• 한국소음진동공학회논문집
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• 제25권2호
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• pp.83-89
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• 2015

The transmission loss(TL) has been widely used as the acoustic performance index of industrial mufflers. Industrial mufflers usually consist of several partitions with perforated plate. In this study, firstly, the computational model for a typical industrial muffler was performed and validated by comparing with the experimental results. Secondly, the effects of the porosity of the perforated plates on the acoustical TL were investigated and the database of the tendencies were set up. Finally, on the basis of these tendencies, the modified muffler with better TL than conventional one could be suggested.

• 대한기계학회논문집B
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• 제21권10호
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• pp.1326-1338
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• 1997

Electrical characteristics of soot particles in a LPG diffusion flame were studied for the control of soot particle coagulation. When a DC voltage was applied between two electrodes installed parallel to gas flow, ionic wind effect caused soot deposition on the cathode, implying that most of the soot particles were positively charged. Soot deposit on the cathode linearly increased and was saturated with respect to the strength of the applied voltage. The possibility of applying an AC voltage to enhance the particle coagulation was then investigated and the efficiency of the size control was checked with transmission electron microscope photographs. For the amplitude of 2 kV AC field, primary (spherical) soot particle size decreased from 30 ~ 40 nm to around 20 nm when the frequency of the applied AC voltage was 60 Hz and higher. Collisions between the soot particles in such a selected AC condition could lead to the formation of much bigger agglomerates of roughly 1-5 .mu.m in size.

• 한국가스학회지
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• 제28권1호
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• pp.59-64
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• 2024

본 연구에서는 초소형 특수목적형 전기자동차에 적용 가능한 초소형 변속기에 대한 연구를 진행하였다. 일반적으로 전기자동차에서는 다단 기어형태의 변속기를 삭제하고 모터의 출력을 제어하거나 감속기를 통해 초기 구동력을 확보한다. 그러나 전기카트나 경형 전기자동차와 같은 초소형 차량에서는 배터리 용량이 상대적으로 적기 때문에 적재 상태에 따라 주행 거리가 감소하거나 모터에 부하가 가해질 수 있다. 따라서 본 연구에서는 CVT(Continuously Variable Transmission)의 변속 메커니즘을 적용하여, 구배 상태나 적재 상태와 같은 필요한 상황에서 변속이 가능한 고단 0.625와 저단1.6의 기어비를 갖는 2단 구조의 감속기를 개발하였다. 선정된 기어비를 기반으로 변속기를 설계하고, 개발된 변속기의 동력 전달 효율을 검증하기 위해 시험기를 제작하였다. 이 시험기를 통해 변속기의 회전 속도와 부하량을 변화시키며 동력 전달 효율 특성을 확인하고, 변속과 구동 시 발생되는 발열 특성도 확인하였다. 그 결과를 토대로 CVT구조를 갖는 2단 구조의 변속기를 개발하였다.

• The Korean Journal of Physiology and Pharmacology
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• 제27권1호
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• pp.39-48
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• 2023

Spinal nerve injury causes mechanical allodynia and structural imbalance of neurotransmission, which were typically associated with calcium overload. Storeoperated calcium entry (SOCE) is considered crucial elements-mediating intracellular calcium homeostasis, ion channel activity, and synaptic plasticity. However, the underlying mechanism of SOCE in mediating neuronal transmitter release and synaptic transmission remains ambiguous in neuropathic pain. Neuropathic rats were operated by spinal nerve ligations. Neurotransmissions were assessed by whole-cell recording in substantia gelatinosa. Immunofluorescence staining of STIM1 with neuronal and glial biomarkers in the spinal dorsal horn. The endoplasmic reticulum stress level was estimated from qRT-PCR. Intrathecal injection of SOCE antagonist SKF96365 dose-dependently alleviated mechanical allodynia in ipsilateral hind paws of neuropathic rats with ED₅₀ of 18 ㎍. Immunofluorescence staining demonstrated that STIM1 was specifically and significantly expressed in neurons but not astrocytes and microglia in the spinal dorsal horn. Bath application of SKF96365 inhibited enhanced miniature excitatory postsynaptic currents in a dosage-dependent manner without affecting miniature inhibitory postsynaptic currents. Mal-adaption of SOCE was commonly related to endoplasmic reticulum (ER) stress in the central nervous system. SKF96365 markedly suppressed ER stress levels by alleviating mRNA expression of C/ EBP homologous protein and heat shock protein 70 in neuropathic rats. Our findings suggested that nerve injury might promote SOCE-mediated calcium levels, resulting in long-term imbalance of spinal synaptic transmission and behavioral sensitization, SKF96365 produces antinociception by alleviating glutamatergic transmission and ER stress. This work demonstrated the involvement of SOCE in neuropathic pain, implying that SOCE might be a potential target for pain management.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.470-475
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• 2001

