• 한국환경농학회지
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• 제27권4호
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• pp.321-327
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• 2008

본 연구는 간척지 토양 중 미사질양토에 대하여 입단형성을 위해 가해진 토양개량제가 토양 중 양이온 함량변화에 미치는 영향을 분석하기 위하여 토양개량제로 이수석고 1550 (G1), 3100 (G2), 6200 (G3) kg/10 a, 팽화왕겨 1000 (H1), 2000 (H2), 3000 (H3) kg/10 a, 팽화왕겨 1500 kg/10 a에 zeolite 200 (HZ1), 400 (HZ2), 800 (HZ3) kg/10 a가 되도록 처리량을 달리하여 3년간 연용시용하고, 버뮤다그래스를 재배한 토양을 60, 90, 120일 경과 후 채취하여 토양개량제 연용이 토양 중 양이온 함량변화에 미치는 결과를 보고한다. 이수석고의 처리는 토양 중 K, Na, Mg의 함량을 현저히 감소시키는 것으로 나타났다. K 함량은 연용 토양개량제의 종류 및 처리수준과 관계없이 년도별 감소현상이 뚜렷하여서 2004 > 2005 > 2006 순으로 낮아지는 경향을 나타내었다. 또한 각 년도별 토양 중 K 함량은 안정적 변화를 보이면서 이수석고 < 팽화왕겨 < 팽화왕겨+zeolite 순으로 토양 중 K 함량이 높았다. Na 함량은 이수석고 < 팽화왕겨 < 팽화왕겨+zeolite의 순으로 연용 토양개량제의 종류 및 처리수준과 관계없이 각 년도에서에서 높게 나타났다. 특히 팽화왕겨 및 팽화왕겨+zeolite의 각각 처리는 이수석고 처리구와는 달리 대조구의 Na 함량 보다 높아지고 있는 현상이 계화도 세사양토의 결과와 비교가 되었다. Mg 함량은 년도별 변화는 이 수석고 < 팽화왕겨+zeolite < 팽화왕겨 순으로 높아지고, 연용기간이 길수록 높아지는 경향이었다. 이수석고 연용처리는 세사양토에서 보여준 결과와 유사하게 처리수준이 높을수록 토양 중 Ca이 높아지는 결과가 되었으며, 년도별 변화도 2004 < 2005 < 2006년의 순으로 연용년수에 따라 높아졌다.

• 한국조명전기설비학회지:조명전기설비
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• 제9권4호
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• pp.62-70
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• 1995

Brushless DC Motor (BDCM) is widely used in the industry such as a variable speed motor in a compressor for room air conditioners, because the motor can be easily controlled and operated over a wide speed range. The system to drive BDCM needs encoder that senses rotor position. Gut in a certain application, the position sensor has to be avoided. In the paper, various position sensorless drive systems for BDCM are investigated and critically evaluated, so that the effective method of sensorless control can be selected. Out of these methods, the freewheeling diode current sensing has many advantages. For example, the simple starting procedure makes it possible to perform sensorless control even in low speed. So the hardware design for this method has been carried out and the system has been implemented using DSP. The experimental results verified that the freewheeling diode current sensing approach has advantages in starting procedure and low speed sensing.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.94-99
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• 2011

EMU(Electric Multiple Unit) of Seoul Metro are equipped with air conditioning and six line flow fans for air circulation. In summer, the air conditioning and line flow fans usually work at the same time. Recently, high oil price leads more people to use public transportation, which in turn makes them feel hotter inside the rolling stocks and complain about air conditioning state. In order to improve indoor air quality in summer, it is inevitable to increase the cooling capacity of air conditioners, which costs a lot of money. Thus, we need to raise cooling efficiency by rearranging existing devices effectively. In this study, we found a better way to improve refreshment inside the trains by changing the operation method of line flow fans and door opening systems. The results will help improve the cooling efficiency of EMU in summer. Also, more precise experiments and analyses of our data can lead to various methods to increase energy efficiency.

