• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.13 no.5
• /
• pp.327-333
• /
• 2003

Several tests are performed to evaluate road booming noise. Baseline test delivers the information of road noise characteristics. Coupling effect between structure and acoustics is obtained from the mode shapes and the natural frequencies by the modal test. Equivalent stiffness at joint areas between chassis and car-body system can be determined by the input point inertance test. Noise sensitivity of body mounting point of a chassis part can be obtained from the noise transfer function test with input point inertance test. Operational deflection shape makes us analyze the actual vibration modes of the chassis system under actual leading and find noise sources very easily. Finally, the transfer path analysis is used to Identify noise Paths through the chassis system. The objectives and the procedures of the tests are described in this Paper Also, the guideline for efficient road noise evaluation test can be found.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.5
• /
• pp.2628-2634
• /
• 2014

Vehicle washer heater system is more widely adopted to defrost a window or to clear the windshield glass in winter season. The washer heater system should be designed to heat up washer fluid rapidly to the target temperature for only a short time. A numerical analysis has been carried out to analyze the heat transfer characteristics with materials of inside parts in vehicle washer heater system with filler and flow path. ANSYS - FLUENT software is employed for the analysis. The axial symmetry model is three-dimensional and unsteady. It applies to the coupled method which is one of pressure based. Through this result, it was obtained to find the optimal material condition for the filler and flow path in washer system. For material of filler, the air with lower density was heated more rapidly rather than silicon carbide(SiC). For material of flow path, copper with the heat transfer coefficient of approximately four times greater than the nickel gives us higher efficiency. That is the reason why the heating time of methanol was reduced to make uniform temperature in washer heater system.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.12
• /
• pp.117-124
• /
• 2008

In early design stage, the simulation of interior noise is useful for the enhancement of the noise, vibration and harshness (NVH) performance in a vehicle. The traditional transfer path analysis (TPA) technology cannot simulate the interior noise since it uses the experimental method. In order to solve this problem, in this paper, the hybrid TPA is developed as the novel approach. The hybrid TPA uses the simulated excitation force as the input force, which excites the flexible body of a car at the mount point, while the traditional TPA uses the measured force. This simulated force is obtained by numerical analysis for the FE (finite element) model of a powertrain. The interior noise is predicted by multiplying the simulated force by the vibro-acoustic transfer function (VATF) of the vehicle. The VATF is the acoustic response in the compartment of a car to the input force at the mount point of the powertrain in the flexible car body. The trend of the predicted interior noise based on the hybrid TPA very well corresponds to the measured interior noise, although there is some difference due to not only the experimental error and the simulation error but also the effect of the air-borne path.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.15 no.12
• /
• pp.1043-1048
• /
• 2003

An experimental investigation was executed to determine the capacity degradation due to non-uniform refrigerant distribution in a multi-path evaporator. In addition, the possibility of recovering the capacity reduction by controlling the refrigerant distribution among refrigerant paths was assessed. The finned-tube evaporator, which had a three-path and three-depth-row, was tested by controlling inlet quality, exit pressure, and exit superheat for each refrigerant path. The capacity reduction due to superheat unbalance between each path was as much as 30%, even when the overall evaporator superheat was kept at a target value of 5.6$^{\circ}C$. It may indicate that the internal heat transfer within the evaporator assembly caused the partial capacity drop. For the evaporator having air mal-distributions, the maximum capacity reduction was found to be 8.7%. A 4.5% capacity recovery was obtained by controlling refrigerant distribution to obtain the target superheat at the outlet of each path.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.607-613
• /
• 2011

This paper reviews search methods of multiple reasonable paths to implement multimodal public transportation network of Seoul. Such a large scale multimodal public transportation network as Seoul, the computation time of path finding algorithm is a key and the result of path should reflect route choice behavior of public transportation passengers. Search method of alternative path is divided by removing path method and deviation path method. It analyzes previous researches based on the complexity of algorithm for large-scale network. Applying path finding algorithm in public transportation network, transfer and loop constraints must be included to be able to reflect real behavior. It constructs the generalized cost function based on the smart card data to reflect travel behavior of public transportation. To validate the availability of algorithm, experiments conducted with Seoul metropolitan public multimodal transportation network consisted with 22,109 nodes and 215,859 links by using the deviation path method, suitable for large-scale network.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.11a
• /
• pp.267-271
• /
• 1996

In this study, performance improvement of the inverse modeling as the on-line control method for the estimation, control experiment is performed. As the modeling errors is occurred in duct system arbitrarily, a case using the filtered-x LMS algorithm only as the control method, a case using tile inverse modeling method only and a case using the inverse modeling with the adaptive line enhancer are compared. The estimation errors between real secondary path transfer functions and the estimated and the control performances of primary noises with these estimated transfer functions are compared.

