• Structural Engineering and Mechanics
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• 제82권3호
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• pp.283-294
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• 2022

An inerter is a passive mechanical element whose inertance can be thousands of times its own physical mass. This paper discusses the application of an inerter-based passive control system, termed rotational inertial double-tuned mass damper (RIDTMD), to mitigate human-induced floor vibrations. First, the acceleration frequency response function of the floor with an RIDTMD is first derived. It is then employed to determine the optimal design parameters of the RIDTMD using the extended fixed-points technique. Based on a theoretical analysis, design-oriented empirical functions are proposed for the RIDTMD optimal parameters, whose performance for floor vibration control is evaluated by numerical examples, in which three typical human-induced load types are considered: walking, jumping, and bouncing. The results indicate that the applicability and effectiveness of the RIDTMD for human-induced floor vibration control are robust for various load types, load frequencies, and floor natural frequencies. For the same mass ratio, the RIDTMD is better than the TMD in reducing the floor vibration amplitude and improving the effective frequency suppression bandwidth, and for the same vibration suppression effect, the mass of the RIDTMD is much lighter than that of the TMD.

• 대한산업공학회지
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• 제27권2호
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• pp.197-202
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• 2001

The biomechanical analysis of the load carrying effect on different floor surfaces has been conducted. Four different floor surfaces were prepared for ten subjects with each walking at a fixed velocity(1.33 m/sec) while carrying five different loads. The results showed that because of the significant interaction effect between floor slipperiness and the load carrying task, the load carrying effect should be analyzed according to different levels of the floor slipperiness, especially contaminant floors. On oily surfaces, slip distance(SD) and heel velocity (HV) increased whereas stride length(SL) decreased as load increased. In other words, significantly longer SD, faster HV, and no normal gait were found as load increased. As a result, a different protocol should be applied to measure floor slipperiness on oily floors as compared to dry surfaces for tribological approach.

• 센서학회지
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• 제32권2호
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• pp.118-123
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• 2023

This study presents sensor system for autonomous mobile robot capable of floor-to-floor self-navigation. The robot was modified using the Turtlebot3 hardware platform and ROS2 (robot operating system 2). The robot utilized the Navigation2 package to estimate and calibrate the moving path acquiring a map with SLAM (simultaneous localization and mapping). For elevator boarding, ultrasonic sensor data and threshold distance are compared to determine whether the elevator door is open. The current floor information of the elevator is determined using image processing results of the ceiling-fixed camera capturing the elevator LCD (liquid crystal display)/LED (light emitting diode). To realize seamless communication at any spot in the building, the LoRa (long-range) communication module was installed on the self-navigating autonomous mobile robot to support the robot in deciding if the elevator door is open, when to get off the elevator, and how to reach at the destination.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
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• pp.109-114
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• 2009

The dominant heating system used in Korean residential apartment buildings is a hydronic radiant floor heating system, known as the Ondol system. The most common control strategy applied to this traditional hydronic radiant system is a simple on-off control that intermittently supplies "hot water of a fixed temperature" at a "constant flow rate" to each room. However, the current problems with the aforementioned control are as follows: (1) since the simple on-off control is usually based on a one point measured temperature (a signal from a thermostat installed in a living room) in each dwelling unit, heating energy use for unoccupied rooms as well as a difference in temperatures between spaces (master bedroom, living room, bedroom1, bedroom2) can occur occasionally. (2) the most widely used residential water splitter has static valves, and is thus not able to change the flow rate to each room depending on the space heating load. In other words, the ratio of flow rates to rooms is fixed after construction, resulting in over- or under-heating and an improper use of energy. The aim of this paper is therefore to investigate the differences in the system's performance between control strategies in terms of the flow rate control and sensor location. It is shown that energy savings of control strategies are strongly influenced by occupant schedule.

• Journal of Astronomy and Space Sciences
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• 제30권2호
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• pp.113-121
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• 2013

Heumgyeonggaknu is a water-hammering type automatic water clock which was made by Jang Yeong-Sil in 1438. The water clock that is located in Heumgyeonggaknu consists of Suho which is equipped with 2-stage overflow. Constant water wheel power is generated by supplying a fixed amount of water of Suho to Sususang, and this power is transferred to each floor at the same time. The 1st floor rotation wheel of Gasan consists of the operation structure which has the shape of umbrella ribs. The 2nd floor rotation wheel is made so that the 12 hour signal, Gyeong-Jeom signal, and Jujeon constitute a systematic configuration. The 3rd floor rotation wheel is made so that the signal and rotation of Ongnyeo and four gods can be accomplished. Based on the above conceptual design, this paper analyzed the internal signal generation and power transmission of Heumgyeonggaknu.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1992년도 춘계학술대회 논문집
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• pp.359-363
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• 1992

As the demands of manufacturing automation is increasing, lots of efforts are devoted to the applications of Computer Integrated Manufacturing(CIM) concept in manufacturing shop floor. A workstation is a computer which controls differnet machines in the low level of factory(shop floor). A workstation can be utilized efficiently to enhance the coopetative work of machines. A scheduler is a component program in a workstation and it controls the operation of machines according to a fixed plan. A scheme for the scheduler has been developed for selected machines and software has been made. The fixed plan is stored in a schedule file which keeps machine names, communications methods, information for communications and time for the usages, etc. The scheduler carries out its role by the information in the schedule file. Although the developed software has some Iimitations, the test results show that the scheduler can be applied easily to the automation of the low level of factory.