• 산업기술연구
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• 제36권
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• pp.83-88
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• 2016

In this study, a series of experiment was carried to improve dewaterability of the sludge produced in a treatment plant, located in Hongcheon, Gangwondo, which has been treating municipal wastewater and livestock wastewater. Optimum sludge mixing ratio and the amount of sludge conditioner were determined. As sludge conditioners, alum and ferric salt were selected and tested. For the measurement of sludge dewaterability, capillary suction time(CST) and the specific resistance were measured, The specific resistance was detemined by running a series of Buchner Funnel Test. Mixing the two sludges at a 50:50 ratio with the addition of 20 mL alum gave the best results in terms of dewaterability. The moisture content decreased by 2% at this condition.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.95-96
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• 2015

This paper aims to identify patterns in users' requests for facility management (FM) services in higher education facilities. We analyzed data collected from 309 service request forms, made available via a department office and an enterprise resource planning system, at a private university in Seoul between May 2009 and February 2015. We found that the number of user requests were the highest in September and October. Requests for electronic and communication (E/C) services outnumbered those for architectural services and mechanical and plumbing (M/P) services. Repair requests for doors and windows were the most common under architectural services; repairs for air-conditioners and radiators were the most commonly under M/P services; and installation of electrical outlets, telephone wires, and internet services were the most sought-after E/C services. Maintenance requests were received every three months, while repair requests were received every six or seven months.

• Design & Manufacturing
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• 제8권1호
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• pp.5-9
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• 2014

This study is about 3D design for parts supporting copper pipes of wall-mounted air-conditioners manufactured by company "D" in Japan. Domestic press die manufacturers are obsessed with 2D die design and are afraid of taking risk with developing 3D die design and die manufacture. This hinders paradigm shift. In this study, the strip layout, which was already completed in the previous study, is altered by adding restriking. Based on the modified strip layout, the 3D die design is done in 15 processes.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.687-691
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• 2001

With today's global environmental and energy problems, high expectations exist for solar power generation to reduce carbon dioxide generated by the consumption of fossil fuels. On the other hand, power consumption in residential homes is increasing every year. Among the many household appliances, the power demand for air conditioners increases dramatically during the summer, particularly in the afternoons. As this pattern closely matches the output pattern of solar cells, it should be possible to combine a photovoltaic array with an air conditioner to decrease the energy consumption within the home. We have developed a residential solar-powered air conditioner that operates through a combination of photovoltaic array and commercial power. In this paper, the configuration and specification of the residential solar-powered system are described to a novel high efficiency inverter using a ZVCS boost converter. And the performance evaluations of the solar-powered air conditioner are examined by the analysis of a new tracking controller with a maximum power $P_{max}$ detection of solar cell.

• 설비공학논문집
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• 제16권6호
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• pp.566-573
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• 2004

Comparison of the cooling performance is provided between the desiccant cool-ing systems incorporating a direct evaporative cooler and a regenerative evaporative cooler, respectively. Cycle simulation is conducted, and the cooling capacity and COP are evaluated at various temperature and humidity conditions. The COP of the system with a regenerative evaporative cooler and the regeneration temperature of 6$0^{\circ}C$ is evaluated 0.65 at the outdoor air condition of 35$^{\circ}C$ and 40% RH. This value is found about 3.4 times larger than that of the system with a direct evaporative cooler. Furthermore, incorporating a regenerative evaporative cooler eliminates the need for deep dehumidification in a desiccant dehumidifier that is necessary to achieve low air temperature in the system with a direct evaporative cooler. Subsequently, the regenerative evaporative cooler enables the use of low temperature heat source to regenerate the dehumidifier permitting the desiccant cooling system more beneficial compared with other thermal driven air conditioners.

• 대한치과보철학회지
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• 제37권3호
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• pp.293-300
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• 1999

The purpose of this study was to evaluate the in vitro antifungal effect of several kinds of denture lining materials containing nystatin and silver-zeolite on Candida albicans. Three commercially available tissue conditioners (Soft-Liner, Coe-Comfort, Coe-Soft) and two direct denture relining materials (Tokuso Rebase, Durabase) were selected. In terms of the zone of inhibition and some basic physical properties, I could find the following results ; 1. Nystatin or silver-zeolite included in those relining materials had definite antifungal activities against the Candida albicans. 2. As times went on, both of the antifungal agents's activities decreased gradually. 3. Antifungal agents did not affect the relining materials' basic physical properties. 4 Direct chairside relining materials showed unfavorable dark discoloration with response to silver-zeolite.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.154-157
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• 2005

Generally, noise from a indoor air conditioner has been measured by overall sound pressure level, dB. Customers evaluation, however, of the noise from an air conditioners should not be depend on the only overall level but also the sensory feeling. Moreover, in this sensory evaluation, irregular, time-varying and uneven sounds which are difficult to describe itself by overall level are more affectable. Unfortunately however the formal evaluation method for this kinds of noise is not determined yet. In this research, the evaluation method for tonal noise, which is one of the unmeasurable sounds by overall level, is proposed to evaluate its acceptability based on the consumer's sense of hearing. To consider the consumer's sense, several times of Jury evaluation are carried out. The proposed approach could be applied to the other sound, which acoustical characteristics are similar to the tonal noise .