• 한국구조물진단유지관리공학회 논문집
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• 제26권3호
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• pp.39-47
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• 2022

국내의 공동주택 보급률 증가에 따라 층간소음으로 인한 문제가 증가하고 있다. 이를 예방하기 위하여 바닥 충격음 차단 구조에 대한 수요가 높아지고 있으며 해당 구조에 대한 성능 인증이 이뤄지고 있지만 소음 차단 성능이 현장에서는 재현되지 않는다는 문제점이 있다. 해당 구조가 제 성능을 발휘하기 위해서는 일정 두께 이상의 마감 모르타르 타설이 필요하며, 해당 구조의 시공 적정성 판정을 위하여 GPR을 이용한 두께 측정 실험을 진행하였다. 본 연구에서 개발한 두께 측정 알고리즘은 측정된 데이터를 기반으로 상대유전율을 설정할 수 있어 정확한 두께 값을 측정할 수 있다. 네 종류의 바닥 충격음 차단 인증 구조에서 GPR 두께 측정 실험을 진행하였으며, GPR 데이터와 천공 측정 데이터 간 평균 오차는 1.95mm로 나타났다. 또한 마감재 유무가 측정값에 미치는 영향을 조사하기 위하여 총 3가지 종류의 마감재를 배치하고 실험을 진행으며, 평균 오차는 1.70mm로 나타났다. 추가적으로 장비의 샘플링 오차, 개발 알고리즘 변수, 천공 오차등을 종합적으로 고려하였을 때, GPR 계측 및 제안 알고리즘은 매우 높은 정확도로 슬래브 마감 모르타르의 두께 측정에 적용할 수 있음을 확인하였다.

• 전자공학회논문지SC
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• 제48권4호
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• pp.47-53
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• 2011

전동차 출입문은 포켓 슬라이딩 도어, 아웃 슬라이딩 도어, 플러그 도어로 구분된다. 현재 국내 전동차의 표준규격으로 제시되어 있는 포켓 슬라이딩 도어는 철도차량이 고속화됨에 따라 소음 및 외풍의 차단이 어려운 단점이 있으며, 아웃 슬라이딩 도어 역시 소음 및 외풍차단이 어려운 시스템이다. 반면에 플러그 도어는 최근 철도차량이 고급화됨에 따라 고속철도에 적용되던 출입문을 전동차에 적용하면서 쓰이게 된 도어시스템으로 승차감 개선에 소음이 중요한 위치를 차지함에 따라 소음에 강한 플러그 도어 시스템이 주목받고 있다. 이러한 이유로 차세대전동차에 적용할 목적으로 전기식 플러그 도어를 개발하여 시험 진행 중에 있다. 플러그 도어를 구성하는 하부 부품으로는 출입문 제어 장치 (DCU : Door Control Unit), 모터, 스크루 기어, 볼 너트, 레일, 리미트 스위치, 각종 전기 장치, 비상 수동 개폐장치, 코디네이션 바 등이 있는데 이중 DCU는 전동차 출입문을 개폐하기 위한 제어장치로 량당 8개인 전동차 출입문이 동시에 열리고 닫히기 위해서는 각 출입문간의 인터페이스가 필요하며, 승객의 승하차와 직접적으로 관련되어 있기 때문에 신뢰성 및 안전성 확보가 매우 중요한 시스템이다. DCU의 기능으로는 자동 문 여닫음 제어, 출입문 제어 및 장애 감지, 출입문 상태 제어, 저전압/고전압 감시 등이 있으며, 본 논문에서는 전기식 플러그 도어에 적용하기 위해 개발된 DCU의 기능, 개발요구사양, 시스템 구성 및 시험결과에 대해 논하고자 한다.

