• 한국소음진동공학회논문집
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• 제23권1호
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• pp.34-40
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• 2013

The 1st assessment(performance test) was applied to assure the floor impact sound performance for developing the dry double-floor with the change of rubber hardness of the upper panel's support and the ceiling structure of the sub-floor. Depends on the change of the rubber hardness in sub-structure, the heavy-weight sound impact value is improved up to 3 dB, and the light-weight sound impact value is moved up to 21 dB, comparing with the bare-slab. Also, the improved value for the floor impact sound conjugating with the sub-floor's ceiling was 5 dB. Based on this result, the 2nd assessment(performance test) was made the state that the rubber hardness of the sub-floor support was ranged between 50 and 70 for considering the stability of walking patients. In addition to this process, the assessment was carried out with a variety of ceiling structure applied to the dry double-floor structure with the air flow system on the sub-floor's ceiling. The result for the 2nd assessment proved that TYPEII-3 had the better sound reduction performance in the heavy-weight impact sound test than other types, and also for the light-weight impact sound TYPEII-3 had the 29 dB sound reduction performance overall. Henceforth, based on the result the research for the sound reduction performance from the floor impact sound shall be ongoing process as well as the development of a double-dry floor and a sound reduction ceiling to suitable on the field.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.164-169
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• 2001

There is a chilled ceiling panel which carries out the air conditioning by radiation and convection between the room and cold ceiling panel surface. In order to verify heat transfer characteristics between them in cooling system with radiant chilled ceiling panel, analytical and experimental studies were performed for various design and operating parameters such as tube space and diameter, inlet water temperature, mass flow rate, cooling load, and so on. In this study, we found that the tube space and inlet water temperature were more important elements than the tube diameter and water flow rate for the performance of radiant chilled ceiling panel. The cooling capacity of the radiant chilled ceiling panel had the maximum value of $65W/m^{2}$ because the highest cooling capacity was limited by the condensation on the panel surface. The results of comparison between numerical analysis and experiment showed a resonable agreement qualitatively, especially for low cooling capacity.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.280-285
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• 2012

The 1st assessment (performance test) was applied to assure the floor impact sound performance for developing the dry double- floor with the change of rubber hardness of the upper panel's support and the ceiling structure of the sub-floor. Depends on the change of the rubber hardness in substructure, the heavy-weight sound impact value is improved up to 3 dB, and the light-weight sound impact value is moved up to 21 dB, comparing with the bare-slab. Also, the improved value for the floor impact sound conjugating with the sub-floor's ceiling was 5dB. Based on this result, the 2nd assessment (performance test) was made the state that the rubber hardness of the sub-floor support was ranged between 50 and 70 for considering the stability of walking patients. In addition to this process, the assessment was carried out with a variety of ceiling structure applied to the dry doublefloor structure with the air flow system on the sub-floor's ceiling. The result for the 2nd assessment proved that TYPE-11 had the better sound reduction performance in the heavy-weight impact sound test than other types, and also for the light-weight impact sound TYPE-11 had the 29 dB sound reduction performance overall. Henceforth, based on the result the research for the sound reduction performance from the floor impact sound shall be ongoing process as well as the development of a double-dry floor and a sound reduction ceiling to suitable on the field.

• KIEAE Journal
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• 제2권1호
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• pp.41-48
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• 2002

This study aims to investigate and evaluate the room acoustic designs of a multi purpose gymnasiums which do not use adjustable treatments in order to change the acoustical characteristics. Considering the main uses of gymnasium and auditorium, experiments were carried out using both nondirectional speakers on the stage and loudspeaker installed on the ceiling. The result from the study are as follows; Measured RT under unoccupied condition was a little longer than the expected value, therefore, in the case of occupied condition RT would be close to the optimum value. However, parameters that evaluate intelligibility and speech transmission property appeared to be low and have large differences depending on the measuring points, therefore, more effective sound reflecting surfaces and sound reinforcement systems should be considered.

• 한국산업보건학회지
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• 제22권1호
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• pp.42-51
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• 2012

Objectives: To compare the exposure level of extremely low frequency (ELF) magnetic fields among semiconductor workers, shipyard welders and office workers. Methods: To measure the ELF magnetic field concentration, EMDEX LITE (Enertech, USA) were used and monitored for eight hours continuously. Five companies handling the electric and magnetic field (EMF) source were investigated, which the exposure groups were classified into three groups: semiconductor workers, welders, and office workers. Welder group was chosen as a high exposed group and office group as a low exposed group. Results: The arithmetic mean (${\pm}SD$) and geometric mean (GSD) of personal exposure level of semiconductor workers were 0.73 (${\pm}1.33$) ${\mu}T$, 0.43 (2.88) ${\mu}T$, respectively. The ceiling value ranged between 0.18 and 123.2 ${\mu}T$. Welders were exposed high with the arithmetic mean value of 3.46 (${\pm}\;13.46$) ${\mu}T$ and geometric mean value of 0.45 (4.70) ${\mu}T$, respectively, and ceiling value range of 75.5~129.6 ${\mu}T$. The exposure levels of office workers were low compared to other exposed groups; the arithmetic mean 0.05 (${\pm}0.13$) ${\mu}T$, geometric mean 0.03 (2.38) ${\mu}T$ and ceiling value range 0.37~3.35 ${\mu}T$. This study revealed statistically significant differences of the mean ELF magnetic field exposure doses among three groups (p < 0.01). Conclusions: The average ELF magnetic field exposure doses of semiconductor workers were much higher than those of office workers in control group, but were lower than those of welders in high exposure group.

