• Journal of Welding and Joining
• /
• v.26 no.6
• /
• pp.59-66
• /
• 2008

Recently, automobile parts progress with modularization, which a great many allied products are modularized. Therefore, the purpose of this study is to develope modular housing for modularization of steering gear. Generally, steering gear housing is composed of valve housing and rack housing, it is important to combine two housings. However, housing having the pipe shape is very sensitive to welding distortion, and welding trajectory is very complicated. In order to solve this subject, cooperative control by using robots was constructed. Further, we developed the dedicated system to suit modular housing based on it, and applied laser welding to there. Moreover, welding speed was controlled in the rapid curve section so that the defect in trajectory of housing was reduced to obtain sound weldment. Accordingly, produced housing by this way is presented enough withstanding pressure to $100kg/cm^2$, and roundness and straightness are measured about 10/100 and 0.9/100 respectively.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.1
• /
• pp.126-134
• /
• 2000

Version control is an application to maintain consistency between different instances of the same document allowing operations such as navigation, differencing, and merging. Most version control systems, however, lack the support of functionality for cooperative writing environment, such as to represent and store the history of the actions of different individuals, to effectively differentiate and merge the individual actions including the text object, and to manage different access privileges for different granularity and individuals. With the help of Activity IDentification (AID) tag and its unique addressing scheme proposed in this paper, differencing and merging become simple and effective. Access and role control is improved by associating the access right table and role assignment in AID scheme also eliminates the requirements for large storage capacity for version information maintenance.

• Journal of the Korean Society of Industry Convergence
• /
• v.22 no.2
• /
• pp.137-146
• /
• 2019

This study proposed a new technique to control of mobile robot based on voice command for (Human-Robot Cooperative operation in manufacturing precess). High performance voice recognition and control system was designed In this paper for smart factory. robust voice recognition is essential for a robot to communicate with people. One of the main problems with voice recognition robots is that robots inevitably effects real environment including with noises. The noise is captured with strong power by the microphones, because the noise sources are closed to the microphones. The signal-to-noise ratio of input voice becomes quite low. However, it is possible to estimate the noise by using information on the robot's own motions and postures, because a type of motion/gesture produces almost the same pattern of noise every time it is performed. In this paper, we describe an robust voice recognition system which can robustly recognize voice by adults and students in noisy environments. It is illustrated by experiments the voice recognition performance of mobile robot placed in a real noisy environment.

• Journal of Institute of Control, Robotics and Systems
• /
• v.21 no.9
• /
• pp.898-902
• /
• 2015

Alternative radio-navigation technologies aim at providing continuous navigation solution even if one cannot use GNSS (Global Navigation Satellite System). In shadowing region such as indoor environment, GNSS signal is no longer available and the alternative navigation system should be used together with GNSS to provide seamless positioning. For soldiers in battlefield where GNSS signal is jammed or in street battle, the alternative navigation system should work without positioning infrastructure. Moreover, the radio-navigation system should have scalability as well as high accuracy performance. This paper presents a TWR (Two-Way-Ranging)-based cooperative positioning system (CPS) that does not require location infrastructure. It is assumed that some members of CPS can obtain GNSS-based position and they are called mobile anchors. Other members unable to receive GNSS signal compute their position using TWR measurements with mobile anchors and neighboring members. Error propagation in CPS is analytically studied in this paper. Error budget for TWR measurements is modeled first. Next, location error propagation in CPS is derived in terms of range errors. To represent the location error propagation in the CPS, Location Error Propagation Indicator (LEPI) is proposed in this paper. Simulation results show that location error of tags in CPS is mainly influenced by the number of hops from anchors to the tag to be positioned as well as the network geometry of CPS.

• Journal of The Korean Association For Science Education
• /
• v.20 no.4
• /
• pp.519-526
• /
• 2000

In this study, the effects of visual organization and cooperative learning in problem-solving strategy were investigated. Three classes (N=127) at a high school were assigned to SV (Strategy-Visual organization) group, SVC (Strategy-Visual organization-Cooperative learning) group, and control group. After instructions, students' multiple-choice problem-solving ability, strategy performing ability, anxiety about chemistry learning, perception of involvement, and motivation to learning science were examined. Although multiple-choice problem-solving ability was not different significantly, there was a significant main effect in strategy performing ability. The scores of the SV and SVC groups were significantly higher than those of the control group, especially in the subcategories of problem understanding and recalling related principles. In the tests of perception of involvement and motivation to learning science, the scores of the SV and SVC groups were also significantly higher than those of the control group. However, problem-solving strategy using visual organization could not alleviate anxiety about chemistry learning.

