• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.836_837
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• 2009

PC용 냉각장치의 일환으로 CPU의 외벽에 방열판을 달고 열전냉각모듈을 설치한 후 방열판을 냉각하기 위해서 펌프를 적용한 수냉식 냉각 시스템을 개발하고자 하였다. 먼저, 냉각 시 펌프의 부하를 설계하고 그 용량에 적절한 저소음, 고효율 BLDC 모터를 개발하고자, 상용화된 외국제품인 S사의 저효율 단상 BLDC 모터가 적용된 수냉식 펌프를 기준으로 하였다. S사의 단상 BLDC 모터에 대한 시뮬레이션과 테스트를 통해서 거의 비슷한 결과를 얻었으며, 이를 이용하여 단가가 다소 상승하더라도 효율과 성능을 향상시킬 수 있는 3상 BLDC 모터구조로 설계를 하였으며, 그 결과 효율이 거의 2배 향상되며 출력 또한 향상됨을 시뮬레이션으로 구현하였다.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.393-397
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• 2013

관내의 유량을 제어하는 볼 밸브(ball valve)는 개폐각도(opening degree)가 커짐에 따라 출구에서 유속이 증가하고 밸브(valve)의 입 출구 간 압력강하(pressure drop)가 증가한다. 출구에서의 압력이 작동유체의 포화증기압보다 낮아질 때 공동현상(cavitation)이 발생한다. 관내에서의 공동현상은 배관시스템의 진동 및 소음, 부식 등에 있어서 악영향을 미칠 수 있으므로 설계에 매우 중요한 요소이다. 버터플라이 밸브를 비롯한 다른 밸브에서는 공동현상감소에 대한 연구가 많이 이루어졌다. 이에 본 연구에서는 볼 밸브 내 유동 특성(characteristic of flow)과 볼 밸브의 입출구간 압력강하를 줄이는 연구를 수행하였다. 개폐 각도와 그에 따른 압력강하와의 관계를 Edison_전산열유체를 사용하여 분석하고 공동현상을 감소시킨 볼 밸브의 설계를 제시 하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.148-151
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• 2021

본 논문은 oneM2M을 활용하여 스마트시티의 일환으로 사회적 이슈가 되고 있는 미세먼지(PM10, PM2.5) 측정 플랫폼을 설계하였다. 미세먼지 측정 디바이스를 이동식 차량에 부착하여 미세먼지가 측정이 되고 있지 않은 사각지대까지 범위를 넓혀 측정하였다. 또한 미세먼지뿐만 아니라 일상생활과 연관된 온도, 습도, 대기압, 휘발성 유기화합물(VOC), 일산화탄소(CO), 아황산가스(SO₂), 이산화질소(NO₂), 소음을 센서의 응답 시간에 따라 최소 10초 간격으로 수집하였다. 수집된 정보들은 미세먼지 측정 디바이스 기준으로 반경 1km내 격자모양으로 지형 화면에 실시간으로 표시하고 모니터링함으로서 동작성을 확인하였다.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.1-15
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• 2009

Surface of exposed aggregate concrete pavements is consists of exposed coarse aggregate by removing upper 2$\sim$3mm mortar of concrete slab. Exposed aggregate concrete pavements have advantages of maintaining low-noise and adequate skid-resistance level during the performance period. In order to provide the successful exposed concrete aggregate pavement, uniform distribution of the coarse aggregate on pavement surface through adequate the mix design and exposing method. The mix design in concrete pavement is generally designed on the basis of strength, but mix design of exposed aggregate pavement employed in this study includes the consideration of noise and skid resistance, as well as strength. Smaller of maximum coarse aggregate is known to be effective for reduce noise level. Optimum mix design and exposing method of fine-size exposed aggregate portland cement concrete pavement that can reducing the noise and maintain the adequate level of skid resistance are proposed in this study. To consider the variation of optimum exposing time due to the hardening speed of mortar by climatic condition, quantitative is also suggested measurement of hardening state.

• Journal of Korean Elementary Science Education
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• v.43 no.1
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• pp.136-147
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• 2024

It has recently be emphasized in science education that lessons that can develop "scientific participation and action" should be implemented to scientifically recognize various problems and respond to them as well as risks that occur in real life. This study aims to analyze the characteristics of scientific participation and action lessons as perceived by the preservice primary school teachers. To do that, the researchers collected and analyzed the lesson plans designed by the preservice teachers based on the achievement standard related to noise for grades 3-4 in 2022 revised science curriculum. Focusing on the stages of "problem recognition," "data collection and analysis," and "implementation and sharing," the results identity the four main characteristics as problem-solving activity, inquiry activity, investigative activity, and activity that encourages practical actions. The two or three features were found to be combinated in a lesson depending on its context. In some cases, only one feature was seen in a lesson. Based on the results, educational implications were discussed in terms of the teaching and learning methods and teacher education for implementing scientific participation and action.

