• The KSFM Journal of Fluid Machinery
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• v.7 no.5 s.26
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• pp.13-19
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• 2004

Centrifugal blowers are widely used for air handling units in industry applications. The blower has a centrifugal impeller and a scroll casing including a driving component such as an electric motor. The impeller takes forward or backward blades to induce flows into the blower, Comprehensive investigation according to the two kinds of blades is systematically carried out for a guidance of design for this kind research. It is observed that flow rate of the blower with forward blades is larger than that of the system with backward blades. Otherwise, the system noise is more pronounced in the case of the blower with forward blades. The reason is due to larger velocity from the rotating forward blades that pose obtuse angle with the circumferential direction. The distinguished characteristics are validated by a parallel experiments with a wind tunnel and in an anechoic chamber. Numerical analysis for the system shows detail information inside the blades and the casing. A series of figures to show the flow details offer deep understanding of the performance of a centrifugal blower with different blades.

• Journal of Ocean Engineering and Technology
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• v.14 no.2
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• pp.89-98
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• 2000

Using conventional textile techniques such as weaving braiding knitting and stitching it is possible to produce a wide range two and three dimensional fiber preforms, however so far only a limited attention has been given to knitted fabrics in composite industry. This is mainly due to the opinion that knitted fabric reinforced composites posses low mechanical properties owing to their looped fiber architecture. But it is possible to obtain desired mechanical properties by selecting proper knitted fabric structure, In this paper mechanical characteristics of kevlar plain weft knitted fabrics reinforced plastics(KFRP) are evaluated for th development of intrusion beam of car side door. Tensile bending impact properties of KFRP are measured experimentally and crush demands of Americal Federal Motor Vehicle Safety Standard No.214(FMVSS 214) compared with the bending load and displacement of KFRP by quasi-static test method. The applicability and limitation of bending load and displacement of KFRP according to specimen size has been discussed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.289-292
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• 2005

PID controllers, which have been widely used in industry, have a simple structure and robustness to modeling error. But it is difficult to have uniformly good control performance in system parameters variation or different velocity command. In this paper, we propose an adaptive PID controller based on a gradient descent learning. This algorithm has a simple structure like conventional PID controller and robustness to system parameters variation. To verify performances of the proposed adaptive PID controller, the speed control of nonlinear DC motor is performed. The simulation results show that the proposed control systems are effective in tracking a command velocity under system parameters variation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.701-704
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• 2005

PID controllers, which have been widely used in industry, have a simple structure and robustness to modeling error. But They are difficult to have uniformly good control performance in system parameters variation or different velocity command. In this paper, we propose a nonlinear adaptive PID controller based on a cell-mediated immune response and a gradient descent learning. This algorithm has a simple structure and robustness to system parameters variation. To verify performances of the proposed nonlinear adaptive PID controller, the speed control of nonlinear DC motor is performed. The simulation results show that the proposed control systems are effective in tracking a command velocity under system parameters variation.

• Journal of Power Electronics
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• v.7 no.3
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• pp.222-232
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• 2007

This paper presents the application of a single phase AC-to-DC converter using a three-phase series parallel (SPRC) resonant converter to variable speed dc-drive. The improved power quality converter gives the input power factor unity over a wide speed range, reduces the total harmonic distortion (THD) of ac input supply current, and makes very low ripples in the armature current and voltage waveform. This soft-switching converter not only possesses the advantages of achieving high switching frequencies with practically zero switching losses but also provides full ranges of voltage conversion and load variation. The proposed drive system is the most appropriate solution to preserve the present separately excited de motors in industry compared with the use of variable frequency ac drive technology. The simulation and experimental results are presented for variable load torque conditions. The variable frequency control scheme is implemented using a DSP- TMS320LF2402. This control reduces the switching losses and current ripples, eliminates the EMI and improves the efficiency of the drive system. Experimental results confirm the consistency of the proposed approach.

• Journal of Fashion Business
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• v.10 no.6
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• pp.110-121
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• 2006

The purpose of this study is to analyze the various types and areas of recent collaborations in fashion industry and to find the utility value of collaboration. Seventy seven cases of fashion collaboration marketing strategies were selected from officially announced literature survey and enterprises information around the world. Among the seventy seven cases of fashion collaboration surveyed in this study, collaboration with other fields made up 59.7 percent, collaboration between the same fashion categories made up 40.3 percent. Among the areas of other fields, collaboration with IT(Information Technology) or Motor enterprises were included and made up 36.4 percent. Collaborations with Culture and art world that fashion brands collaborate with world-renowned industrial designer or artist and star entertainers were also included and made up 23.3 percent. Among the areas of the same categories, collaboration of fashion designer and sports or casual brand made up 22.1 percent. Collaborations of home shopping mall and fashion designer made up 18.2 percent. Collaboration cases surveyed in this study were classified according to three types; co-product development, co-branding, and co-marketing. Collaboration for co-product development made up 72.7 percent. Collaboration for co-branding made up 27.3 percent. Collaboration for co-marketing made up 37.7 percent. These collaboration marketing strategies are very efficient to upgrade brand image and cut the marketing cost by creating new target, product, brand, and promotion through successful partnerships. Therefore, much more various types and areas of fashion collaborations should be developed to create something new for future consumers.

