• 상하수도학회지
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• 제10권1호
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• pp.78-84
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• 1996

The presence of ammonia, usually in the form of ammonium ion ($NH_4{^+}$), can enhance bacterial growth m the distribution system and make the production of drinking water more costly if ammonium must be removed to ensure good disinfection. Removal of ammonia by biological oxidation could be economical which prevents excess chlorine dosage In this research, effects of hydraulic retention time (HRT) and media type on the ammonia removal efficiencies of submerged biofilm reactor were investigated. The biofilm reactors combined the characteristics of high biological solids capture efficiency and good hydraulic control. The results indicate that biofilms can remove over 77 percent of the ammonia with HRT of longer than 2 hr even at low temperature ranging from 14.6 to $16.6^{\circ}C$. The HRT has a significant effect on nitrification. The overall nitrification and efficiency of ammonia removal increase with increasing HRT. It has also been observed that when the fibrous media was used, the ammonia removal, nitrification rate and endurance to shock improved.

• 한국자동차공학회논문집
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• 제7권5호
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• pp.89-95
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• 1999

In this study, the corrosion resistance of the aluminum casting commercial materials used in the automotive engine parts with respect to the anti-freeze coolant environment has been tested by the potentio dynamic method. especially, the effect of borax additive in engine coolant on the corrosion resistance of the aluminum casting materials has been evaluated. It was found that the borax in commercial engine coolant, used to prevent the corrosion in cast iron engine, causes a pit corrosion of aluminum casting materials at high temperature. During the engine endurance test with the coolant containing borax, the aluminum cylinder head was failed by the pitting corrosion near the exhaust port. Conclusively, it was suggested that the use of borax in the anti-freeze coolant be restricted for the automotive with aluminum cylinder head.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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• pp.37-40
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• 2005

Light reflectance and arc resistance of PTFE composites were investigated. PTFE composites have been used widely as a material for circuit breaker nozzle. Arc energy is transported to the nozzle material by radiation. It is needed to add some fillers to PTFE to avoid energy penetration into the nozzle material. In this paper, some fillers that have endurance in the high temperature arc environment were added into PTFE. The light reflectance and arc resistance of PTFE composites according to the kinds and content of fillers were investigated.

• 항공우주기술
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• 제1권2호
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• pp.179-185
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• 2002

본 연구는 장기체공성 향상을 위한 개량형 무인기의 구조설계에 관한 방법 및 절차를 소개한 것이다. 상온 경화용 복합재료를 날개 전체에 적용하였다. 운반 및 보관의 용이성을 고려하여 날개 구조물을 3개로 분리하였고, 구조물의 경량화 및 강성의 증가를 위하여 샌드위치 구조물을 스킨 전영역에 적용하였고, 제한하중 4g에 해당되는 하중조건에서 구조강도시험을 수행하여 구조설계와 제작성을 점검하였다.

• 조명전기설비학회논문지
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• 제29권5호
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• pp.50-56
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• 2015

As rotor position is a reference of coordinate in vector control of PMSM, the information of exact rotor position is required. To measure the position of motors, hall-effect sensors, encoders, resolvers, etc. are used. Among these sensors, resolvers have good endurance in the variation of circumstance and can be used in a wide range of temperature, but resolvers are less exact than encoders. In addition, resolvers have a drawback that the output signal contains periodic error components. Thus, this paper proposes a compensation method for the unique position error in resolvers using Kalman filter to achieve high performance control of PMSM. The validity of the proposed scheme is demonstrated through simulation studies.

• 대한기계학회논문집A
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• 제40권11호
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• pp.935-941
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• 2016

고온기기의 부재로 널리 사용되는 인코넬 718을 사용하여 UNSM 표면처리법에 의한 처리효과를 기기의 사용조건을 고려한 실온, $300^{\circ}C$, $500^{\circ}C$ 및 $600^{\circ}C$ 의 세 가지 온도레벨하의 대기 중에서 고온피로 시험을 실시하여 각 시험편의 온도에 따른 피로특성을 연구하였다. 이때 고온회전굽힘피로시험(R=-1)은 할로겐(Halogen) 램프를 사용한 집광식인 가열방식을 선택한 새로운 피로시험기를 사용하였다. 인코넬 718의 고온피로강도는 상온에 비하여 감소하였다. 그러나 설계응력레벨에서는 상온의 내구한도와 유사한 경향을 나타내었다. UNSM 처리된 고온피로특성은 미처리재에 비하여 설계응력레벨에서 크게 향상되었다. 미처리재의 $300^{\circ}C$와 $500^{\circ}C$ 사이의 온도 영향은 거의 없었지만, $600^{\circ}C$에서는 높은 응력레벨에서 피로수명이 짧아졌지만, 낮은 설계응력레벨에서는 상온의 S-N선도보다 피로수명이 증가되는 경향을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.922-926
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• 2002

