• Journal of Platform Technology
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• 제9권4호
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• pp.42-50
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• 2021

최근 고령화로 인한 농촌인구의 감소, 생산량 감소, 해외 농산물 유입 등 경쟁 심화문제를 해결하기 위해 스마트팜 도입의 필요성이 점점 커지고 있으며 이에 따라 교육에 대한 필요성이 증가하고 있다. 본 논문은 농장의 스마트팜 시스템을 축소하여 실제 환경에서도 사용이 가능하도록 안드로이드 기반 교육용 IoT 스마트팜 구현에 관한 연구이다. 교육용 IoT 스마트팜을 이용하여 안드로이드 기반 교육이 실제 환경에서 적용이 가능함을 확인하기 위해 블루투스, 와이파이, 서버/클라이언트 통신 방식을 사용하여 자동모드와 수동모드로 실험을 수행하였다. 자동모드는 모든 데이터를 수신하여 실시간으로 현재 상태를 확인할 수 있었으며, 수동모드는 수신된 센서데이터를 이용하여 실시간으로 명령을 전송하여 원격제어하였다. 실험 결과, 각 통신 방식의 특성을 파악할 수 있었고 안드로이드 앱을 이용한 스마트팜 원격 모니터링 및 원격 제어가 가능함을 확인하였으며, 안드로이드 기반 스마트팜 교육이 실제 환경에서 적용이 가능하리라 사료된다.

• 한국물환경학회지
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• 제20권1호
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• pp.42-47
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• 2004

This study was accomplished to develope an advanced wastewater treatment process using high MLSS in anoxic tank aimed to improve nutrient removal and to reduce wasting sludge. It was operated with 4 Modes with varing solid concentration and internal recycle ratios. Mode I, II, III was operated 1.0~1.5% MLSS concentration at anoxic tank with 50% sludge recycle rate, however, each internal recycle rate were 100%, 200%, 300% and Mode IV was operated 1.5~2.0% MLSS concentration at anoxic tank with 50% sludge recycle rate and 100% internal recycle rate. The COD removal efficiency didn't show any big difference from Mode I to IV. The average COD removal rate was over than 90%. The T-N removal rate was 73%, the highest rate in all mode. The 36% of SCOD is used for the denitrification and phosphorus release in the anoxic tank. Specific denitrification rate was 3.5mg $NO_3{^-}-N/g$ Mv/hr and denitrification time was 0.7hr. As MLSS concentration is higher in anoxic tank as denitrification time would be shorter. The T-P removal rate was average 70%. The phosphorus release accomplished from the anoxic tank because the anaerobic condition was prevalent in the anoxic due to the prompt completion of denitrification. Sludge production was 0.28 kgVSS/kg $BOD_{removed}$ under the 1.5% MLSS and 17 day SRT. It is prominent result which has 40% sludge reduce comparing with traditional activate sludge system.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2011년도 추계학술논문집 1부
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• pp.14-17
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• 2011

본 논문에서는 현재 Jazz에서 사용되어지는 Modal 기법을 Wayne Shorter의 작품인 "El Gaucho"를 통해서 알아보았다. F음을 중심으로 3~4 Note의 단순한 선율과 Pentatonic적인 선율에 주로 사용된 본작품은 화성의 배열에 있어서 각 7개 Mode들의 특징적인 Chord들을 Modal Interchange 하고 있다.

• Journal of Microbiology and Biotechnology
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• 제15권2호
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• pp.362-367
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• 2005

On the basis of high osmotic tolerance and xylitol production, a novel yeast strain was screened from soils of rice farming. The isolated strain HY200 was systematically characterized by using general approaches of Biolog Microlog$^{TM}$ and 18S rRNA sequence analyses, and consequently was designated as Candida tropicalis HY200. Under formulated culture conditions, relatively high xylitol yield ($77\%$) and productivity (2.57 g/l$\codt$h) were obtained, in practice, when 200 g/l of xylose was supplemented. In the utilization of nitrogen, inorganic compounds could not serve as nitrogen sources. As a promising phenotype, HY200 steadily flocculated during and/or after growing in the formulated medium. The extent of flocculation was partly affected by nitrogen sources. However, regardless of the kinds of carbon source fed, the flocculent cells were always observed at the end of the exponential growth phase. These observations strongly suggest that the strain HY200 could effectively be used as a potential candidate for the production of xylitol from xylose, especially in repeated batch mode, because of its flocculation ability and tolerance to high substrate concentrations.

• 한국환경보건학회지
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• 제19권4호
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• pp.38-43
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• 1993

The characteristics of food wastewater treatment in an anaerobic packed bed reactor (APBR) with polyurethane as a packing material and sludge bed reactor (ASBR) was studied. The reactor of 9cm-ID, 150cm-height was fed in a continuous mode from bottom of reactor. For the purpose of constant temperature of reactor, water jacket was installed. The used packing materials was polyurethane sponge foam. Methane which was produced by decomposed organics collected at the top of the reactor for using as a fuel. The substrates used were synthetic, mixed and food wastewater. For the acclimatization of microorganisms, mixed wastewater was used. The major analyses were gas production, COD, pH and volatile acids. Based upon the completed works, the results are as follows: When food wastewater was fed the quantity of produced gas was less than that of synthetic wastewater, but food process saw higher methane content than synthetic process. As well as COD removal efficiency of food process reached at about 85%. In aspect of effluent volatile acid, food process showed low concentration of below 500 mg/l, therefore anaerobic reaction stabled. Conclusively food wastewater used can be digested by anaerobic treatment, especially anaerobic packed bed reactor showed 82% of COD removal, 75% of methane content, 10 l of gas production, and anaerobic sludge bed reactor did 79% of COD removal, 75% of methane content, 81 of gas production at 4 kgCOD/m$^3$day, 36$\circ$C.

