• Electronics and Telecommunications Trends
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• v.33 no.2
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• pp.39-47
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• 2018

The fundamental problem of communication is that of transmitting a message from a source to a destination over a channel through the use of a transmitter and receiver. To derive a theoretically optimal solution, the transmitter and receiver can be divided into several processing blocks, with each component analyzed and optimized. The idea of machine learning (or deep learning) communications systems goes back to the original definition of the communi-cation problem, and optimizes the transmitter and receiver jointly. Although today's systems have been optimized over the last decades, and it seems difficult to compete with their performance, deep learning based communication is attractive owing to its simplicity and the fact that it can learn to communicate over any type of channel without the need for mathematical modeling or analysis.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.140-145
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• 2008

Recently more complex geometric shapes, including freeform surfaces, are adopted for the design of products to emphasize style or beauty. Modeling of these products is extremely difficult or often impossible. Reverse engineering is the latest technology that can solve the problem by generating CAD models from the physical mockups or prototype models. Reverse engineering uses the coordinate measuring machine(CMM) to get the shape data of products. CMM is limited by the size of the product; therefore it must need the feature to solve it. The tooling-ball which is generally used for feature has difficulty in being used for soft products. Besides, the higher the accuracy of the tooling-ball is, the more expensive its cost is. This study will develop the feature of high accuracy without additional tools and compare the difference of accuracy by it.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.7
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• pp.581-601
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• 1990

A variety of method to diagnose the fault of rotational mechine is suggested, the latest data. This paper uses Bispectrum which is sort of high order spectrum, diagnose the ball bearing of the rotational machine element. Apprehending the physical meaning of Bispectrum, computer simulation is performed. The result from computer simulation and the signal of the faulted ball bearing is studied from all it's aspects. It is found that the Bispectrum is more effective than the conventional Power Spectrum.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.519-523
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• 2003

This paper describes the communication system of sequencing sorter. Generally sequencing sorter is a machine that sorts mails by delivery order. And designed sequencing sorter is composed of 5 physical modules. So, it is necessary to communicate with each module and to control this communication. A computer called Machine Management Computer, controls this. This paper is about the communication system with MMC and module controllers. This is PC-based, asynchronous full-duplex 4-wire serial systems. 3 protocol layers are presented and stop-and-wait flow control is adopted. Because designed sequencing sorter has to be operated high speed about 27,000 letters per hour, we analyzed the network traffic in the worst case. So, we could find that the communication system has to use above 115,200bps speed.

• Tunnel and Underground Space
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• v.4 no.2
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• pp.144-155
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• 1994

This research is designed to assess current achievement levels for mechanized excavation systems in Korea adn suggest the model predictive of TBM performance using statistical approaches. A test section in the TBM construction sites is selected to measure and analyze TBM performance. The field records including operating data, time allocation into downtime catagories, and machine design are analyzed on a shift basis. There are a total of 240 shifts, with most days operating two shifts per day. Examples of the probability density functions produced from the test section are presented and discussed. Relationships between TBM penetration rate and rock physical properties are investigated and the empirical equations for TBM performance prediction are also assessed with the field data.

• Annual Conference of KIPS
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• 2013.11a
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• pp.192-194
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• 2013

가상화 기술의 발달은 클라우드 데이터센터(cloud datacenter)에서의 서버 통합(server consolidation)을 지원하며 이를 통하여 물리적 머신(physical machine, PM) 관리 비용을 감소시킬 수 있다. 그러나 서버가 통합됨에 따라 가상 머신(virtual machine, VM) 간섭이 생길 수 있고 이는 성능 감소의 원인이 된다. 따라서 VM 간섭과 PM 관리 비용을 감소시키는 것은 트레이드오프(trade-off)를 이루며 본 논문에서는 이를 해결하기 위하여 VM 간섭 계측(quantizing)을 위한 기법과 비용 효율적 VM 배치(placement)를 위한 휴리스틱(heuristics)을 제안한다.