• Journal of Distribution Science
• /
• v.14 no.9
• /
• pp.121-132
• /
• 2016

Purpose - This study has the following objectives. First, it seeks to build an integrated model that can analyze the path through which headquarters, subsidiary competence, and knowledge transfer performance influence subsidiary performance. Second, it analyzes the influence of the specificity of technology as a moderating effect factor on knowledge transfer process. Third, it will conduct an empirical analysis on distributive manufacturing MNEs and suggests an implication for companies that actually need technological localization. The difference of this study are as follows. First, unlike the existing studies, this study can expand a theoretical discussion as it uses subsidiary performance as the dependent variable. Second, it sets the specificity of technology as a moderating effect factor, not an antecedent, and can draw a theoretical implication. Research design, data, and methodology - This study built a path analysis model to identify the influence of the disseminative capacity and absorptive capacity of distributive manufacturing MNEs on subsidiary performance. Based on the previous studies, it set 19 items as 5 latent variables, and established 6 hypotheses by including the moderating effect of the specificity of technology between them. The final 203 companies were selected as analysis samples through a survey questionnaire. For empirical analysis, the study used PLS (Partial Least Square) that is based on structural equation model. Results - The empirical analysis result demonstrated that both headquarters' disseminative capability and subsidiaries absorptive capacity had a positive influence on knowledge transfer performance. Knowledge transfer performance also had a positive influence on subsidiary performance. In the analysis of moderating effect, the specificity of technology acted as a significant moderating variable only between knowledge transfer performance and subsidiary performance; it did not show a statistically significant moderating effect among disseminative capability, absorptive capacity, and knowledge transfer performance. Conclusions - The empirical analysis results of this study demonstrate the importance of disseminative capability and absorptive capacity in knowledge transfer to subsidiaries from the distributive manufacturing MNEs in Korea. The analysis on the moderating effect indicates that the specificity of technology in Korean companies influences on the process of making achievement by using the transferred knowledge.

• Journal of the Optical Society of Korea
• /
• v.6 no.3
• /
• pp.121-127
• /
• 2002

The operating principal of a ring laser gyroscope depends on the phase difference for the counter-propagating waves within a closed path. The reflecting mirrors mounted on the monoblock form the traveling waves. The manufacturing accuracy of the monoblock influences the traveling path of ray, the sensitivity of laser resonator for misalignments, and diffraction losses. A 3 $\times$ 3 ray transfer matrix was derived for optical components with centering and squaring errors in a ring resonator. The matrix can be utilized to predict the optical ray paths on the basis of the manufacturing errors of the monoblock as well as the misalignment of mirrors. Then the distance and orientation (o. slope) at the arbitrary plane inside the resonator along the ideal optical path can be calculated from the chain multiplication of the ray transfer matrix for each optical component in one round trip. We also show that the counter-propagating rays In a ring resonator with errors does not coincide in each round trip, which results in gain difference between two beams, and how these errors can be adjusted through the alignment procedure. Finally this 3 $\times$ 3 ray matrix formalism can be used to calculate the beam size and its displacement from the optical axis and the deviation at the diaphragm.

• Industrial Engineering and Management Systems
• /
• v.15 no.1
• /
• pp.19-31
• /
• 2016

A design method of the network for automated transporters mounted on rails is addressed for automated container terminals. In the network design, the flow directions of some path segments as well as routes of transporters for each flow requirement must be determined, while the total transportation and waiting times are minimized. This study considers, for the design of the network, the waiting times of the transporters during the travel on path segments, intersections, transfer points below the quay crane (QC), and transfer points at the storage yard. An algorithm, which is the combination of a modified Dijkstra's algorithm for finding the shortest time path and a queuing theory for calculating the waiting times during the travel, is proposed. The proposed algorithm can solve the problem in a short time, which can be used in practice. Numerical experiments showed that the proposed algorithm gives solutions better than several simple rules. It was also shown that the proposed algorithm provides satisfactory solutions in a reasonable time with only average 7.22% gap in its travel time from those by a genetic algorithm which needs too long computational time. The performance of the algorithm is tested and analyzed for various parameters.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.556-559
• /
• 1997

In this paper, we propose a cooperative multi-robot control algorithm. Specifically, the cooperative task is that two mobile robots should transfer a long rigid object along a predefined path. To resolve the problem, we introduce the master-slave concept for two mobile robots, which have the same structure. According to the velocity of the master robot and the positions of two robots on the path, the velocity of the slave robot is determined. In case that the robots can't move further, the role of the robot is interchanged. The effectiveness of this decentralized algorithm is proved by computer simulations.