• Korean Journal of Agricultural Science
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• v.48 no.3
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• pp.617-627
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• 2021

In the field of on-road motor vehicles, the level for autonomous driving technology is defined according to J3016, proposed by Society of Automotive Engineers (SAE) International. However, in the field of agricultural machinery, different standards are applied by country and manufacturer, without a standardized classification for autonomous driving technology which makes it difficult to clearly define and accurately evaluate the autonomous driving technology, for agricultural machinery. In this study, a method to classify the autonomy levels for autonomous agricultural machinery (ALAAM) is proposed by modifying the SAE International J3016 to better characterize various agricultural operations such as tillage, spraying and harvesting. The ALAAM was classified into 6 levels from 0 (manual) to 5 (full automation) depending on the status of operator and autonomous system interventions for each item related to the automation of agricultural tasks such as straight-curve path driving, path-implement operation, operation-environmental awareness, error response, and task area planning. The core of the ALAAM classification is based on the relative roles between the operator and autonomous system for the automation of agricultural machines. The proposed ALAAM is expected to promote the establishment of a standard to classify the autonomous driving levels of self-propelled agricultural machinery.

• Journal of Ocean Engineering and Technology
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• v.35 no.2
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• pp.150-160
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• 2021

To ensure the international competitiveness of the domestic offshore plant industry, a consensus has been formed regarding the requirement for large offshore basins for performing offshore plant performance verification. Accordingly, the Korea Research Institute of Ships & Ocean Engineering has built the world's largest deep ocean engineering basin (DOEB). The purpose of this study is to evaluate the characteristics of velocity distribution under various conditions of the DOEB. An independent measuring jig is designed and manufactured to measure the current velocities of many locations within a short time. The measurement jig is a 15-m-high triangular-truss structure, and the measurement sensors can move 15 m vertically through an electric motor-wire device. The current speed is measured under various impeller revolutions per minute and locations of the DOEB using the jig. The spatial distribution characteristics of the current velocity in the DOEB and the performance of the current generator are analyzed. The maximum speed is 0.56 m/s in the center of the DOEB water surface, thereby confirming sufficient current velocity distribution uniformity for model testing.

• Journal of the Semiconductor & Display Technology
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• v.22 no.3
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• pp.8-13
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• 2023

High bandwidth memory a core technology of the future memory semiconductor industry, is attracting attention. Temporary bonding and debonding process technology, which plays an important role in high bandwidth memory process technology, is also being studied. In this process, total thickness variation is a major factor determining wafer performance. In this study, the reliability of the equipment measuring total thickness variation is identified, and the servo motor settling, and wafer total thickness variation measurement accuracy are analyzed. As for the experimental variables, vacuum, acceleration time, and speed are changed to find the most efficient value by comparing the stabilization time. The smaller the vacuum and the larger the radius, the longer the settling time. If the radius is small, high-speed rotation performance is good, and if the radius is large, low-speed rotation performance is good. In the future, we plan to conduct an experiment to measure the entire of the wafer.

• Knowledge Management Research
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• v.21 no.3
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• pp.1-25
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• 2020

This study analyzed key success factors of Korean car-sharing enterprises, Socar and Greencar, and the responsive strategies of Korean car-manufacturing company, Hyundai Motor Group, in the face of emerging sharing economy under the specific economic and regulatory system in Korea. The outcomes of the analysis are as follows. 'Timely market entry' in early startup phase and 'use of external resources' in early growth phase were key success factors common to both Socar and Greencar. However, the differences in the eventual business directions of the two companies also resulted in different key success factors in the expansion phase of their business. For Socar which focused on maintaining its independence and the external growth of B2C business, customer relation marketing and sufficient capital raising were key success factors. For Greencar which became a part of a business group and focused on improving the efficiency of business operations, timely market entry (B2B market) was key success factor. The use of external resources and cooperation with large corporations emerged as key success factors common to both companies in the rapid growth phase. The responsive strategies of the Hyundai Motor Group were collaboration, investment and direct management of DeliveryCar. The short-term goal of the responsive strategy was the operation of test-bed in collaboration with car-sharing company while the mid/long term goal was planning new mobility services by utilizing collected data. Securing opportunities for early market dominance for autonomous car industry was also found to be an important goal.