• Structural Engineering and Mechanics
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• v.92 no.1
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• pp.65-79
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• 2024

This work aims to present an analysis of the structural reliability of reinforced concrete (RC) columns designed according to the general method outlined in Eurocode 2 (EN 1992-1-1 2004). Probabilistic analyses are conducted by integrating the Monte Carlo method with metamodels (or surrogate models) generated using Kriging and some machine learning techniques. The study was developed based on an algorithm that verifies the columns subject to biaxial bending, considering the physical and geometric nonlinearities. Columns were analyzed assuming sign inversion of end bending moments (with reverse curvature), which portray the typical situations in conventional structures of RC buildings. The probabilistic results reveal that the typical RC columns in buildings designed according to the design procedures of the studied standard, whether they are located at the center, corner, or edge, exhibit reliability levels surpassing those deemed acceptable within the technical community. Furthermore, the integration of surrogate models proves beneficial by alleviating the computational burden associated with evaluations while preserving accuracy.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.22 no.2
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• pp.57-63
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• 2016

Background: Instability due to ankle sprains will be accompanied by a problem of balance and pain change. Balance trainer is used to improve the ankle strength and balance ability. The purpose of this study was to evaluate the change of pain and postural balance ability in ankle joint after balance trainer application in patients with ankle sprain and instability. Methods: Twenty patients in K hospital in Incheon were enrolled. Balance trainer was applied to 10 subjects in the experimental group and 10 subjects in the Balance cushion under the same conditions as the experimental group to compare the pain and balance ability. Results: In the experimental group, there was a significant difference in the change of the pain variation. In the postural balance ability comparison, there was a significant difference in total and post - posterior comparison compared to the control, but there was no significant difference in the postural balance ability comparison. Conclusion: Pain and postural balance ability of patients with instability due to ankle sprain improved the pain and balance ability of the Balance trainer group compared to the Balance cushion training group.

• Physical Therapy Korea
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• v.30 no.2
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• pp.102-109
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• 2023

Background: While efforts have been made to differentiate fall risk in older adults using wearable devices and clinical methodologies, technologies are still infancy. We applied a decision tree (DT) algorithm using inertial measurement unit (IMU) sensor data and clinical measurements to generate high performance classification models of fall risk of older adults. Objects: This study aims to develop a classification model of fall risk using IMU data and clinical measurements in older adults. Methods: Twenty-six older adults were assessed and categorized into high and low fall risk groups. IMU sensor data were obtained while walking from each group, and features were extracted to be used for a DT algorithm with the Gini index (DT1) and the Entropy index (DT2), which generated classification models to differentiate high and low fall risk groups. Model's performance was compared and presented with accuracy, sensitivity, and specificity. Results: Accuracy, sensitivity and specificity were 77.8%, 80.0%, and 66.7%, respectively, for DT1; and 72.2%, 91.7%, and 33.3%, respectively, for DT2. Conclusion: Our results suggest that the fall risk classification using IMU sensor data obtained during gait has potentials to be developed for practical use. Different machine learning techniques involving larger data set should be warranted for future research and development.

• Journal of Korean Academy of Nursing
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• v.27 no.3
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• pp.577-587
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• 1997

Purpose : To collect and interpret basic data involving the discomfort level of platelet donors and to see which nursing interventions would help make plateletpheresis more comfortable. Methods : Using "the Platelet Donor's Discomfort Scale" developed by the researcher herself and reviewed by an expert panel, the severity of discomfort as well as factors contributing to the development of this discomfort were analyzed. This scale contained 59 items and each item was scored by the 4-point Likert manner. Between March 1, 1996 and May 31, 1996, 500 platelet donors(16 years of age and older) were enrolled in this study. The Statistical methods used were factor analysis, t-test, and ANOVA. The results were as follows : 1. The mean of the platelet donor's discomfort scale was 130, range 69-207, possible score ranging from 59-236. 2. The platelet donor's discomfort scale had psychological, environmental, physical, and time-related factors. The time- related factor was the highest positive correlation with the development of the discomfort. 3. In looking at the psychological and environmental factors of the discomfort scores, the 16-20 age group had significantly higher ratings than those of the 26-30 age group. The students' group had higher scores than the soldier's group, and those who used the V-50, MCS -3P, or the PCS Plus machines had higher scores than those who used the COBE Spectra machine(P<.05, respectively), 4. In relation to the physical factor of the discomfort score, the youngest group felt significantly more discomfort, the student's group had a higher score than the soldier's group, and those who used the V-50, MCS-3P, or or the PCS Plus machines had higher scores than those who used the COBE Spectra machine(P<.05, respectively). 5. The time related factor of the discomfort score had the highest scores in every variable, however, statistically significant differences were not found between any of the variables(P>.05). Conclusion : Based on the above results, it can be oserved that the time-related factor was the most important factor influencing discomfort. The age and job of the donor, as well as the type of machine used, were significant variables in predicting the level of discomfort, regardless of psychological, environmental, and physical factors. This data could be used to determine nursing interventions that would relieve some of the discomfort of patients, as well as donors, undergoing plateletpheresis. Furthermore, consideration of the donor's time, introduction of a platelet donor pool system, publicity and education about platelet donation are required.