)는 염소기체(Cl$_2$)를 염기성 과산화수소수 용액과 반응시켜 고에너지의 여기산소(O$_2$($^1$$\Delta$))를 생성시키고 여기산소가 다시 요오드 원자와 반응하면서 1.3 $mu extrm{m}$ 파장의 레이저를 발생시킨다.(1)-(2) 이와같은 COIL 레이저는 발진효율이 높고 포화 강도가 높아 수십 kW 급의 고출력이 용이하게 이루어 질 수 있으며 광섬유 전송시 광손실이 가장 적어 레이저 빔의 원격 전송에 의한 재료가공에 적합한 레이저이다. 가공용레이저로 많이 사용하는 $CO_2$ 레이저에 비해 발진 파장이 짧으므로 재료의 광흡수율이 높아 일반 산업분야의 용접/절단에서 기존의 $CO_2$ 레이저를 대체할 것으로 기대되는 상용성이 큰 레이저이다.(3)-(4) 또한 COIL은 우수한 집속 특성을 유지하면서도 고출력의 개발이 가능하다. 이미 외국에서는 비록 단시간 동안 동작하지만 수백 kW급이 실현되었으며 수천 kW 급 고출력 항공기탑재형 COIL 이 수백 km의 거리에서 미사일을 요격하기위해 지금 개발중에 있다.(5) 일반 산업용 광섬유에 의해 쉽게 전송되는 파장인 1.315 $\mu\textrm{m}$ 인 수십 kW 급 COIL 은 조선 등의 중공업산업용 및 원자력 제염/해체분야에서 다용도 기술로서 광범위하게 사용될 것이다. COIL은 다양한 재료와 다양한 두께의 구조물 절단, 표면처리 그리고 용접에도 이용될 수 있다. COIL의 산업화는 빠르게 발전하고 있으며 산업용으로써 장시간 연속사용이 가능한 20-30 kW급 시설이 곧 개발될 것으로 기대된다. 따라서 개발될 고출력 화학레이저가 앞으로 원자력시설의 해체시 작업자의 안전성 향상에 크게 기여할 수 있게 되었다.(6) 여기서는 화학레이저인 COIL 장치와 기본적인 원리, 그리고 염소유량에 따른 출력특성등을 살펴보기로 하겠다. (중략)

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.3
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• pp.331-337
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• 2018

The decommissioning of nuclear power plants is generally executed in five steps, including preparation, decontamination, cutting/demolition, waste disposal and environmental restoration. So, for efficient decommissioning of nuclear power plants, worker safety, effects compared to cost, minimization of waste, possibility of reuse, etc., shall be considered. Worker safety and measurement technology shall be secured to exert optimal efficiency of nuclear power plant decommissioning work, for which accurate measurement technology for systems and devices is necessary. Typical In-Situ methods for decommissioning of nuclear plants are CZT, Gamma Camera and ISOCS. This study used ISOCS, which can be applied during the decommissioning of a nuclear power plant site without collecting representative samples, to take measurements of the S/G Water Chamber. To validate the measurement values, Microshield and the GEANT4 code was used as the actual method were used for modeling, respectively. The comparison showed a difference of $1.0{\times}10^1Bq$, which indicates that it will be possible to reduce errors due to the influence of radiation in the natural environment and the precision of modeling. Based on the research results of this paper, accuracy and reliability of measurement values will be analyzed and the applicability of the direct measurement method during the decommissioning of NPPs will be assessed.

• Korean Journal of Microbiology
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• v.36 no.3
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• pp.181-186
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• 2000

The cellulosome of Clo.~tr~rlil~m tl\ulcornererfnocellum consistmg of 26 dfferent polypeptides contains calcium. The polypeptides dissociated when calcium was removed. Most of dockerill region in the catalytic polypeptides cleavcd during dmociation. The dissociated polypeptides were well separated by MonoQ column chromatography into CipA containing fraction, a fraction still complexed wit11 91 kDa (CelK-a). 60 IiDa and 57 kDa polypeptides, and fractious contailling mainly single polypeptide of 46 kDa (CelA-a) or 71 1d)a polypeptide (CelS-trj Most or the fractions hydrolyzed c~ystalliue cellulose The purified 71 kDa polypeptide was strictly dependent on calcium for crystalline cellulose hydvolyzing activities a1 $60^{\circ}C$~$70^{\circ}C$ but 46 kDa polypeptide was not. 46 M)a polypeptide digested cellodextri~~ as cellobiose or cellotriose unit, and glucose was produced together with cellobiose and cellotriose froln cellotetraosc. It seems that cellulosome produces final product, cellobiose, through coordinated ~qulation of activities of vannus subunits.