In this paper, in order to investigate the catalytic effect of the sludge exhausted from waterworks as heating temperature for NOx removal, we measure NO, $NO_2$ concentration as increasing temperature of sludge pellets and applying high voltage to sludge pellets in a quartz-glass reactor at the same time. NO initial concentration is 100ppm balanced with air gas in a mixing chamber. The gas flow is 5[l/min] and the heating temperature of sludge pellets in a quartz-glass reactor is adjusted from $200[^{\circ}C]$ $400[^{\circ}C]$ to investigate the effect of sludge pellets for removal NOx$(NO+NO_2)$ as increasing temperature. $BaTiO_3$ pellets is filled in a packed-bed reactor for corona discharge to measure how much NOx$(NO+NO_2)$ is removed after generating $NO_2$ from the packed-bed reactor. AC[60Hz] voltage is supplied to the reactor for discharge. In the result, $NO_2$ concentration is decreased by sludge pellets without heating temperature for sludge pellets in case of sludge pellets done heat treatment, however NO concentration is almost the same to be compared NO initial concentration. As increasing heating temperature for sludge pellets, $NO_2$ adsorbed on the sludge surface done heat treatment is converted to NO by the thermal energy, so NO concentration is extremely increased by reduction decomposition of $NO_2$. Finally, We think the sludge is possible to use for reduction catalysts, however we need to study more about the possibility and endurance of sludge as catalysts for NOx removal.

• 한국수소및신에너지학회논문집
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• 제31권1호
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• pp.89-95
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• 2020

The main scope of this paper is to see if the conventional pump can be properly used for a specific fuel, Di-methyl Ether (DME) despite of its low lubricity and high reactivity in the experimental conditions. A wobble plate type fuel pump was connected to the common rail to verify that the pump could deliver the fuel at the required pressure and resultantly DME could be used as fuel without modifying the original pump. At each required pressure (30 Mpa, 35 Mpa, 40 Mpa, 45 Mpa, and 50 Mpa), the pump met the pressure required by the common rail. In addition, pump performance experiments tended to follow the usual performance curve while the flow rate decreased as the pressure increased. The maximum flow rate of the pump was 470 kg/h at 30 Mpa and all measurements were taken with keeping DME temperature below 60℃.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.28.2-28.2
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• 2011

Resistance random access memory (ReRAM) is a promising candidate for next-generation nonvolatile memory because of its advantageous qualities such as simple structure, superior scalability, fast switching speed, low-power operation, and nondestructive readout. We investigated the resistive switching behavior of tantalum oxide that has been widely used in dynamic random access memories (DRAM) in the present semiconductor industry. As a result, it possesses full compatibility with the entrenched complementary metal-oxide-semiconductor processes. According to previous studies, TiN is a good oxygen reservoir. The TiN top electrode possesses the specific properties to control and modulate oxygen ion reproductively, which results in excellent resistive switching characteristics. This study presents fully room temperature fabricated the TiN/$TaO_x$/Pt devices and their electrical properties for nonvolatile memory application. In addition, we investigated the TiN electrode dependence of the electrical properties in $TaO_x$ memory devices. The devices exhibited a low operation voltage of 0.6 V as well as good endurance up to $10^5$ cycles. Moreover, the benefits of high devise yield multilevel storage possibility make them promising in the next generation nonvolatile memory applications.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.373-373
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• 2014

Resistive-change random access memory (ReRAM) device is one of the promising candidates owing to its simple structure, high scalability potential and low power operation. Many resistive switching devices using transition metal oxides materials such as NiO, Al2O3, ZnO, HfO2, $TiO_2$, have attracting increased attention in recent years as the next-generation nonvolatile memory. Among various transition metal oxides materials, HfO2 has been adopted as the gate dielectric in advanced Si devices. For this reason, it is advantageous to develop an HfO2-based ReRAM devices to leverage its compatibility with Si. However, the annealing temperature of these high-k thin films for a suitable resistive memory switching is high, so there are several reports for low temperature process including microwave irradiation. In this paper, we demonstrate the bipolar resistive switching characteristics in the microwave irradiation annealing processed Ag/HfO2/Pt ReRAM device. Compared to the as-deposited Ag/HfO2/Pt device, highly improved uniformity of resistance values and operating voltage were obtained from the micro wave annealing processed HfO2 ReRAM device. In addition, a stable DC endurance (>100 cycles) and a high data retention (>104 sec) were achieved.