• 토지주택연구
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• 제12권2호
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• pp.79-89
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• 2021

본 연구는 다른 창가 방향에 따라 소규모 개인 사무실의 바닥과 천장의 수평 일광 분포를 분석하였다. 시뮬레이션에는 블라인드를 추가하여 다양한 일광 조도를 분석하고 비교할 수 있는 세 가지 음영 조건을 설정했다. 일광 조도 시뮬레이션을 위한 소프트웨어는 Relux였다. 실험 결과 창가에서 1m 떨어진 곳에서 조도 값이 가장 높았고 거리가 가까울수록 조도 값이 높았다. 바닥과 천장에서는 조도 차이가 12월과 6월에 각각 가장 크고 작았다. 실내 조도 값은 블라인드가 없을 때 가장 높았고, 남향 조건에서는 조도의 45°와 수평 블라인드의 차이가 가장 컸다. 북쪽 조건에서는 45°와 무 블라인드가 실내 조도에 가장 적은 영향을 미치며, 조도가 더 고르게 분배되었다.

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.898-904
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• 2016

In this study, we have dealt with a design characteristic of outer-rotor type permanent magnet (PM) motor applied for Engine Cooling Fan (ECF). When we design a motor with structure like this type, it is required as a requisite to consider 3-Dimensional (3-D) effect by implementing a non-linear Finite Element Analysis (FEA) due to a yoke-ceiling, which is perpendicular to the axis of rotation. We have analyzed identical models under three different conditions. The analysis has been performed through a non-linear 2-Dimensional (2-D) and 3-D FEA. Finally, the results have been compared with Back Electro-Motive Force (BEMF) value of actual motor model. As a result, a yoke-ceiling function as an additional flux path and the operating point on B-H curve of rotor material is shifted to non-saturation region relatively. Accordingly, magnetic flux linkage can be increased and motor size can be decreased under same input condition to satisfy ECF specification, such as torque.

• 한국입자에어로졸학회지
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• 제17권2호
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• pp.29-36
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• 2021

In this study, the clean air delivery rate (CADR) of ceiling air circulator (CAA) was determined under indoor environmental simulation conditions. An air filter was used to provide air cleaning ability to the CAA. The CADR of filter adapted CAA was evaluated and compared with the value of commercial air purifier. The installation of mesh-shaped filter on the CAA showed particle reduction effect on the particles over 0.4 ㎛ in diameter, but the CADR was up to 0.25 m³/min. When the filter having 99.9% in collection efficiency was installed on the CAA, its CADR was 1.52 m³/min, while the CADR of commercial air purifier was 3.19 m³/min.

• 해양환경안전학회지
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• 제26권5호
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• pp.454-465
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• 2020

소형선박 기관실 내 화재 시 개구부 유동 및 온도에 대해 FDS(Fire Dynamics Simulator)를 이용하여 화재시뮬레이션을 수행하였다. 열방출률이 10 kW 급인 경유(Diesel) 화재를 대상으로 하였고, 천장 통풍통의 위치, 측면 개구부 유·무 및 크기에 대한 영향을 파악하였다. 측면 개구부의 유·무 및 크기는 연기 거동 뿐 아니라 개구부를 통한 질량 유량 및 온도에 지대한 영향을 미쳤다. 측면 개구부가 미설치되거나 크기가 작은 경우 연기층이 기관실 내 바닥까지 도달하였고, 측면 개구부의 크기가 증가함에 따라 개구부를 통한 질량 유량이 증가하고 온도는 감소하는 경향이 나타났다. 반면, 천장 통풍통의 위치가 연기 거동, 개구부를 통한 질량 유량 및 온도에 미치는 영향은 측면 개구부 크기에 비해 상대적으로 미미한 것으로 관찰되었다. 따라서 소형선박의 기관실 내 화재 시 안전성 향상을 위해서는 천장 통풍통 위치보다 측면 개구부의 크기가 더 중요한 설계 인자인 것으로 판단된다.

• 대한건축학회논문집:구조계
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• 제33권12호
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• pp.37-44
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• 2017

Due to structural characteristics, construction costs and duration of a modular system would be saved by minimizing the schedule on the job site. As such, it is crucial to develop a connection that can guarantee stiffness while allowing for simple assembling. Particularly, the mid- to high-rise construction of the modular system necessitates the securing of the structural stability and seismic performance of multi-unit frames and connections, and thus, the stiffness of unit-assembled structures needs to be re-evaluated and designed. However, evaluating a frame consisting of slender members and reinforcing materials is a complicated process. Therefore, the present study aims to examine the structural characteristics of a modular unit connection based a method for reinforcing connection brackets and hinges while minimizing the loss of the cross section. Toward this end, the study modeled the beam-to-column connection of a modular system with the proposed connection, and produced a specimen which was used to perform a cycling loading test. The study compared the initial stiffness, the attributes of the hysteretic behavior, and the maximum flexural moment, and observed whether the model acquired the seismic performance, compared to the flexural strength of the steel moment frame connection that is required by the Korean Building Code. The test results showed that the proposed connection produced a similar initial stiffness value to that of the theoretical equation, and its maximum strength exceeded the theoretical strength. Furthermore, the model with a larger ceiling bracket showed higher seismic performance, which was further increased by the reinforcement of the plate.