• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.242-247
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• 2009

In this paper, we investigate interference between short-range radiocommunication devices (SRDs) with frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS) methods when they are in the same frequency bands. In order to analyze interference from unwanted emission of SRD with DSSS to that of FHSS, Monte-Carlo (MC) simulation method is employed and interference probabilities are calculated. We simulate interference scenarios in accordance with several duty cycles and bandwidths. It is also assumed that the propagation model is free space The effect of distance between interfering transmitter and victim receiver is analyzed and bit error rate (BER) is simulated. From the interference analysis results, it is shown that duty cycle affects compatibility more than bandwidth does. Also, we can make sure of the separation distance which satisfies BER criterion when there are only one interfering transmitter and multiple interfering transmitters.

• Korean Journal of Human Ecology
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• v.9 no.2
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• pp.153-176
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• 2000

The purpose of this study is to compare the living cultures among three types of undergraduate students, grouped by commuting patterns, attending universities in Chung-Cheong Do: a long-distance type, a short-distance type, and a living-alone type. The survey was performed with questionnaires and the subjects were 1167 undergraduate students. The results are as follows: for a long-distance type, the levels of housing environments and consumption expenditures were relatively high, but the students felt constrainted by the commuting time. For a short-distance type, the consensus in decision-making with parents and the degree of conflict reconciliation were the lowest. For a living-alone type, the levels of housing environments and consumption expenditures were relatively poorer, but the students spent relative]y more time at school and the attitudes of school and department which they belong to were relatively higher.

• Earthquakes and Structures
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• v.25 no.2
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• pp.135-148
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• 2023

The structure-soil-structure interaction (SSSI) effect in adjacent structures may affect the liquefaction-induced damage of shallow foundation structures. The existing studies only analysed the independent effects on the structural dynamic response but ignored the coupling effect of height difference and distance of adjacent structures (F) on liquefied foundations on the dynamic response. Therefore, this paper adopts finite element and finite difference coupled dynamic analysis method to discuss the effect of the F on the seismic response of shallow foundation structures. The results show that the effect of the short structure on the acceleration response of the tall structure can be neglected as F increases when the height difference reaches 2 times the height of the short structure. The beneficial effect of SSSI on short structures is weakened under strong seismic excitations, and the effect of the increase of F on the settlement ratio gradually decreases, which causes a larger rotation hazard. When the distance is smaller than the foundation width, the short structure will exceed the rotation critical value and cause structural damage. When the distance is larger than the foundation width, the rotation angle is within the safe range (0.02 rad).

• Korean Journal of Poultry Science
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• v.36 no.1
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• pp.9-14
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• 2009

This study was conducted to evaluate the effect of three types of transportation distance (short: less than 40 km; intermediate: 70~80 km; long: 140~150 km) on quality of whole chicken and chicken meat cuts. In whole chicken, $1^+$ grade chicken incidence after transportation of short, intermediate, and long distance transportation was 61.3, 56.3, and 43.8%, respectively. Bruise was not shown in breast and thigh, while wings with bruise after short and long distance transportation were 16.7% and 27.3%, respectively. For chicken meat cuts, $1^+$ grade chicken breast incidence after short distance transportation was 14% higher than that after long distance transportation. Bruised chicken breast after short and long distance transportation were 10 and 12%. Pale, soft, and exudative (PSE) chicken breast incidence after long distance transportation was higher (18.3%) than that after short distance transportation (7.0%). Chicken thigh cuts with $1^+$ grade after short and long distance transportation were shown 91.2% and 88.3%, respectively. Also, chicken wing cuts showed similar result to chicken thigh cuts' and $1^+$ grade incidence of chicken wings after short distance transportation was 11% higher than that of after long distance transportation. These results suggest that shorter transportation distance from farm to slaughter house result in high grade whole chicken and chicken meat cuts.

• MALSORI
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• no.56
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• pp.195-206
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• 2005

Discrimination between speech and music is important in many multimedia applications. In this paper, focusing on the spectral change characteristics of speech and music, we propose a new method of speech/music discrimination based on cepstral distance. Instead of using cepstral distance between the frames with fixed interval, the minimum of cepstral distances among neighbor frames is employed to increase discriminability between fast changing music and speech. And, to prevent misclassification of speech segments including short pause into music, short pause segments are excluded from computing cepstral distance. The experimental results show that proposed method yields the error rate reduction of$68\%$, in comparison with the conventional approach using cepstral distance.