• International Journal of Aeronautical and Space Sciences
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• 제12권2호
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• pp.93-114
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• 2011

The current status of Canadian research on rotor-based actively controlled technologies for helicopters is reviewed in this paper. First, worldwide research in this field is overviewed to put Canadian research into context. Then, the unique hybrid control concept of Carleton University is described, along with its key element, the "stiffness control" concept. Next, the smart hybrid active rotor control system (SHARCS) projected's history and organization is presented, which aims to demonstrate the hybrid control concept in a wind tunnel test campaign. To support the activities of SHARCS, unique computational tools, novel experimental facilities and new know-how had to be developed in Canada, among them the state-of-the-art Carleton Whirl Tower facility or the ability to design and manufacture aeroelastically scaled helicopter rotors for wind tunnel testing. In the second half of the paper, details are provided on the current status of development on the three subsystems of SHARCS, i.e. that of the actively controlled tip, the actively controlled flap and the unique stiffness-control device, the active pitch link.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권11호
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• pp.561-568
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• 2005

This paper proposes a method that distributes the load power and stores the regenerated energy for a hoist-load system using the supercapacitor, an energy storage device. The crane, which is a representative hoist-load system, operates in two modes. The first is the hoist-up mode in which the load container is lifted up: the maximum power is required at the end of acceleration. The second is the hoist-down mode in which the load container is lifted down; the regenerated energy is wasted by the resistor In this paper, the supercapacitor stores the regenerated energy in the hoist-down operation and supplies the peak power demand in the hoist-up operation. The same structure as the commercially available three-phase inverter is proposed as a bidirectional do-dc converter to charge and discharge the supercapacitor. A power control algorithm is proposed to optimize the load sharing between the generator and the supercapacitor. Using the proposed method, it is effected that the generator size can be cut down to one third of the original one; it leads to the reduction of the fuel consumption, noise and air pollution. Simulation and experimental results verify the effectiveness of the Proposed method.

• Structural Engineering and Mechanics
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• 제36권5호
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• pp.561-573
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• 2010

The potential of the liquid column vibration absorber (LCVA) as a seismic vibration control device for structures has been explored in this paper. In this work, the structure has been modeled as a linear, viscously damped single-degree-of-freedom (SDOF) system. The governing differential equations of motion for the damper liquid and for the coupled structure-LCVA system have been derived from dynamic equilibrium. The nonlinear orifice damping in the LCVA has been linearized by a stochastic equivalent linearization technique. A transfer function formulation for the structure-LCVA system has been presented. The design parameters of the LCVA have been identified and by applying the transfer function formulation the optimum combination of these parameters has been determined to obtain the most efficient control performance of the LCVA in terms of the reduction in the root-mean-square (r.m.s.) displacement response of the structure. The study has been carried out for an example structure subjected to base input characterized by a white noise power spectral density function (PSDF). The sensitivity of the performance of the LCVA to the coefficient of head loss and to the tuning ratio have also been examined and compared with that of the liquid column damper (LCD). Finally, a simulation study has been carried out with a recorded accelerogram, to demonstrate the effectiveness of the LCVA.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2427-2429
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• 2005

OLED in the spotlight of display market has advantages of low power driving, self-emission and fast response. But it has disadvantages of inefficient luminescence and high power consumption. Most of PM(passive Matrix) DC-DC converters in common use is using voltage divider. This voltage divider type has some difficulties of suitable electric device selection for voltage division and of the stabilized output due to feedback current trimming. Therefore, noise analysis and power solution in OLED are important technologies having an effect on electric characteristics. In this dissertation, we have obtained the stable output by using digital signals in multi-channel DC-DC converter, the profit of power consumption reduction of driving source and economical efficiency in the PCB board size.

• 한국기계가공학회지
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• 제18권9호
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• pp.72-80
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• 2019

In this task, the tool dynamometer design and manufacture, and the Ansys S/W structural analysis program for tool attachment that satisfies the cutting force measurement requirements of the tool dynamometer system are used to determine the cutting force generated by metal cutting using 3-axis static structural analysis and the LabVIEW system. The cutting power in a cutting process using a milling tool for processing metals provides useful information for understanding the processing, optimization, tool status monitoring, and tool design. Thus, various methods of measuring cutting power have been proposed. The device consists of a strain-gauge-based sensor fitted to a new design force sensing element, which is then placed in a force reduction. The force-sensing element is designed as a symmetrical cross beam with four arms of a rectangular parallel line. Furthermore, data duplication is eliminated by the appropriate setting the strain gauge attachment position and the construction of a suitable Wheatstone full-bridge circuit. This device is intended for use with rotating spindles such as milling tools. Verification and machining tests were performed to determine the static and dynamic characteristics of the tool dynamometer. The verification tests were performed by analyzing the difference between strain data measured by weight and that derived by theoretical calculations. Processing test was performed by attaching a tool dynamometer to the MCT to analyze data generated by the measuring equipment during machining. To maintain high productivity and precision, the system monitors and suppresses process disturbances such as chatter vibration, imbalances, overload, collision, forced vibration due to tool failure, and excessive tool wear; additionally, a tool dynamometer with a high signal-to-noise ratio is provided.

