• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.10 s.253
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• pp.982-986
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• 2006

It is well known that the surface tension forces can make a particle denser than water float when the size of the particle is of the order of 1 mm. This is deeply related to the basic mechanism enabling small insects to wander around on the pond surface and also to a newly emerging technology of self-assembly using capillary forces. For the quantitative understanding of this effect, we experimentally study the maximum density of a cylinder that can float on water and how fast the cylinder sinks when the density exceeds the maximum value. We compare our experimental results with the theoretical prediction and find good agreement between them.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.4
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• pp.36-44
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• 1997

This experiment was mainly performed with a mechanical treatment using ultrasound. We got the following conclusions : At seven minutes-ultrasonic treatment using nonionic surfactant, yield, brightness and residual ink contents were superior to other treatment, but several strength properties were decreased. On the other hand anionic surfactant was considerably low ink removal efficiency. For ultrasonic treatment using nonionic surfactant, yield and brightness were dropped when temperature was over 4$0^{\circ}C$, but were observed to be insensitive to the pulp consistency and flotation time. In the case of nonionic surfactant, tensile and burst strength were improved when ultrasonic treatment was used comparing to non-treatment, and nonionic surfactant was generally better than anionic surfactant in terms of tensile and burst strength regardless of ultrasound conditions. Several properties were decreased when anionic surfactant was used in comparison with nonionic surfactant except yield, therefore, anionic surfactant. was not proper to be used in this condition.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.10a
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• pp.119-123
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• 2011

The application of flexo printed ONP and OCC leads to brightness decrease of deinked stock in ONP recycling system. The largest problems are due to accumulation of flexo ink & introduction of brown fibers. All these are emphasized by variations in the amount of flexo printed ONP and OCC in recovered ONP stock. Most of the brightness problems caused by flexo ink can be helped and solved by applying a proper polyelectrolytes as coagulation agent and flocculation agent. This requires exact evaluation of sedimentation or dissolved air flotation potentials of flexo ink and polyelectrolytes. Effect of bleaching chemical (H2O2) addition level on the increase of brightness of OCC included stock has been investigated by lab scale test.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1995.11a
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• pp.42-49
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• 1995

석유에너지의 고갈을 앞두고 석탄에너지의 활용연구가 우리나라에서도 광범위하게 연구되어 왔다. 현재 국내에서 석탄(무연탄과 유연탄)은 발전용으로 대량 사용되고 있으며 이중에서 유연탄은 전량 수입에 의존하고 있다. 지리적으로 중국과 접하고 있는 우리나라의 경우 중국의 석탄 사용은 피할 수 없는 현실이며 지금도 상당량을 중국에서 수입하고 있다. 현재까지 우리나라에서는 비교적 저회분, 저유황분의 석탄만을 중국에서 수입하고 있다. 그러나 중국에서 점차 저유황탄의 생산이 줄어들고 있는 점을 감안할 때 앞으로는 고회분, 고유황탄의 수입이 필연적일 것으로 생각된다. 그러나 이 경우 우리는 SOx발생에 의한 환경오염에 대한 대비책이 있어야 하며 이와 관련하여 석탄전처리(Coal Cleaning)기술은 매우 중요하다.

• Journal of Korean Society of Water and Wastewater
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• v.17 no.4
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• pp.528-533
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• 2003

Bubble size is one of the most important parameters affecting DAF (Dissolved-Air-Flotation) process. It is generally known that small bubbles are preferred. However, the fact seems to be based on the particle removal efficiency at contact zone only, without considering separation zone. Besides, the effect of bubble size on the overall DAF process has not been fully investigated yet. Therefore, the effect of bubble size on collision efficiency, collision chances, and surface loading rate is calculated using theoretical models, and the results are discussed in this paper.