• Science of Emotion and Sensibility
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• v.25 no.1
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• pp.3-20
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• 2022

Recently, prior to the commercialization of urban air mobility (UAM), the importance of R&D for air transportation-related industries in urban areas has significantly increased. To create a UAM environment, research is being conducted on personal air vehicles (PAVs). They are key means of air transportation, but research on the physical factors influencing their passengers is relatively insufficient. In particular, because the PAV is expected to be used as a living space for the passengers, research on the effects of the physical elements generated in the PAV on the human body is essential to design an interior space that supports the in-vehicle activities of the passengers. Therefore, the purpose of this study is to derive the constraint factors that affect the human body due to the air navigation characteristics of the PAV and to understand the impact of these constraint factors on the bodies of the passengers performing in-vehicle activities. The results of this study indicate that when the PAV was operated at less than 4,000 ft, which is the operating standard, the constraint factors were noise, vibration, and motion sickness caused by low-frequency motion. These constraint factors affect in-vehicle activity; thus, the in-vehicle activities that can be performed in a PAV were derived using autonomous cars, airplanes, and PAV concept cases. Furthermore, considering the impact of the constraint factors and their levels on the human body, recommended constraint factor criteria to support in-vehicle activities were established. To reduce the level of impact of the constraint factors on the human body and to support in-vehicle activity, the seat's shape and built-in functions of the seat (vibration reduction function, temperature control, LED lighting, etc.) and external noise reduction using a directional speaker for each individual seat were recommended. Moreover, it was suggested that interior materials for noise and vibration reduction should be used in the design of the interior space. The contributions of this study are the determination of the constraint factors affecting the in-vehicle PAV activity and the confirmation of the level of impact of the factors on the human body; in the future, these findings can be used as basic data for suitable PAV interior design.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.59-65
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• 2024

In this study, in order to improve the mechanical properties and durability of asphalt mixtures, a modifier (CSM, Cationized Silicate Modifier) was applied to asphalt to derive optimal mixing ratio conditions. Design of asphalt mixture using modified asphalt binder was conducted, and moisture resistance and dynamic stability were evaluated for optimal mixing conditions. The evaluation results showed that it exceeded the standards stipulated in the relevant guidelines, and as a result of conducting a water permeability test on the optimal mixing condition, it was confirmed that impermeable performance was secured. As a result of examining the noise reduction performance through field test, a noise reduction performance of about 10 dB was secured compared to before paving. It will be necessary to secure reliability through continuous noise generation evaluation in the future.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.648-655
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• 2005

The resilient mounts of a diesel engine installed onboard a ship should be designed for both static and dynamic loads. If possible, the resonance frequencies of the six rigid body modes of the installation and the flexible modes of the engine support structure should not lie within the engine operation range. In this paper a design criterion is proposed to evaluate an isolation system which involves the summation of dynamic forces transmitted through the resilient mounts and elastic potential energy index stored in the mounts. A case study is also presented in which a diesel engine generator, which had an elastic foundation and was mounted in a 5500 TEU container vessel, was studied both theoretically and experimentally. The theoretical analysis of the test model was performed by using a single mass 6 degree of freedom system. Actual measurements of mechanical vibration of the Engine and its foundation onboard were carried out, which showed the importance of including the flexibility of the engine support structure in the mode

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.4 s.109
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• pp.329-338
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• 2006

The resilient mounts of a diesel engine installed onboard a ship should be designed for both static and dynamic loads. If possible, the resonance frequencies of the six rigid body modes of the installation and the flexible modes of the engine support structure should not lie within the engine operation range. In this paper a design criterion is proposed to evaluate an isolation system which involves the summation of dynamic forces transmitted through the resilient mounts and elastic potential energy index stored in the mounts. A case study is also presented in which a diesel engine generator, which had an elastic foundation and was mounted in a 5500 TEU container vessel, was studied both theoretically and experimentally. The theoretical analysis of the test model was performed by using a single mass 6 degree of freedom system. Actual measurements of mechanical vibration of the engine and its foundation onboard were carried out, which showed the importance of including the flexibility of the engine support structure in the mode.

• Proceedings of the ESK Conference
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• 1997.10a
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• pp.451-455
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• 1997

본 연구의 목적은 국내 사무환경 실태조사를 통하여 사무환경 구성이나 사무환경 개선시 활용 할 수 있는 적용기준을 제안하고, 사무실 환경관리규정 설계시 활용하는데 있다. 실태조사는 관공 서 및 정부투자기관 사무실, 일반기업체 사무실을 대상으로 실시되었다. 조사 내용으로는 개인점유 면적, 가구 재질 등에 대한 일반적인 사무환경 조사와 소음환경, 온/습도환경, 조도환경 등과 같은 쾌적성의 요인이되는 환경을 측정하였다. 조사의 실시는 7월 20일 부터 9원 12일 사이에 이루어졌으며, 조사된 사무실은 총 39개 기관 45개사무실이다. 일반적으로 사무환경을 보면 1인 1PC 사용률은 77.3%, 1인 사무실 면적은 약 7.6M$^{2}$, 조명방식은 직접조명방식이 67.6%로 나타났으며, 별도의 회의 공간을 구획하여 사용하는 경우가 56.7%로 나타났다. 환경측정은 사무실을 출입구, 중앙, 안쪽(또는 창가) 등 3개 위치를 선정하여 바닥으로 부터 85cm 떨어진 지점에서 각각 3회씩 측정하였다. 조도의 경우 등과 등 사이의 평균 조도를 보면 출입구는 400.11x, 중앙은 481.91x, 안쪽은 629.61x로 나타났으며 등밑에서는 각각 435.81x,518.11x, 666.31x로 나타나 일반 사무실에서의 작업수준을 만족하고 있는 것으로 나타났다. 온도와 습도환경을 보면 측정지점별 각각 평균 27 .deg. C 54.5%, 26 .deg. 55.4%, 26.3 .deg. C 55.4%, 26.3 .deg. C 56.2%로 나타났으며, 소음환경은 측정위치별 각각 52.9db, 54.1db, 53.7db로 나타났다.