• 기술사
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• 제19권2호
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• pp.10-20
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• 1986

전압외란(voltage disturbances)에 대하여 민감함 전기전자기기가 받는 영향을 최소화하기 위한 방안으로 전력공급자측에서의 대책과 수용가기기에서의 대응책에 대하여 조사연구하였다. 전력공급자에서의 대책으로는 전압강하 시간의 단축에 대하여 검토하였는데, 효과와 경제성으로 보아 실현가능성이 적었다. 수용가기기에서의 대응책으로는 컴퓨터제어(computer control)와 자동화시스템(automated systems) 등에는 무정전 전원장치 또는 노이즈 서프레서(noise suppressor)나 파워콘디쇼너(power conditioners)를 설치하고, 전자개폐기는 지연석방형 전자개폐기를 채용하며, 가변속제어전동기에는 순간전압부하에 대한 대책이 고려된 제어회로를 채용하고, 고압방전등에는 순간재점등장치가 붙은 등기구를 채용하며, 부족전압계전기는 계전기의 정전시감을 연장하는 방안과 순간정전시에는 자동으로 재투입하는 sequence를 구성하는 방법등이 효과적인 대책으로 검토되었다.

• 한국소음진동공학회논문집
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• 제23권5호
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• pp.385-393
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• 2013

In this paper, the mechanism identification and the avoidance measures on the phenomena of transient acoustic vibration amplified at the water-supply piping system to regulate the steam temperature of the boiler reheater in 500MW class supercritical power plant are presented. The pressure pulsation waves induced by the impeller passing of two feed-water pumps with five blades are coincident with the local acoustic modes of boiler reheater water-supply piping system. There are the phenomena amplified at the peaks of 5X, 10X, 15X and 20X in spectrums of piping vibration, sound pressure, and the feed-water's pressure pulsation waves. The shut-off device is installed in the piping system for the interception of pressure pulsation waves transmitted from two feed-water pumps and the modified design change of the piping layout is applied for the acoustic resonance avoidance. The acoustic natural frequencies are separated from the harmonics of pressure pulsation waves induced by the pump impellers passing through the design change of the span length. The acoustic vibration is gone by resonance avoidance measures. As a result, more than 20 dBA reduction is achieved from 100 dBA to 80 dBA.

• Journal of Acupuncture Research
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• 제27권1호
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• pp.75-86
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• 2010

Objectives : We developed and proposed a guideline for safety and performance assessment of electric moxibustion apparatus (class II medical device). Methods : We drafted the guideline for safety and performance assessment of electric moxibustion apparatus by referring the existing standards, guidelines and measurement data from commercially available products. Temperature characteristics such as maximum temperature and ramp time, and physical characteristics such as weight, noise and diameter were measured. User friendliness was also evaluated for commercial devices. Results : This guideline only can be applied to the electric moxibustion apparatus where moxa is being heated by electricity for medical proposes. Maximum temperature of higher than $50^{\circ}C$ can be achieved mostly. Ramp rate of temperature seems to be reliable. Control of temperature is needed to be improved. Moxa and its derivative products seem to be regulated for reliable temperature performance for clinical application. Requirements for design and development of electric moxibustion apparatus are suggested : temperature indicator, temperature control and its accuracy, safety measure, surge protection, user friendliness and instruction for use (IFU). Design recommendation of the reduction of noise level and energy loss are suggested for better products. Conclusions : We proposed a guideline for safety and performance assessment of electric moxibustion apparatus to improve the quality of relating products and aid their commercialization by aiming higher industrial competitiveness of the medical device sectors in Korea. Discussion with related institutes such as industry, academy and government is further required. Public hearings also need to be held prior to the establishment of a final guideline and standard.