• 한국태양에너지학회 논문집
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• 제28권5호
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• pp.1-7
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• 2008

Flashed steam system is one of the important geothermal power production methods. In this paper, optimum operations and performances of single and double flash systems are presented. It is shown that double flash system can produce about 26.5% more power than single flash system. Temperature of geothermal water($T_R$) is the most important parameter in the geothermal system. Optimum single and double flash temperatures and net power produced with these optimum conditions are expressed as a function of $T_R$ in this study. Thus net power output from geothermal resources can be estimated with the results of this work. Condenser Temperature($T_{con}$) is also important and the net power production can be shown as a function of ($T_R-T_{con}$. Volume flow rate per unit power is also to be considered as the condenser temperature decreases.

• 한국인터넷방송통신학회논문지
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• 제15권5호
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• pp.193-199
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• 2015

요즈음, 온도 및 습도, 조도 센서를 이용하여서, 식물 재배 환경 정보를 자동으로 수집하고 생장환경을 관리하는 지능형 온실 시스템이 많이 연구되고 있다. 본 논문에서는 조도, 온도 및 습도를 예측해서 인터넷 기반에서, 식물 재배의 최적 환경 조건을 추론하는 모의실험을 하였다. IOT 환경에서, 식물 재배 조건을 온도, 습도, 조도를 아두이노 센서에 실시간으로 온실 관리자에게 전송해서, 식물 재배에 필요한 최적의 온도, 습도 조건 값보다 크거나 적으면 자동으로 SMS 경고 문자를 실시간으로 전송해 주기 때문에, 급격한 기후 변화 (눈,비, 폭염)조건일 경우라도 최적의 화초 재배조건을 관리 할 수 있다. 본 논문에서는 퍼지논리와 WEKA TOOL을 이용하여서, 같은 온대 식물이라도, 그 지역에 필요한 최적의 온도, 습도, 조도(일사량) 수치를 산출하는 모의실험을 하였다.

• 한국정밀공학회지
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• 제22권11호
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• pp.45-50
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• 2005

In this study, the casting/forging process was applied in manufacturing a low control arm, in order to prove that application of casting/forging process to Al6061 is likely to get the effect of light weight compared with existing steel products and to reduce the cost of materials. Firstly, In order to set up the optimum casting condition of the forging material, Al6061, casting experiments were carried out by controlling pouring temperature of the aluminum for casting, mold temperature, and pouring time. $700^{\circ}C$ pouring temperature, $300^{\circ}C$ mold temperature and 10-second pouring time were taken into account as the optimum casting conditions. With respect to a hot forging test, it is practiced on the basis of a temperature of materials, strain rate, and reduction rate so as to observe each microstructure and examine strain-stress curve simultaneously; examine tensile test and hardness test; eventually set up the optimum hot forging condition. A hot forging test, tensile test, hardness experiment, and microstructure observation were carried out on condition of $70\%$ reduction rate, $500^{\circ}C$ temperature of materials, and 1 strain rate. As a result of those experiments, 330MPa tensile strength, $16.4\%$ elongation, and 122.8Hv hardness were recorded. In oder to get a sound preform which has no unfitting cavity and less flash, two preforms were proposed on the basis of volume rate of the final product; the optimum volume rate of preform for the low control arm was $115\%$. In conclusion, it is confirmed that using the forging material rather than casting materials in casting/forging process is likely to get more superior mechanical properties. Compared with Al6061, performed by means of general forging, moreover, cast/forged Al6061 can not only stimulate productivity by reducing production processes, but cut down the cost of materials by reusing forging scraps.

• 한국수산과학회지
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• 제43권2호
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• pp.139-145
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• 2010

This study investigated the optimum salinity and temperature conditions for mass culture of the brackish water flea, Diaphanosoma celebensis. Community and individual cultures of flea were maintained in 1 L beakers and 3 mL vessels (of a 12-well culture plate), respectively, and fed green algae, Tetraselmis suecica. In salinity experiments ranging from 5 to 34 psu, continuous growth of flea populations was found up to 34 psu. However, the specific growth rate and life span of females showed decreasing tendencies with the increase of salinity. The highest maximum density and offspring number were 33.6 individuals (ind.)/mL and 55.3 ind. at 10 psu, respectively. In the temperature experiments ranging from 20 to $40^{\circ}C$, population growth of D. celebensis increased continuously until $35^{\circ}C$ and then decreased over $40^{\circ}C$. The specific growth rate was significantly higher at 25 and $30^{\circ}C$ than at 20 and $40^{\circ}C$. Female life span tended to decrease with temperature increase. The highest maximum density and offspring number were 52.3 ind./mL and 46.0 ind. at $30^{\circ}C$, respectively. These results suggest that the optimum salinity and temperature for mass culture of D. celebensis may be 10 psu and $30^{\circ}C$, respectively.