• Journal of Industrial Technology
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• v.24 no.B
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• pp.19-29
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• 2004

The demand for demolition of steel structures is recently increasing in Korea. Most of flexible linear-shaped charges(FLSC) for steel demolition are now imported from foreign countries. Some basic experiments have been studied to determine the optimum parameters of design for domestic development of FLSC. Domestic FLSC were used to check cutting of steel structures and other materials in this study. The result shows that domestic FLSC is very effective to cut steel structures.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.6
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• pp.1277-1285
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• 2015

It has been known that the conventional retaining wall system with timber lagging and H pile has several problems such as the irregular gap between H-piles, cutting or adding to standard timber, back fill over first step excavation, and especially break-down accident at the disjoint of wall system. In the practical excavation, these problems may lead to worker's accident and the inefficiency of construction economy. To solve the above problems, a new method using prefabricated retaining wall was proposed and verified. The characteristics of the new method is to replace timber wall as free-sliding steel-lagging and connector. To check its verification and application, laboratory tests such as bending strength, tensile strength, and fatigue strength were carried out. Also, a pilot test in the field and numerical simulations under various ground conditions were performed. From the researches, it is found that the prefabricated retaining wall plate can be superior to the conventional timber lagging plate in the strength. It is also found that the proposed methods can be effective in the reuse of retaining wall plate and safe in the disjoint of wall system. Finally, it is desired that the proposed method will be effective in the reduction of the imported timbers and helpful in the safety of retaining wall construction.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.4
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• pp.473-478
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• 2018

Radioactive aerosol generated in cutting and melting work during the NPP decommissioning process can cause internal exposure to body through workers' breath. Thus, it is necessary to assess worker internal exposure due to the radioactive aerosol during decommissioning. The actually measured value of the working environment is needed for accurate assessment of internal exposure, but if it is difficult to actually measure that value, the internal exposure dose can be estimated through recommended values such as the fraction of amount of intake and the size of particles suggested by the International Committee on Radiological Protection (ICRP). As for the selection of particle size, this study applied a value of $5{\mu}m$, which is the size of particles considering the worker recommended by the ICRP. As for the amount of generation, the amount of intake was estimated using data on the mass of aerosol generated in a melting facility at a site in Kozloduy, Bulgaria. In addition, using these data, this study calculated the level of radioactivity in the worker's body and stool and conducted an assessment of internal exposure using the BiDAS computer code. The internal exposure dose of Type M was 0.0341 mSv, that of Type S was 0.0909 mSv. The two types of absorption showed levels that were 0.17% and 0.45% of the domestic annual dose limit, respectively.

• Resources Recycling
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• v.12 no.3
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• pp.25-30
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• 2003

The synthesis of SiC used for the parts of the gas turbine and the heat exchanger, was carried out. In this study, wire cutting slurry of silicon wafer and the graphite rod of spent zinc-carbon battery were applied to the starting materials for the synthesis. The powders of Si or Si+SiC were obtained from the waste material by filtration, gravity separation and magnetic separation. Graphite powder was produced by dismantling, grinding and gravity separation from spent zinc-carbon battery. The synthesis of SiC could be completed from the mixture powders of Si and C or Si+SiC and C at the condition of equivalent ratio of Si and C, atmosphere of Ar or vacuum, temperature of above 1$600^{\circ}C$ and 2 hours reactions. The purity of synthesized Si-C was above 99%.

• Explosives and Blasting
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• v.39 no.1
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• pp.1-9
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• 2021

As the national economic growth and the rapid increase in industrial structures are aging, the demand for removing steel structures is increasing, and research on improving the penetration performance of the linear shape charge explosives. In the study, numerical analyses were performed on the effect of the type of explosive used in the self-made shape charging container and the initiation method on the cutting performance of the steel plate and the effect on the shaped explosive installed close to it. ANSYS LS-DYNA, which can analyze the large deformation problem of materials due to explosion, was used, and an ALE(Arbitrary-Lagrange-Eulerian) model was applied that enables interlocking analysis of gases, liquids, and solid.

• Resources Recycling
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• v.16 no.4
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• pp.3-9
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• 2007

Dismantlement of lithium primary batteries without explosion is required to recycle the lithium primary batteries which could be exploded by heating too much or crushing. In the present study, the optimum discharging condition was investigated to dismantle the batteries without explosion. When the batteries were discharged with $0.5kmol{\cdot}m^{-3}$ sulfuric acid, the batteries became inert after 4 days at $35^{\circ}C$ and after 1 day at $50^{\circ}C$, respectively. This result shows that higher temperature accelerates inert of the batteries. Because loss of metals recycled increases when the batteries are discharged only with the sulfuric acid, discharging process using acid solution and water was newly proposed. When the batteries were discharged with water during 24 hours after discharging with $0.5kmol{\cdot}m^{-3}$ sulfuric acid during 6 hours, the batteries discharged were dismantled without explosion. Because decrease in loss of metals was accomplished by new process, the recycling process of the batteries could become economic by the 2-step discharging process.