• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11A
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• pp.1827-1840
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• 2001

In digital data transmission/storage systems, the compensation for channel distortion is conducted normally using a training sequence that is known a priori to both the sender and receiver. The use of the training sequences results in inefficient utilization of channel bandwidth. Sometimes, it is also impossible to send training sequences such as in the burst-mode communication. As such, a great deal of attention has been given to the approach requiring no training sequences, which has been called the blind equalization technique. On the other hand, to utilize the limited bandwidth effectively, the concept of partial response (PR) signaling has widely been adopted in both the high-speed transmission and high-density recording/playback systems such as digital microwave, digital subscriber loops, hard disk drives, digital VCRs and digital versatile recordable disks and so on. This paper is concerned with blind adaptive equalization of partial response channels whose transfer function zeros are located on the unit circle, thereby causing some problems in performance. Specifically we study how the problems of blind channel equalization associated with the PR channels can be improved. In doing so, we first discuss the existing methods and then propose new structures for blind PR channel equalization. Our structures have been extensively tested by computer simulation and found out to be encouraging in performance. The results seem very promising as well in terms of the implementation complexity compared to the previous approach reported in literature.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.203-209
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• 2022

One of the typical methods for lowering radiation dose while maintaining image quality of computed tomography (CT) is the use of model-based iterative reconstruction (MBIR). This study is to evaluate the image quality by adjusting the strength of the advanced modeled iterative reconstruction (ADMIRE), which is well known as a representative model of MBIR. The study was conducted using phantom, and CT images were obtained while adjusting the strength of ADMIRE in units of 1 to 5. Quantitative evaluation includes noise levels using coefficient of variation (COV) and contrast to noise ratio (CNR), as well as natural image quality evaluation (NIQE) and blind/referenceless image spatial quality evaluator (BRISQUE). As a result, in both noise level and blind quality evaluation results, the higher the strength of ADMIRE, the better the results were derived. In particular, it was confirmed that COV and CNR were improved 1.89 and 1.75 times at ADMIRE 5 compared to ADMIRE 1, respectively, and NIQE and BRISQUE were proved to be improved 1.35 and 1.22 times at ADMIRE 5 compared to ADMIRE 1, respectively. In conclusion, this study was proved that the reconstruction strength of ADMIRE had a great influence on the noise level and overall image quality evaluation of CT images.

• Journal of Internet Computing and Services
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• v.24 no.6
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• pp.81-89
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• 2023

In modern society, blind people face difficulties in navigating common environments such as sidewalks, elevators, and crosswalks. Research has been conducted to alleviate these inconveniences for the visually impaired through the use of visual and audio aids. However, such research often encounters limitations when it comes to practical implementation due to the high cost of wearable devices, high-performance CCTV systems, and voice sensors. In this paper, we propose an artificial intelligence fusion algorithm that utilizes low-cost video sensors integrated into smartphones to help blind people safely navigate their surroundings during walking. The proposed algorithm combines motion capture and object detection algorithms to detect moving people and various obstacles encountered during walking. We employed the MediaPipe library for motion capture to model and detect surrounding pedestrians during motion. Additionally, we used object detection algorithms to model and detect various obstacles that can occur during walking on sidewalks. Through experimentation, we validated the performance of the artificial intelligence fusion algorithm, achieving accuracy of 0.92, precision of 0.91, recall of 0.99, and an F1 score of 0.95. This research can assist blind people in navigating through obstacles such as bollards, shared scooters, and vehicles encountered during walking, thereby enhancing their mobility and safety.

• Medical Lasers
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• v.9 no.2
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• pp.150-158
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• 2020

Background and Objectives Low-level laser therapy (LLLT) is used widely to promote hair growth in androgenetic alopecia (AGA). This study examined the clinical efficacy and safety of a home-use LLLT device with a newly designed array of light sources and software optimized for individual types of AGA. Materials and Methods The study was a randomized, double-blind, sham device-controlled trial. Forty-eight subjects (39 men and nine women) were assigned randomly in a 2:1 ratio to use either the test device (LG Pra'L HGN1, LG electronics, Korea) or sham device. The subjects used the LLLT device three times a week for 16 weeks. Phototrichogram was used to measure the hair density and hair thickness at 0, 8, and 16-weeks. Adverse events were closely monitored. Results After 16 weeks of using the device, the test group showed a significant increase in hair density and hair thickness compared to the control. In the test group, the hair density increased 6.96 counts/cm² at eight weeks and 13.67 counts/cm² at 16 weeks from the baseline. The hair thickness increased 7.21 ㎛ at eight weeks and 11.80 ㎛ at 16 weeks compared to the baseline. Conclusion The home-use LLLT device with a novel array of light sources and an individualized program according to the types of hair loss appears to be an effective and safe treatment modality for both male and female AGA patients.

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.6
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• pp.52-61
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• 2015

Personal distance is one of the basic and important concepts in the field of Environmental Psychology in influencing personal space, visible or invisible territoriality and psychological carrying capacity of contemporary urban dwellers. This study aims to analyze the bench users' behaviour and personal distances in urban parks for the first time in Korea, one of the representative landscape spaces in urban areas. For these purposes, this study has adopted a blind observation and pictorial analysis for bench users in Yeouido Park in Seoul. The main results of this study show that the average interpersonal distance between female and male(intimate relationship) is 47.5cm, the distance between female and female is 53.2cm, and the distance between male and male is 70.3cm. These results mostly support the previous western study results, but the interpersonal space and territoriality of Koreans in urban parks may be smaller than that for western societies.