The elevator gear box with the helical gears needs to be developed instead of the one with the worm gears to improve the efficiency. In order to develop the gear box, the analytical tool to predict the helical gear noise is necessary to meet customer's noise requirement. Gear noise is related to the loaded transmission error. Therefore, the simulation program for the loaded transmission error analysis of the helical gears is developed in this study. Using the developed program, the effects of tooth modification such as tip relief and the extent of tip relief are investigated. Finally, the procedures to determine the tip relief and the extent of tip relief are proposed.

• 한국멀티미디어학회논문지
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• 제17권6호
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• pp.687-696
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• 2014

An integrated ship area network has functionality of remote control and autonomous management of various sensors and instruments embedded or boarded in a ship. For such environment, an wireless bridge is essential to transmit control and/or managing information to sensors or instruments from a central integrated ship area network station. In this paper, one of reliable schemes of WiMedia based wireless bridge using relay cooperative transmission using WiMedia distributed MAC protocol is proposed to increase a communication reliability between cluster headers, irrespective of channel variation. Simulation results show that the proposed wireless bridge using relay cooperative transmission scheme increases communication reliability.

• 한국정밀공학회지
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• 제25권9호
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• pp.71-77
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• 2008

Microcellular foaming plastics create a sensation at polymer industrial for lowering product costs and overcoming a lowering of mechanical intensity. Among many advantages, microcellular foaming plastics is well known to have a good acoustical properties. This research based on the experiment of sound absorption and transmission characteristics inquire into acoustical properties of microcellular foaming plastics. Difference of transmission loss of microcellular foaming plastics and solid materials was defined as cell effect. Also, cell effect is expressed by sound reflection and sound absorption. This study is expected to fundamental research to present economical, functional alternative plan for products using sound absorption and transmission materials.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.712-717
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• 2007

This study deals with the TE(Transmission Error) of gear tooth profile by modifying a profile and lead of a surface of tooth. First, we experimentally confirmed that the TE is a synthesis of the sliding velocity between both gears. Since various types of TE appear in the experiments, we introduced definition of transmission error and the optimism design by modifying a surface parameters. The test stand's performance is then evaluated through a series of multiple torque transmission error tests. Comparisons are made between data recorded before and after the test stand's redesign, and subsequently repeatability studies are performed to verify the veracity of the measured data. Finally, the experimental results are compared to the analytical predictions of two different gear analysis programs.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1069-1074
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• 2007

TRIZ is innovative problem solving methodology. It can solve problems by systematical and convergent method, not by the existing divergent method like 'Brainstorming'. In this paper, TRIZ is used for reduction noise from gear in transmission. In order to reduce gear noise, design resources is derived first. According to the derived idea, level and function of system can be defined. After that, we suggest a way to reduce the noise from gear in transmission using 40 Principles and Substance-field analysis of TRIZ.

• International Journal of Precision Engineering and Manufacturing
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• 제3권3호
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• pp.28-36
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• 2002

The continuously variable transmission (CVT) mechanism considered here is the output coupled type which combines the functions of a 2K-H I type differential gear unit and a V-belt type continuously variable unit (CVU). One shaft of the CVU is connected directly to the output shaft and another shaft of it is linked to the differential gear unit. It is shown that some fundamental relations (speed ratios, power flows and efficiencies) for twelve mechanisms previously described are valid by various experimental studies, six of them produce a power circulation and the others produce a power split. Parametric analysis is carried out in relation to the efficiency, speed ratio and power ratios in order to assist in the design of an optimum configuration. Some useful properties associated with power flow modes also are discussed in the output coupled type continuously variable transmission.