• Journal of Korean Society of Water and Wastewater
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• v.19 no.1
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• pp.25-30
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• 2005

In order to decrease the high costs of membrane process, we have tried to develop two alternatives to membrane; a cartridge type filter and a metal membrane were tested for the high permeation flux with low cost and low energy. This research mainly focused on three points; 1) operation with high permeation flux by using of a cartridge type filter and a metal membrane, 2) removals of the filterable organic materials (FOC) by pretreatments for the membrane fouling control, and 3) advanced wastewater treatment by SMBR process with intermittent aeration and high MLSS. An Intermittently aerated membrane bioreactor using a submerged micro filter (cartridge type) was applied in laboratory scale for the advanced wastewater treatment. To minimize membrane fouling, intermittent aeration was applied inside of the filter with $3.0kg_f/cm^2$. The experiments was conducted for 6 months with three different HRTs (8, 10, 12 hr) and high MLSS of 6,000 and 10,000mg/L. The filtration process could be operated up to 50 days with permeation flux of 500LMH. Regardless of the operating conditions, more than 95% of COD, BOD and SS were removed. Fast and complete nitrification was accomplished, and denitrification was appeared to be the rate-limiting step. More than 75% T-N could be removed due to the endogenous denitrification. T-P removal efficiency was increased to 80% under the condition of MLSS 10,000mg/L.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.5
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• pp.203-208
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• 2013

As smartphones are rapidly and widely spread, their applications request gradually larger computation power. Recently, in the personal computer, computing power of hardware has exceeded performance requirement of software sometimes. Computing power of smartphone, however, will not grow at the same pace as demand of applications because of form factor to seek thinner devices and power limitation by relatively slow technical progress of battery. Computation offloading is getting huge attention as one of solution for the problem. It has not commonly used technology in spite of advantages for performance and power consumption since the existing offloading frameworks are difficult for application developer to utilize. This paper presents an application developer-friendly offloading framework, named SorMob. Based on Aspect Oriented Programming model, SorMob provides a convenient environment for application development, and its performance was verified by comparing with the existing offloading framework.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.94-94
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• 2012

섬유산업은 원가 경쟁력 향상과 산업 고도화에 필요한 미래형 저에너지 염색가공 핵심 기술을 통한 고부가가치 섬유제품의 창출과 섬유산업의 선진화달성에 꾸준히 노력을 해 왔다. 염색가공업의 에너지 소비는 섬유산업에서 염색가공업이 연료 사용량의 77%, 전기사용량의 54%를 차지하여 섬유산업의 에너지절감을 위해서는 염색가공 공정에서의 에너지 절감이 가장 중요하다. 국내 염색가공 분야의 4백여 업체를 대상으로 실시한 애로 기술에 관한 설문 조사결과에 따르면 염색공업의 에너지 절약형 구조로의 전환을 위해서 가장 시급히 요구되는 우선기술 1순위는 에너지절약형 염색가공 공정기술로 에너지 절감의 필요성을 반영하고 있다. 효소(Enzyme)가 섬유산업에 도입되기 시작한 것은 면섬유의 호발에 아밀라제가 사용되기 시작하면서 부터이며, 최근 유럽선진국들의 강화된 환경규제와 눈부신 바이오테크놀러지(Biotechnology)의 발전에 기인하여 섬유산업에서 관심과 적용이 확대되고 있다. 섬유산업에서 효소적용의 장점은 효소 그 자체가 자연산물이기 때문에 생분해 되고 중성에 가까운 pH에서 반응하므로 처리액이 환경문제를 일으키지 않으며, 기질특이성을 가져 매우 선택적으로 반응하여 부반응으로 인한 섬유의 손상을 최소화 하는 효과를 들 수 있으며, 무엇보다 소량 저온반응으로 인한 에너지절감이 가장 큰 장점이라 할 수 있다. 실제 섬유산업에서는 전분호제를 제거하는 아밀라아제, 데님워싱 및 면섬유의 후가공에 사용하는 셀룰라아제, 표백 후 잔류하는 과산화수소를 제거하는 카탈라제 등을 적용하는 사례가 많아지고 있으며, 이 밖의 다양한 공정에 효소 이용연구가 활발히 진행되고 있다. 본 연구에서는 그 동안 섬유 업체에서 직물의 표면 잔털을 제거하여 매끄러운 외관과 선명한 색상을 재현하기위해 후가공으로 셀룰라아제를 이용했던 공정을 개선하여, 효소를 이용한 정련-Bio polishing-염색의 3공정을 1욕처리를 통해 기존 단독으로 진행되어진 기존제품과의 중량, 외관, 색상재현성, 정련성 등을 비교하여 에너지 절약형 공정기술의 효과를 극대화 해보았다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.629-634
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• 2011

A prestudy on expendable turbine engine for high-speed vehicle was conducted. The two possible mission profiles were established to decide the engine requirements and Design Point, and Design Point analysis was performed with the values of design parameter which were obtained from similar class engines and technical references. The results showed that Specific Net Thrust is 2599.4 ft/s and Specific Fuel Consumption is 1.483 lb/($lb^*h$) at the flight condition of Sea Level, Mach 1.2. It was also found through the performance analysis on the two possible mission profiles that major design parameters for determining Net Thrust were Turbine Inlet Temperature for low supersonic flight speed and Compressor Exit Temperature for high supersonic flight speed. In addition, simple turbojet engine with axial compressor, straight annular combustor, axial turbine and fixed throat area converge-diverge exhaust nozzle was proposed as the configuration of simple low cost light engine.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.321-327
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• 2008