• 대한기계학회논문집A
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• 제32권11호
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• pp.957-962
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• 2008

Crack-healing behavior of $Si_3N_4$ composite ceramics has been studied as functions of heat-treatment temperature and amount of additive $SiO_2$ colloidal. Results showed that optimum amount of additive $SiO_2$ colloidal and coating of $SiO_2$ colloidal on crack could significantly increase the bending strength. The heat-treatment temperature has a profound influence on the extent of crack healing and the degree of strength recovery. The optimum heat-treatment temperature depends on the amount of additive $SiO_2$ colloidal. Crack healing strength was far the better cracked specimen with $SiO_2$ colloidal coating on crack surface. After heat treatment at the temperature 1,273 K in air, the crack morphology almost entirely disappeared by scanning prob microscope. At optimum healing temperature 1,273 K, the bending strength with additive $SiO_2$ colloidal 0.0 wt.% without $SiO_2$ colloidal coating recovered to the value of the smooth specimens at room temperature for the investigated crack sizes $100\;{\mu}m$. But that with $SiO_2$ colloidal coating increase up to 140 %. The amount of optimum additive $SiO_2$ colloidal was 1.3 wt.% and crack healed bending strength with $SiO_2$ colloidal coating increase up to 160 % to smooth specimen of additive $SiO_2$ colloidal 0.0 wt.%. Crack closure and rebonding of the crack due to oxidation of cracked surfaces were suggested as a dominant healing mechanism operating in $Si_3N_4$ composite ceramics.

• 한국분말재료학회지
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• 제4권3호
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• pp.170-178
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• 1997

An investigation was performed to apply the M3/2 grade high speed steel for metal injection molding using both prealloyed and elementally blended powders. The injected samples were subjected to a debinding step in $H_2/N_2$ gas atmosphere at a ratio that affected the carbon content of the material. The carbon content ranged from 1.4wt.% to 1.43wt%. with increasing $H_2$ content up to 80% $H_2$ in $H_2/N_2$ atmosphere for the prealloyed powders. The carbon contents of the elementally blended powders exhibited 1.44wt.% and 1.62wt.% at 10% $H_2/N_2$ and 20% $H_2/N_2$ gas, respectively. This level decreased to 0.17wt.% upon increasing the $H_2$ content. The sintered density of both powders increased rapidly as the temperature reached the liquid phase forming temperature. After forming the liquid phase, the density rapidly increased to the optimum sintering temperature for the prealloyed powders, whereas the density of mixed elemental powders goes up slowly to the optimum sintering temperature. The optimum sintering temperature and density are 126$0^{\circ}C$ and 97.3% for the prealloyed powders and 128$0^{\circ}C$ and 96.9% for the elementally blended powders, respectively. The microstructure of the specimen at the optimum sintering temperature consisted of fine grains with primary carbides of MC and $M_6C$ type for the prealloyed powders. The elementally blended powders exhibited coarse grains with eutectic carbides of MC, $M_2C$ and $M_6C$ type.

• 공업화학
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• 제22권6호
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• pp.658-663
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• 2011

SNCR-SCR hybrid system은 SNCR에서 NOx를 제거한 뒤, SCR로 NOx를 추가 제거하는 시스템으로 NOx 제거 효율을 향상시키는 경제적인 시스템이다. 본 연구에서는 SNCR-SCR hybrid system에서 운전 변수가 질소산화물 저감 효율에 미치는 영향을 고찰하였다. SNCR을 optimum temperature ($900{\sim}950^{\circ}C$)보다 낮은 온도에서 운전할 경우, 추가적인 암모니아 주입 없이도 $NH_3$ slip을 이용한 NO의 추가적인 제거의 효과가 있었으나 $NH_3$ slip이 높은 것으로 나타났다. 그러나 그 이상의 온도에서는 고온에 의한 암모니아의 분해로 SCR에 의한 추가 제거의 효과를 얻지 못했다. 따라서 SNCR 공정을 optimum temperature에서 운전하는 것이 NO 제거 효율과 $NH_3$ slip 농도를 고찰하였을 때 가장 적절하였으며, $SR_{RES}$가 적정 수준으로 유지되도록 NSR을 조절하는 것이 중요한 운전 변수인 것으로 나타났다.

• 수산해양기술연구
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• 제51권1호
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• pp.94-101
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• 2015

The heat treatment machine based on immersion was developed to reduce temperature difference during netting process and appraised it performance compared current heat treatment machine using high pressure. It was also reviewed the optimum heat treatment procedures for PBSAT monofilament net in accordance with the immersion time and temperature. The procedure was based on physical measurement such as breaking load, elongation and angle of the mesh for PBSAT monofilament. The water temperature gap of the treatment machine based on immersion was less than $1^{\circ}C$. and the energy consumption was also increased in high temperature condition. It was identified that the optimum temperature was $75^{\circ}C$ and its optimum processing time was between 15 minutes and 20 minutes to get qualified physical properties.

• 한국전기전자재료학회논문지
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• 제14권1호
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• pp.34-42
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• 2001

The influences of substrate temperature were studied when fabricating KLN thin film on amorphous substrate using an rf-magnetron sputtering method. Investigating the vaporization temperature of the each element, the excess ratio of target and the optimum deposition conditions were effectively selected when thin filmizing a material which have elements with large difference fo vaporization temperature. In order to compensate K and Li which have lower vaporization temperatures than Nb, KLN target of composition excess with K of 60% and Li of 30% was used. KLN thin film fabricated on Corning 1737 glass substrate had single KLN phase above 58$0^{\circ}C$ of substrate temperature and crystallized to c-axis direction. The optimum conditions were rf power of 100W, process pressure of 150mTorr, and substrate temperature of $600^{\circ}C$.

• 센서학회지
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• 제14권3호
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• pp.180-185
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• 2005

In this study, a plastic fiber-optic temperature sensor is fabricated using TSCM(thermo sensitive clouding material) which changes its light transmittance with temperature and the characteristics of this sensor are evaluated. The fabricated fiber optic temperature sensor is the reflector type using a Y-coupler. The optimum light source and reflector are decided by measuring the amount of reflected light through TSCM. Also, the optimum distance from the end of sensor to the surface of reflector is determined. Then the relationship between the amount of measured reflected light and the temperature of TSCM is found.