• KIEAE Journal
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• 제5권1호
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• pp.51-57
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• 2005

In this study, time-dependent concentration variations of VOCs from fixed furniture and Ondol floor widely used as finishing material of the floor were measured, and prediction equations were developed based on the measured results. VOCs were measured and analyzed based on EPA TO-17 and NIOSH 1500, 1501 method respectively, and GC/FID were used for the analysis of VOCs concentration. Measurements were carried out for 10 days after the installation of furniture and for 40 days after the installation of the floor in the residence constructed more than 10 years ago. In both case of floor and furniture installation, time-dependent concentration decay of VOCs can be properly converted into logarithmic scale. Especially in case of furniture, toluene showed the highest concentration and took longest time to decay. As a result of the prediction of VOCs concentration decay under different air change rate using estimated equations, concentration decay rate of indoor VOCs increased rapidly as the air change rate also increased.

• 한국실내디자인학회논문집
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• 제24권1호
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• pp.189-196
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• 2015

As the number of children's libraries has increased in Korea, it has been discussed to improve the quality of design in the libraries. In a reading room of children's library, spatial consideration should be focused on the children under 10 years old since they are in important points to learn Hangul and to develop reading habits. This study is aimed to examine the characteristics of a floor-sitting reading room, where children can feel like a home, stay in clean and safe and play while reading. The seven case studies of floor-sitting reading rooms are analyzed from the viewpoint of each factor of physical environment, including structure, furniture, and decoration. The following is the summary of findings of this study. First, floor-sitting reading rooms tend to compose main reading areas around bookshelves. Reading areas create the characters by changing floor levels and arranging furniture associated with windows, columns, and wall-type bookshelves. In the reading areas, movable low-level tables are frequently placed for flexible space uses, and seats for reading tend to put together with fixed bookshelves. Second, the central areas of the reading rooms are often shaped in the forms of pods, storytelling areas, sculptures, and unique furniture. Especially storytelling areas and pods play the cores of the reading rooms with the varying steps of floors and pictorial graphics on walls. Third, decoration elements in the reading rooms are designed with graphics, visual displays, and sculptural decorations. In my case studies, spatial elements such as reading nooks, attics, tunnels, and shelters are not often found in the floor-sitting reading rooms even though children like to have them. Since it is the advantage of floor-sitting reading rooms where children can take off shoes and act freely, we should look for the design of such spatial elements in the floor-sitting reading rooms.

• 신재생에너지
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• 제3권1호
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• pp.27-37
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• 2007

This study is to analyse the feasibility for providing Co-generation plant in Apartment Complex for 4 typical Apartment Complexes located Seoul metropolitan area, The selected complexes are three midium-large size Apartment[nearby 35pyoug of floor area] and one complex of small size Apartment[below 25 pyoung of floor area] for comparison. The necessary data for the study were collected with visitation of each site. The study showed very positive result for the three medium-large size Apartment Complexes of which the average floor area is more than 25 pyoungs, while negative result for the Complex of which average floor area is less than 25 pyoungs. Other than floor size it was found that the electric consumption density also influence the economic feasibility. In study the unit fixed cost of the energy produced from Co-generation plant is one third of the unit variable cost[fuel cost] and it seems better to select high thermal efficiency machine for Co-generation plant even with some higher cost of the plant.

• 대한산업공학회지
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• 제22권3호
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• pp.337-349
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• 1996

A study was conducted to find the possible relationship between slip distance and dynamic coefficient of friction (DCOF) through the biomechanical study of slips and falls using a broader variety of floors and levels of slipperiness than those used before. Four different floor surfaces covering the full range of floor slipperiness (with and without on oil contaminant) were prepared for ten subjects with each walking at a fixed velocity. The results showed that slip distance and heel velocity had a decreasing trend while stride length had a increasing trend as DCOF increased. The contaminant effect overpowered floor slipperiness effect because a higher DCOF surface with oil contaminant created longer slip distance than the lower DCOF with dry floor. Normal gait pattern and suggested heel velocity (10 to 20 cm/sec) were seen on dry floors but abnormally longer stride length and 5 to 10 times faster heel velocity were found an oily floors. In other words, faster heel velocity (greater than 10 to 20 cm/sec) is recommended to measure DCOF on oily floors because the assumption of normal gait was no longer valid.