• Convergence Security Journal
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• v.15 no.2
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• pp.11-17
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• 2015

According to NIA (National Information Society Agency) report, digital divide is a vicious circle which makes quality interval of human's life between people who have information and relatively not. Especially in a smart phone society, there is a big problem between disabled people and normal people. This paper suggests a braille keyboard system for the blind to solve these problems. It is designed for portable use, convenience and quick text typing based on bluetooth communication technique. In text input test, all texts (Korean, English, number) were accurately expressed and typing speed was about 22 [c/m](characters per a minute). Especially, we design text2voice function to provide more accurate key input system. Popular applications such as call, alarm, message, kakao talk, internet, music, were performed without carring problems using the proposed braille keyboard system. The proposed technique is thought to contribute to eliminating the digital divide through the expansion of smartphone users.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6A
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• pp.920-930
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• 1999

Many researches on the multi-level QAM(Quadrature Amplitude Modulation) which is known to be a promising digital data transmission method for efficient use of channel bandwidth have been carried on, and their applications to various real fields are now being in progress. However, in the band-limited communication systems, each transmitted symbols is distorted by the ISI(Intersymbol Interference) and the phase error. Therefore, an equalizer and a carrier recovery must be taken into considerations to attenuate the effects of these distortions in the receiver. This paper presents an effective receiver structures that is applicable to the multi-level QAM. The proposed receiver system is consisted of an equalizer with Godard’s blind algorithm and a carrier recovery circuit. The phase error is estimated with a $\theta$-matching algorithm and is used in the carrier recovery to recover the correct phase. The simulation results are included to evaluate performance of the proposed receiver system for the various channel models.

• Phonetics and Speech Sciences
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• v.5 no.4
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• pp.217-225
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• 2013

This paper describes the design and implementation of the kWebAnywhere system based on WebAnywhere, which assists people with severely diminished eye sight and the blind people to access Internet information through Web interfaces. The WebAnywhere is a server-based web reader which reads aloud the web contents using TTS(text-to-speech) technology on the Internet without installing any software on the client's system. The system can be used in general web browsers using a built-in audio function, for blind users who are unable to afford to use a screen reader and for web developers to design web accessibility. However, the WebAnywhere is limited to supporting only a single language and cannot be applied to Korean web contents directly. Thus, in this paper, we modified the WebAnywhere to serve multiple language contents written in both English and Korean texts. The modified WebAnywhere system is called kWebAnywhere to differentiate it with the original system. The kWebAnywhere system is modified to support the Korean TTS system, VoiceText$^{TM}$, and to include user interface to control the parameters of the TTS system. Because the VoiceText$^{TM}$ system does not support the Festival API used in the WebAnywhere, we developed the Festival Wrapper to transform the VoiceText$^{TM}$'s private APIs to the Festival APIs in order to communicate with the WebAnywhere engine. We expect that the developed system can help people with severely diminished eye sight and the blind people to access the internet contents easily.

• Steel and Composite Structures
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• v.20 no.5
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• pp.1067-1085
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• 2016

Recent research on steel moment-resisting connection between steel beams and concrete filled steel tubes has shown that there are considerable advantages to be obtained by anchoring the connection to the concrete infill within the tube using anchors in blind bolts. In the research reported here, extensive experimental tests and numerical analyses have been performed to study the anchorage behaviour of cogged deformed reinforcing bars within concrete filled circular steel tubes. This data in essential knowledge for the design of the steel connections that use anchored blind bolts, both for strength and stiffness. A series of pull-out tests were conducted using steel tubes with different diameter to thickness ratios under monotonic and cyclic loading. Both hoop strains and longitudinal strains in the tubes were measured together with applied load and slip. Various lead-in lengths before the bend and length of tailed extension after the bend were examined. These dimensions were limited by the dimensions of the steel tube and did not meet the requirements for "standard" cogs as specified in concrete standards such as AS 3600 and ACI 318. Nevertheless, all of the tested specimens failed by bar fracture outside the steel tubes. A comprehensive 3D Finite Element model was developed to simulate the pull-out tests. The FE model took into account material nonlinearities, deformations in reinforcing bars and interactions between different surfaces. The FE results were found to be in good agreement with experimental results. This model was then used to conduct parametric studies to investigate the influence of the confinement provided by the steel tube on the infilled concrete.

• The Journal of the Korea Contents Association
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• v.7 no.12
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• pp.254-261
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• 2007

In this paper, we propose a blind equalization method for advanced terrestrial digital multimedia broadcasting (AT-DMB) systems which use hierarchical modulation. The AT-DMB system adopts hierarchical 16-ary quadrature amplitude modulation (16-QAM) to ensure backward-compatibly with the differential quadrature phase shift keying (DQPSK) signal of the legacy terrestrial digital multimedia broadcasting (T-DMB) systems and to support higher transmission rate. Due to the hierarchical modulation, the conventional T-DMB signal and the additional signal have different error rate at same signal to noise ratio (SNR). By weighting the decided symbols differently according to the reliability of the symbols, i.e., high priority symbol with low error rate and low priority symbol with high error rate, we can improve the channel estimation accuracy. In this paper, we analyze SNR loss by hierarchical modulation and confirm it through simulations. Moreover, through simulations, we verify that the proposed weighting method improve BER compared to the no-weighting method.