• The KIPS Transactions:PartC
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• v.10C no.3
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• pp.335-344
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• 2003

In accordance with the changes in the wireless communication environment, there has been a great need to satisfy the demand for diverse modes of information exchange. Various types of short-distance wireless communication technology have been developed and studied to meet this demand. Among them, Bluetooth and WLAN which has recently been acclaimed as the standard for short-distance wireless communication, has been the focus of many such studies. However, Bluetooth and WLAN has weaknesses in its security features when its in real services are applied to m-commerce. The purpose of this study is to propose techniques that affinity considers to item that is non-security enemy who is although there is no public secure division direct connection in peculiar environment of radio environment as well as limitation security enemy of short distance radio communication. Propose secure monitoring techniques for straggling device to user center also applying proposed way to Bluetooth and WLAN that are short distance communication representative technology based on item that is security enemy and item that is rain suity enemy.

• Journal of Korea Multimedia Society
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• v.7 no.11
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• pp.1610-1619
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• 2004

While researches and studies on short distance wireless communications have been actively carried out, studies on many applications of short distance wireless communications focusing on user-oriented Mobile device are also in progress. Since Bluetooth has several advantages that existing short distance communication does not have, studies on standardization have been carried out focusing on SIG, and IEEE has also jointly studied on this. Bluetooth is a short distance wireless communication technology that can be usefully applied to various kinds of applications. In this regard, this thesis presents payment system using Bluetooth, out of several application technologies of Bluetooth. This payment system is based on the scenario in which secure piconet is formed focusing on the user, the user gets in the car, fill up the gas at the gas station using his own Mobile device and pay The secure payment system presented in this thesis is designed to complement the weakness of existing Bluetooth in terms of security and to secure several requirements of security required for payment using short distance wireless communication.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.3
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• pp.299-309
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• 2016

This study proposed a logistics plan for sending supply to be distributed to areas other than producing areas to wholesalers and allocating supply to be distributed to areas near producing areas to local distribution center in the vicinity instead of shipping the entire quantity to wholesalers for fruits auction to increase the competitive edge of the domestic fruits and vegetables logistics market in the ear of infinite competition. A video auction-based short distance division logistics operation model was developed to enhance competitiveness related to the circulation of fruits and vegetables, reduce logistics costs, and rationalize logistics by distributing the items sent to wholesalers through field auction and the shipments at local distribution center to neighboring areas through video auction connected to wholesalers real-time. The study especially came up with a logistics rationalization plan by examining and analyzing the stages and costs of transportation between producing areas and wholesalers on the circulation routes of fruits.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.3
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• pp.157-167
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• 2011

Although vehicles become more intelligent for convenience and safety of drivers, traffic accidents are increased more and more. Especially, car-to-car single rear impacts in the urban area are increased rapidly because of driver inattention. To prevent rear impacts in the urban area, commercial automobile vendor applies the low-speed short-distance collision warning system. This paper presents low-speed short-distance collision warning algorithm for the city driving by using sensor fusion of laser sensor and ultrasonic sensor. An experiment using embedded microprocessor in the driving track was used to demonstrate the feasibility of the collision warning algorithm.

• Geomechanics and Engineering
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• v.37 no.4
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• pp.395-418
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• 2024

The epicentral region of earthquakes is typically where liquefaction-related damage takes place. To determine the maximum distance, such as maximum epicentral distance (R_e), maximum fault distance (R_f), or maximum hypocentral distance (R_h), at which an earthquake can inflict damage, given its magnitude, this study, using a recently updated global liquefaction database, multiple ML models are built to predict the limiting distances (R_e, R_f, or R_h) required for an earthquake of a given magnitude to cause damage. Four machine learning models LSTM (Long Short-Term Memory), BiLSTM (Bidirectional Long Short-Term Memory), CNN (Convolutional Neural Network), and XGB (Extreme Gradient Boosting) are developed using the Python programming language. All four proposed ML models performed better than empirical models for limiting distance assessment. Among these models, the XGB model outperformed all the models. In order to determine how well the suggested models can predict limiting distances, a number of statistical parameters have been studied. To compare the accuracy of the proposed models, rank analysis, error matrix, and Taylor diagram have been developed. The ML models proposed in this paper are more robust than other current models and may be used to assess the minimal energy of a liquefaction disaster caused by an earthquake or to estimate the maximum distance of a liquefied site provided an earthquake in rapid disaster mapping.