• Journal of Forest and Environmental Science
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• v.23 no.2
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• pp.73-78
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• 2007

Ultrasonic deinkings of white ledger were carried out to confirm whether the ink removal efficiency and pulp qualities can be improved by the ultrasonic deinking. The effects of conventional pulping and ultrasonic treatment of white ledger on the ink particle size distribution and ink removal coefficient were compared. The physical properties of paper, energy consumption and effluent qualities were measured. The ultrasonic treatment of white ledger resulted in the ink particle size distribution suitable for flotation. The ink removal efficiency, brightness, breaking length and effluent quality were improved by the ultrasonic deinking. It is expected that the competitiveness of ultrasonic deinking system can be improved by the optimization of treatment condition.

• Journal of the Korean Society of Marine Environment & Safety
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• v.2 no.1
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• pp.67-75
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• 1996

An innovative batch electrolytic system consisted of electrolytic basin, which was equipped with DSA(Dimensionally Stable Anode) type insoluble electrode, Ti/IrO2 anode and H-C metal cathode, and flotation separator was developed for the efficient treatment of shipboard emulsified oily wastewater. The electorod cleance and current density of elecrolytic basin to ensure maximum treatment efficiency of oily wastewater was evaluated as 6 mm, 3 A/dm3, respectively. The electrolytic efficiency of oily wastewater was affected by the operationtemperature, and it means that the temperature controller to ensure the stabiity of the process is required. The conductivity in the electrolytic basin was increased with the percentage of sea water in the oily wastewater, and over 90% of treatment efficiency of oily wastewater could be obtained at 7% of sea water. The oil removal rate was increased according to the increase of the quantity of electricity, and the maximum value of electrilyic rate constant was 288 mgoil/A.min. The information obtained from this study might be used for development of an efficient continuous electrolytic system treating the emulsified oily wastewater.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.203-207
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• 2003

As the upending is one of the critical steps in the installation of offshore structure, datail procedure of upending operation is studied in the paper. For larger offshore structure installation, launching method is often applied. However after launching, the upending process is to be followed. To ensure successful upending operation, datail process is analysed considering various factors affecting on the operation including reserved buoyancy, free flotation position, seabed clearance, ballast and hook load. To investigate the influence of each factor on the procedure, twelve numerical jacket models with various dimensions are simulated and studied. From the study, it is revealed that the increase of buoyance and decrease of self weight generate a large seabed clearance. The law seabed clearance during flooding creates higher hook load and height. The paper also introduces a guideline for the related structure design and construction with the effects of contribution factors in the upending operation.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.4
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• pp.118-125
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• 1997

Conventional sedimentation method has some limitations for turbidity removal in water treatment because drinking water sources are getting polluted. Removal rates of turbidity using DAF and sedimentation process were compared for various water conditions to know whether DAF is effective to improve sedimentation process. Water samples were clay(gravity 2.65) water 100mg/l, H raw water, mixed water of H raw water and clay 100mg/l, and mixed water of HA(Humic Acid) 5mg/l and clay 100mg/l. Other parameters were temperature, coagulants(Alum, $FeCl_3$), and treatment time. Water temperature greatly affected in removal rates of turbidity for sedimentation and DAF. Generally DAF was more effective in removal rates of turbidity than sedimentation at the same experimental condition. Removal rates of $UV_{254}$ were high to over 90%, and independent of temperature and coagulant.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.4
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• pp.34-41
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• 2003

The effect of wettability of deinking agents which formed with various nonionic surfactants against the pulp fibers and ink particles were studied, And the effect of flotation processes on the deinking were also investigated. The wettabilities of the deinking agents against the water and ink particles were measured by Washburn tube and sessile drop techniques, respectively. As the water absorption increased (i.e., hydrophilicity increased), the ink removal increased, which indicates that the ink removal is strongly affected by the detachment process due to the swelling of the pulp. Also, when the contact angle of air/ink/deinking agent increased, the hydrophobicity of the ink particles increased, the efficiency of the ink removal and the brightness increased.