• Geomechanics and Engineering
• /
• v.18 no.4
• /
• pp.439-448
• /
• 2019

The bearing capacity of roadside support is the key problem in gob-side entry retaining technology. To study the cooperative bearing characteristics of the roof-roadside support-floor along the gob-side entry retaining, a mechanical model of the composite structure of the roof-roadside support-floor was first established. A method for determining the structural parameters of gob-side entry retaining was then proposed. Based on this model, adaptability analysis of roadside support was carried out. The results showed that the reasonable width of the gob-side entry roadway was inversely proportional to the mining height, and directly proportional to the bearing strength of the roof and floor. And the reasonable width of the "flexible-hard" roadside support was directly proportional to its own strength, and inversely proportional to the width of the gob-side entry retaining. When determining the position and size of the roadside support along the gob-side entry retaining, the surrounding rock environment should be fully considered. Measured results from case study also show the rationality of the model and calculation method.

• Food Science of Animal Resources
• /
• v.36 no.1
• /
• pp.90-99
• /
• 2016

This study evaluated the effects of two Korean traditional plant extracts (Diospyros kaki THUNB. leaf; DK, and Nelumbo nucifera leaf; NN) on the fermentation, functional and sensory properties of herbal yogurts. Compared to control fermentation, all plant extracts increased acidification rate and reduced the time to complete fermentation (pH 4.5). Supplementation of plant extracts and storage time were found to influence the characteristics of the yogurts, contributing to increased viability of starter culture and phenolic compounds. In particular, the increase in the counts of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus was highest (2.95 and 1.14 Log CFU/mL respectively) in DK yogurt. Furthermore, supplementation of the plant extracts significantly influenced to increase the antioxidant activity and water holding capacity and to produce volatile compounds. The higher antioxidant activity and water holding capacity were observed in NN yogurt than DK yogurt. Moreover, all of the sensory characteristics were altered by the addition of plant extracts. Addition of plant extracts increased the scores related to flavor, taste, and texture from plain yogurt without a plant extract, as a result of volatile compounds analysis. Thus, the overall preference was increased by plant extracts. Consequently, supplementation of DK and NN extracts in yogurt enhanced the antioxidant activity and physical property, moreover increased the acceptability of yogurt. These findings demonstrate the possibility of using plant extracts as a functional ingredient in the manufacture of herbal yogurt.

• Journal of the Korean Chemical Society
• /
• v.57 no.3
• /
• pp.389-397
• /
• 2013

In this study, the effects of STAD cooperative learning strategy on students' achievement, learning motivation, perceptions of learning environment, and perceived classroom goal structure were investigated in terms of students' collectivism level. Two classes (64 students) from an elementary school were respectively assigned to a control group and a treatment group. A individualism-collectivism test, a learning motivation test, a perceptions of learning environment test, and a perceived classroom goal structure test were administered as pretests. The intervention of cooperative learning lasted for 24 class periods. After instruction, an achievement test, the learning motivation test, the perceptions of learning environment test, and the perceived classroom goal structure test were administered. The results indicated that the students of the treatment group significantly outperformed those of the control group in the achievement test. There was a significant treatment-aptitude interaction effect in the scores of the attention subcategory of the learning motivation. In the perceptions of learning environment, the score of the treatment group was significantly higher than the control group in the cohesiveness subcategory, whereas the score of the treatment group was significantly lower than their counterpart in the competitiveness subcategory. It was also found that the score of the treatment group was significantly higher than the control group in the performance subcategory of the perceived classroom goal structure.

• Journal of Institute of Control, Robotics and Systems
• /
• v.20 no.12
• /
• pp.1181-1188
• /
• 2014

In this paper, we propose a novel concept foran unmanned delivery service using a cooperative heterogeneous unmanned system consisting of a self-driving car and an unmanned aerial vehicle (UAV). The proposed concept is suitable to deliver parcels in high-density and high-rise urban or residential areas. In order to achieve the proposed concept, we will develop acooperative heterogeneous unmanned system. Customers can order goods using a smartphone application and the order information, including the position of the customer and the order time, and the package is transported automatically by the unmanned systems. The system assigns the tasks suitable for each unmanned vehicle by analyzing it based on map information. Performance is validated by experiments consisting of autonomous driving and flight tests in a real environment. For more evaluation, the landing position error analysis is performed using circular error probability (CEP).

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39B no.11
• /
• pp.771-778
• /
• 2014

We propose Femto-cell power control scheme in HeNet with Game Theory. The Femto-cell which provide high quality with low power is issued by many benefits, however there is a bunch of interferences when many Femto-cells use overlapped bandwidth with Macro-cell. We defined base station of cellular networks and mobile users as players of Game Theory, and configured interference effect among each other as power utility function. Futhermore, we showed enhanced overall system performance, lower power usage and interference decrease by using optimal power.