• Journal of Welding and Joining
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• 제32권6호
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• pp.22-28
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• 2014

Most publications on friction stir welding describe phenomena or results with given process parameters like feed rate, rotation speed, angle and depth of penetration. But without a complete documentation of tool design, the results under the same process parameters are completely different. For this purpose, the Institute of Cutting and Joining Manufacturing Processes (tff), University of Kassel investigated the influence of tool roughness on the friction stir welding process. Therefore a defined surface finish was produced by turning and die sinking. As basis of comparison the constant parameters were rotation speed, feed rate, tilt angle and a heel plunge depth. Sound butt-welds were produced in aluminium alloy 6082 (AlMgSi1) with 1.5 mm sheet thickness with a turned reference tool with a surface of $Ra=0.575{\mu}m$ in position controlled mode. The surfaces are manufactured from a very fine to a very rough structure, classified by the VDI-classes with differences in the arithmetical mean roughness. It can be demonstrated with the help of temperature measures, that less heat is generated at the surfaces of the shoulder and the pin by the higher roughness due to lower active friction contact surface. This can also be seen in the resulting wormhole defects.

• Journal of Microbiology and Biotechnology
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• 제4권2호
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• pp.146-150
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• 1994

Production of poly-$\beta$-hydroxybutyrate (PHB) in fed-batch fermentation was studied. Utilization of carbon for PHB biosynthesis was investigated by using feeding solutions with different ratios of carbon to nitrogen (C/N). It was observed that at a high C/N ratio carbon source was more preferably utilized for PHB accumulation while its consumption for cellular metabolism appeared to be more favored at a low C/N value. A high cell concentration (184 g/l) was achieved when ammonium hydroxide solution was fed to control the pH, which was also utilized as the sole nitrogen source. For the mass production of PHB, two-stage fed-batch operations were carried out where PHB accumulation was observed to be stimulated by switching the ammonium feeding mode to the nitrogen limiting condition. A large amount of PHB (108 g/l) was obtained with cellular content of 80% within 50 hrs of operation.

• 신재생에너지
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• 제9권2호
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• pp.5-14
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• 2013

The efficiency of microwave-assisted acid hydrolysis of seaweeds for the production of ethanol was investigated and its effect on hydrolysis into reducing sugar and fermentation into ethanol evaluated as compared with those by conventional heating. A brown seaweed, Laminaria japonica (10-100g/L) was hydrolysed under dilute acidic condition (0.5N $H_2SO_4$, $100^{\circ}C$) with two sorts of heating: microwave irradiation for ${\leq}10min$ and conventional heating for 10-60min. Microwave-assisted hydrolysis was shown to be more efficient. A similar range of reducing sugar and ethanol yields as with the conventional autoclave heating procedure(${\geq}30min$) was observed, but it was obvious that production of ethanol from microwave-assisted hydrolysis had a 3 times faster reaction rate leading to very short production times, lower energy consumption/loss than from the conventional heating mode, and higher biomass loading without significant reducing ethanol yield, thus microwave-assisted acid hydrolysis is a potential alternative method for more effective hydrolysis of Laminaria japonica.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.287-290
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• 2000

회분배양에서 교반속도와 통기량에 대한 영향을 살펴본 결과 400 rpm과 1.0 vvm의 조건에서 균체량은 25.1 g/L, 다당체는 2.5 g/L로 가장 높게 생성되었다. 회분배양을 기초로 균체량과 다당체 생성을 높이기 위해 glucose를 대수기에 공급한 결과 배양 6일째 균체량은 29,2 g/L, 다당체 생성은 3.3 g/L로 회분배양보다 우수한 결과를 보였다.

• 한국가스학회지
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• 제9권4호
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• pp.44-49
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• 2005

본 연구에서는 Steam Reforming수소 제조설비에 대한 안전성 평가를 수행하여 설비의 위험성을 체계적으로 검토하였다 안전성 평가 방법으로는 정성적 안전성 기법인 Hazard & Operability Analysis와 Failure Mode & Effect Analysis를 사용하였다. HAZOP을 통하여 수소 제조설비의 flow, pressure, temperature 등의 주요 parameter들에 대하여 의미 있는 guide word를 적용하여 비정상 상태(deviation)를 만들어 단계별로 공정상의 인간 실수나 잘못된 운전 등의 잠재 위험을 분석하였다. FMEA를 이용하여 설비 내 장치의 파손 및 기능 실패 등 주로 부품의 불량이나 고장 등에 대한 분석을 하여 그에 따른 영향 및 대처방안을 제시하였고, RPN값 계산을 통하여 상대적 위험순위를 결정하여 보았다.