Performance characteristics of the axi-symmetric supersonic exhaust diffuser (SED) with a second throat are numerically investigated. Computational strategy repeats those for a straight exhaust diffuser with zero-secondary flows. Renolds-Average Navier-Stokes equations with a standard ${\kappa}-{\varepsilon}$ turbulence model incorporated with standard wall function are solved to simulate the diffusing evolutions of the nozzle plume. The methodology is validated with accuracy. To predict the improvement of starting performance by second throat diffuser, diffuser characteristic curve due to the SED equipped with the second throat is speculated with respect to that of a straight area type as a function of nozzle stagnation pressure. Principal physics caused by the of the second throst is also addressed in terms of a second throat area ratio.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.152-157
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• 2005

Hypophosphatemia rickets, also known as Vitamin D-resistant rickets(VDRR) and refractory rickets, is a form of rickets which is resistant to the usual doses of vitamin D. VDRR is characterized by decreased renal tubular reabsorption of inorganic phosphate and is easily diagnosed by a normal blood calcium, hypophosphatemia, and slightly elevated alkaline phosphatase. Clinical features of Hypophosphatemia rickets included lateral bowing deformities of the legs, short stature, scoliosis, and enlargement of wrist and ankles. Dental finding in patient with VDRR were spontaneous dental abscesses in caries free teeth and other dental findings included delayed eruption, delayed apical closure, thin and hypoplastic enamel, absent or poorly defined lamina dura, enlarged pulp chambers, and numerous accessory canals and pulp horns that extend up and into the dentinoenamel junction. we reported the clinical feature and treatment of VDRR child who was referred from the department of pediatrics for early loss of primary teeth and its treatment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.442-446
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• 2000

The metal-oxide-semiconductor field-effect transistor(MOSFET) has undergone many changes in the last decade in response to the constant demand for increased speed, decreased power, and increased parking density. Therefore, it was interested in scaling theory, and full-band Monte Carlo device simulator has been used to study the effects of device scaling on hot carriers in different MOSFET structures. MOSFET structures investigated in this study include a conventional MOSFET with a single source/drain, implant a lightly-doped drain(LDD) MOSFET, and a MOSFET built on an epitaxial layer(EPI) of a heavily-doped ground plane, and those are analyzed using TCAD(Technology Computer Aided Design) for scaling and simulation. The scaling has used a constant-voltage scaling method, and we have presented MOSFET´s characteristics such as I-V characteristic, impact ionization, electric field and recognized usefulness of TCAD, providing a physical basis for understanding how they relate to scaling.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.3
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• pp.187-194
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• 2020

In this study, computational analyses are carried out to investigate the interference flows and the aerodynamic characteristics of a hit-to-kill intercepter due to lateral jets at medium altitude. In addition, the analyses are performed for air and multi-species gas used in the side jet. The results indicate that the position of the barrel shock are shifted upstream and the structure of the shock wave are changed for the multi-species jet when compared to the air jet. As a result, the high pressure region with multi-species jet moves forward and the pitching moment is higher under the same flow condition. Moreover, the inclusion of high temperature effects makes drastic changes in pressure distribution. The jet width is much bigger, and the jet diffuses over wider range in medium altitude than in low altitude, because of the low density of the freestream.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.1
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• pp.97-102
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• 2013

A prestudy on expendable turbine engine for high-speed vehicle was conducted. After two possible mission profiles were established to decide the engine requirements, design point analysis was performed with the values of design parameter which were obtained from similar class engines, references, etc. The results showed that specific net thrust and specific fuel consumption with turbine inlet temperature of 3,600 R are 2,599.4 ft/s and 1.483 lb/(lb*h) respectively at the flight condition of sea level, Mach 1.2. It was also found that major design parameters for determining maximum net thrust were turbine inlet temperature for low supersonic and transonic flight speed and compressor exit temperature for high supersonic flight speed from the results of performance analysis on the two possible mission profiles. In addition, simple turbojet engine with an axial compressor, a straight annular combustor, an one stage axial turbine and a fixed throat area converge-diverge exhaust nozzle was proposed as the configuration of simple low cost lightweight turbine engine.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.1
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• pp.55-61
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• 2020

Social infrastructure facilities that have been under construction since the country's high-growth period are undergoing rapid aging, and, thus, safety assessments of large structures such as bridge tunnels, which can be directly linked to large-scale casualties in the event of an accident, are necessary. It is difficult to construct economical and efficient wireless smart sensor networks that improve structural health monitoring (SHM) because the existing wire sensors have a short signal reach. However, low-power wide-area networks (LPWANs) are becoming popular within the Internet of Things, and enable economical and efficient SHM. In this study, the technology trends of a wireless measuring sensor based on LoRa LPWANs were investigated, and an installation and maintenance plan for this type of sensor is proposed.