• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.837-845
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• 2013

An airlift pump can be used to pump liquids and sediments within itself, which cannot easily be pumped up by a conventional method, by using the airlift effect. This characteristic of the airlift pump can be exploited in a DCFC (Direct Carbon Fuel Cell) so that molten fuel with high temperature may be carried or transported. The basic characteristics of airlift are investigated. A simple system is constructed, where the reservoir is filled with water, a tube is inserted, and air is supplied from the bottom of the tube. Then, water is lifted and its flow rate is measured. Bubble patterns in the tube are observed in a range of air flow rates with the parameters of the tube diameter and submergence ratio, leading to four distinct regimes. The pumping performance is predicted, and the correlation between the supplied gas flow rate and the induced flow rate of water is found.

• Korean Journal of Ichthyology
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• v.29 no.1
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• pp.62-68
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• 2017

The Alaska pollock (Gadus chalcogrammus) belongs to the family Gadidae; it is a cold water fish, and has been developed as a novel aquaculture species in Korea. In this study, we describe ongoing surveillance for aquatic animal pathogens based on growth stages. We investigated bacterial flora in rearing water, and monitored pathogens; we also analyzed histopathological traits of abnormal fish. In rearing water, the total bacterial counts were $2.1{\times}10^3cfu/mL$ and Vibrio spp. (52%) were predominant in the larvae stage. In the juvenile and adult stages, the total bacterial counts were $3.4{\times}10^3$ and $3.2{\times}10^2cfu/mL$, respectively (with Pseudomonas sp. as the predominant species; 90% and 52%). This result revealed that the bacterial flora in rearing water changed depending on the feeding types. No virulent-bacteria or problematic viruses (VHSV, viral hemorrhagic septicemia virus; NNV, nervous necrosis virus; MBV, marine birnavirus) were detected from outwardly healthy fish using either culture or PCR assay. Some juveniles (less than 5%) had gas bubbles on the gill lamellae, degeneration of the corneal epithelium, and choroid gland degeneration, suggesting that these symptoms were caused by external injury and secondary infection by opportunistic bacteria. Disease management is important to cope with disease emergence in the novel aquaculture species Alaska pollock.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.7
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• pp.687-692
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• 2015

A mold design for in-mold coating was developed to achieve simultaneous coating and injection molding of an automotive armrest. The developed mold includes one core and two cavities which are composed of a substrate cavity and a coating cavity. The core was attached to a movable plate and two cavities were mounted on a plate sliding in a stationary plate. In a two-step process, the part was first injection molded and subsequently, with the aid of a sliding table, was transferred to a second cavity. The materials used were PC/ABS for substrate and two-component polyurethane for coating. The experiments were conducted by changing the flow rate to investigate mixing characteristics. As the flow rate increased, the mixing improved. Additionally, the bubbles appeared over the substrate surface decreased with an increase of the weight of injected coating material.

• Journal of the Economic Geographical Society of Korea
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• v.18 no.2
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• pp.206-223
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• 2015

Korea government has established 67 agri-food clusters for 10 years. In recent years, the criticism of this policy has significantly increased due to trials and errors. The purpose of this study is to suggest some policy implications for the focal firm and governance mechanism through the case study of Muan Loess Sweet Potato Cluster. The concept of netchain was used as an analysis framework. Muan Loess Sweet Potato Cluster doesn't operate an integrated production organization and focal firm doesn't exercise its influence as well. The cluster agency, focal firm of Cluster, is important for a Agri-food Cluster to grow continuously. it must have a great influence on organizing networks and an enough capacity for forming coordination mechanism. Also, Local governments must actively be involved in the network formation and coordination and inform the vision and plan for development.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1177-1184
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• 2011

Gas-to-Solid (GTS) technology is composed of three stages: hydrate production, transportation, and regasification. For efficient operation of regasification plants, it is crucial to predict the temperature and flow rate of hot water necessary to dissociate the hydrate pellets. Dissociated gas escaping from the pellet surface, when in contact with hot water, will alter the flow field and consequently alter the heat transfer rate. Methane hydrate pellet dissociation characteristics in low- to moderatetemperature water were investigated by taking images of the changes in the hydrate pellets' shapes in a pressurized reactor and measuring the total time required for complete melting of the pellets. The effects of water temperature, hydrate conversion rate, and flow speed on the dissociation completion time were also investigated. Bubbling gas released from the pellet surface induced a secondary flow that enhanced the heat transfer rate and thus decreased the dissociation time. It was also found that a considerable flow rate was needed to significantly decrease the dissociation time.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.712-712
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• 2012

하 폐수 처리방류수를 물리적, 화학적 그리고 생물학적 기술을 이용하여 처리한 후 재활용수로 이용하고자 하는 새로운 노력들이 진행되고 있지만 국내의 경우 방류수 재활용 기술과 처리수의 재이용에 대한 평가기술이 선진국에 비해 초기 단계에 있어 이 분야에 대한 적극적인 기술개발이 요구된다. 막 분리 기술을 이용한 처리 수는 소독 등의 추가적인 처리 없이 살수용수나 수경용수로 이용이 가능하며, 잔류염소를 유지시킬 경우 화장실 세정용수로의 이용도 가능하며, 또한 후처리 기술을 조합하면 고급 공업용수 등으로 사용가능하므로 선진기술로서 수요조건에 맞게 전 후 처리를 조합한 수요자 맞춤형 재이용수 공정기술을 개발할 필요가 있다. 이에 효율적인 하 폐수 재이용을 이용하여 농업용수(축산 음용수, 첨단 수출원예용수, 첨단 농업용수, 농산업 클러스터 복합 곡물 용수), 원예용수(원예단지), 공업용수 등의 다양한 용도에 활용 가능한 수요자 맞춤형 모듈 및 공정 개발을 수행하였다. 개발된 공정은 AOP 및 막 세정 시스템을 이용한 새로운 공정으로, AOP 시스템은 전기 이온 모듈을 통해 OH 라디칼을 생성 및 염분 제거 효율을 극대화 하여 오염 물질을 산화시키는 공정이며, FDA 시스템은 탁도가 높은 원수가 과다 유입 될 경우 후단 여과 막의 부하를 줄이는 역할을 하며, 부유 물질을 여과 시킨다. 막 세정 시스템은 미세 입자를 구성된 기포를 이용하여 눈에 보이지 않는 곳 까지 세척하며, 살균 작용을 하며, 분리 막의 성능을 증대 시킨다. 이어 UF 분리 막 시스템은 원수의 미세불순물, 박테리아, 스케일 물질 등을 제거하며, NF 시스템을 통하여 미립자, 박테리아 유기 화합물 및 2가 염 제거를 하여 재이용수를 생산하는 공정을 개발하였다. 개발된 수요자 맞춤형 공정은 하수 재이용 기술의 이용 목적 및 수요자별로 맞춤형으로 운영이 가능하며, 개발된 세척 기술은 분리 막 세정 유지관리비 및 에너지를 저감 할 수 있으며, 현장 적용의 실증화 과정을 거쳐 공정 기술을 신뢰도를 향상하고, 보유 기술을 수요자 맞춤형으로 업그레이드함으로써 기술의 경쟁력 및 고품질의 하수 재이용 기술의 새로운 방향을 제시 할 수 있을 것으로 판단된다.

• The Journal of the Petrological Society of Korea
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• v.18 no.4
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• pp.337-348
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• 2009

Clear and homogeneous glass inclusions are well preserved at the rim of the quartz phenocrysts of tuff from Sunshin epithermal Au deposit, Haenam, although the host rocks experienced extensive silicification and argillic alteration. Glass inclusion vary in size from $5\;{\mu}m$ to larger than $200\;{\mu}m$ consisting of glass(60~80 vol%) + vapor bubble(15~30 vol%) $\pm$ daughter crystals(<10 vol%). Most of glass inclusions are cubic to rectangular in shape, indicating that the host quartz grew in the stability field of $\beta$-quartz. All the glass inclusions appear to be primary. Glass inclusions are composed of highly evolved high-K calc-alkaline rhyolites, which can represent the final liquidus phase of the magma system. The $Au_2O_3$ concentration (<0.30 wt%) is trivial in the glass, indicating there was no enrichment in the final residual melt. Textural characteristics suggest that magma was water-saturated shortly before or during the eruption. $H_2O$ content of the glass (ca. 2-4 wt%) suggests a water saturation pressure($P_{H2O}$) of about 300-900 bars. This pressure implies a minimum depth of 0.8-2.5 km for the magma chamber.

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.286-293
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• 2005

An interpretation on the solid circulation characteristics in a fluidized-bed process has been carried out as a first step to simulate the dry entrained-bed absorption and bubbling-bed regeneration system for $CO_2$ removal from flue gas. A particle population balance has been developed to determine the solid flow rates and particle size distributions in the process. Effects of principal process parameters have been discussed in a laboratory scale process (absorption column: 25 mm i.d., 6 m in height; regeneration column: 0.1 m i.d., 1.2 m in height). The particle size distributions in absorption and regeneration columns were nearly the same. As gas velocity or static bed height in the absorption column increased, soild circulation rate and feed rate of fresh sorbent increased, however, mean particle diameter decreased in the absorption column. As cut diameter of the cyclone of the absorption column increased, solid circulation rate decreased, whereas feed rate of fresh sorbent and mean particle diameter in the absorption column increased. As attrition coefficient of sorbent particle increased, solid circulation rate and feed rate of fresh sorbent increased but mean particle diameter in the absorption column decreased.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.5
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• pp.499-507
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• 2004

We have studied tile detection techniques, which can determine the location and the weight of an intruder into infrastructure, by using fiber-optic ROTDR (Rayleigh optical time domain reflectometry) sensor and fiber-optic BOTDA (Brillouin Optical time domain analysis) sensor, which can use an optical fiber longer than that of ROTDR sensor Fiber-optic sensing plates of ROTDR sensor, which arc buried in sand, were prepared to respond the intruder effects. The signal of ROTDR was analyzed to confirm the detection performance. The constructed ROTDR could be used up to 10km at the pulse width of 30ns. The location error was less than 2 m and the weight could be detected as 4 grades, such as 20kgf, 40kgf, 60kgf and 80kgf. Also, fiber optic BOTDA sensor was developed to be able to detect intrusion effect through an optical fiber of tells of kilometers longer than ROTDR sensor. fiber-optic BOTDA sensor was constructed with 1 laser diode and 2 electro-optic modulators. The intrusion detection experiment was peformed by the strain inducing set-up installed on an optical table to simulate all intrusion effect. In the result of this experiment, the intrusion effort was well detected as the distance resolution of 3m through the fiber length of about 4.81km during 1.5 seconds.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.3
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• pp.214-220
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• 2001

The clinical application of the three-dimensional radiographic technique had been limited to standard Broadbent-Bolton cephalometer with biplanar stereoradiography. We developed a new method for compensating the error of head position in ordinary non-biplanar cephalostat. It became to possible to use the three dimensional cephalogram commonly in clinical bases. 1. The method of methemetical compensation of head positioning error in non-biplanar condition was evaluated with dry skull. The error of the method of first and the second trial was $0.46{\pm}1.21$, $0.33{\pm}0.90mm$, which means the error of the head positioning correction in conventional cephalogram was within clinical acceptance. 2. The reproducibility of this system for clinical application was 0.54 mm ($-2.99{\sim}2.26mm$) which defines the absolute mean difference of the first and second trial. Compare to the The landmark identification error $1.2{\pm}1.6mm$, the error of the measurement was within the range of landmark identification error. The result indicates the adequate clinical accuracy of the computation of three-dimensional coordinates by compensation of the error of the head position in ordinary non-biplanar cephalostat.