• The Journal of the Acoustical Society of Korea
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• v.38 no.5
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• pp.494-510
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• 2019

Underwater acoustic communication channel parameters consist of impulse response, delay spreading, scattering function, coherence bandwidth, frequency selective fading, coherence time and time variant magnitude fading statistics on which communication system modem and channel coding are designed. These parameters are influenced by sound velocity profile, platform motion and sea surface roughness in given acoustical oceanography condition. In this paper, channel model based on phasor, channel simulator, measurement and analysis method of channel parameters are given in a fixed source-to-receiver system and the parameters are analyzed using shallow water experimental data. For two different source-to-receiver ranges of 300 m and 600 m, the parameters are characterized by three multipaths such as a direct, a surface reflection path with time variant scattering and a bottom reflection path. The results present a channel modelling method of a fixed source source-to-receiver system, channel parameters measurement and analysis methods and a system design and performance assessment method in shallow water.

• The Journal of Korean Medicine
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• v.40 no.2
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• pp.72-88
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• 2019

Objectives: The purpose of this study is to understand the experience of traffic accident patients with serious injury treated with Traditional Korean Medicine (TKM). Methods: This study was conducted on the basis of grounded theory. We recruited 10 participants who had been hospitalized in Dongguk University Bundang Oriental Hospital after traffic accident. Raw data was collected by in-depth interview, and analyzed by using constant comparison. The coding(open-axial-selective) was performed in order to create paradigm and theoretical model, which can explain main theme of this study. Results: Core phenomenon of this study was 'Experiencing TKM treatment as an alternative' and core category was 'Searching for the answer to the management of traffic accident sequela through TKM treatment' Conclusions: For patients with serious injury, 'Experiencing TKM treatment as an alternative' has meaning as the following: First, The absence of accurate radiography and surgical management makes it hard for patients to choose Korean medicine hospital immediately after traffic accident. Second, Effectiveness of TKM treatment should be evaluated in the long term. Third, TKM treatment is superior to Western medicine treatment in managing long-term patients who suffered from serious injury involved in traffic accident. Finally, Cooperative service of the Western medicine and TKM will provide more satisfactory medical care for traffic accident patients.

• Journal of Hospice and Palliative Care
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• v.23 no.4
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• pp.183-197
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• 2020

Purpose: In this study, the researchers closely investigated the psychosocial problems faced by terminal cancer patients and their family members in hospice palliative care units. Methods: The investigators conducted four sessions of art therapy intervention programs for the terminal cancer patients and their family members, carried out in-depth interviews about the influence of the cancer experience on their family function and quality of life, and analyzed their experiences using grounded theory methodology. Results: After providing autonomous written informed consent, six pairs of terminally ill cancer patients and their family members, accounting for a total of 17 participants with the inclusion of additional family members who took part sporadically, took part in the art therapy intervention and interviews. The raw data, in the form of verbatim records, were analyzed according to the procedures of grounded theory (open, axial, and selective coding). Through these processes, a total of 154 concepts, 56 subcategories, and 13 categories were identified. Families were classified into four types according to their family function, quality of life, and attitude toward death. Though the art therapy intervention, patients and their family members experienced three stages over time. Conclusion: This research focused on essential aspects of the family relationships and the art therapy experiences of terminal cancer patients and their family members through an art therapy intervention in the context of hospice palliative care. Based on these observations, the researchers constructed a theoretical rationale for art therapy interventions delivered to patients and their family members in the process of hospice palliative care.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.35 no.4
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• pp.1-30
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• 2022

Objectives : The purpose of this study was to explore the experience of patients with facial palsy symptoms treated with Korean medicine treatment(KMT) after western treatment. Methods : We conducted an individual in-depth interview with 10 participants who had experience in both western and KMT for facial palsy symptoms. This qualitative study adopted the grounded theory of Strauss and Corbin, and collected data was analyzed by using coding(open-axial-selective) that was performed to create paradigm model, which can explain this study's main theme. Results : The central phenomenon of this study was 'choosing Korean medicine treatment after western treatment preceded', and the core category was derived as 'selecting process of KMT after western medical treatment and improvement plan of Korean medicine treatment'. Conclusions : For patients with facial palsy, KMT was perceived as an essential treatment rather than an alternative, and recognized as the main treatment. Patients didn't settle for western treatment which was in progress, actively selected KMT and suggested the specific plan for improvement of KMT. Through this, we should be considered the direction of the KMT for facial palsy symptom which is the common disease of KMT.

• Journal of Broadcast Engineering
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• v.28 no.2
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• pp.194-212
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• 2023

The MPEG immersive video (MIV) coding standard achieved high compression efficiency by removing inter-view redundancy and merging the residuals of immersive video which consists of multiple texture (color) and geometry (depth) pairs. Grouping of views that represent similar spaces enables quality improvement and implementation of selective streaming, but this has not been actively discussed recently. This paper introduces an implementation of group-based encoding into the recent version of MIV reference software, provides experimental results on optimal views and videos per group, and proposes a decision method for optimal number of videos for global immersive video representation by using portion of residual videos.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.18 no.1
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• pp.67-83
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• 2023

The social venture start-up phenomenon is found from the perspectives of social enterprise and for-profit enterprise. This study aims to fundamentally explore the start-up phenomenon of social ventures from these two perspectives. Considering the lack of prior research that researched both social and commercial perspectives at the same time, this paper analyzed using grounded theory approach of Strauss & Corbin(1998), an inductive research method that analyzes based on prior research and interview data. In order to collect data for this study, eight corporate representatives currently operating social ventures were interviewed and data and phenomena were analyzed. This progressed to a theoretical saturation where no additional information was derived. The analysis results of this study using the grounded theory approach are as follows. As a result of open coding and axial coding, 147 concepts and 70 subcategories were derived, and 18 categories were derived through the final abstraction process. In the selective coding, 'expansion of social venture entry in the social domain' and 'expansion of social function of for-profit companies' were selected as key categories, and a story line was formed around this. In this study, we saw that it is necessary to conduct academic research and analysis on the competitive factors required for companies that pursue the values of two conflicting relationships, such as social ventures, to survive with competitiveness. In practice, concepts such as collaboration with for-profit companies, value combination, entrepreneurship competency and performance improvement, social value execution competency reinforcement, communication strategy, for-profit enterprise value investment, and entrepreneur management competency were derived. This study explains the social venture phenomenon for social enterprises, commercial enterprises, and entrepreneurs who want to enter the social venture field. It is expected to provide the implications necessary for successful social venture startups.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.12
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• pp.2394-2402
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• 2017

The frequency selective fading by multipaths determines a performance of underwater acoustic communication system in shallow littoral ocean. In this study, a characteristics of underwater acoustic channel and performance of multi-carrier system is evaluated in littoral ocean with a 50m deep water, an effective wave height of 0.5m and sandy mud bottom near Busan city. A multipath delay spread and time and frequency domain are presented as a function of a transmitter-to-receiver range. A bit-error-rate of a 5 channel 4FSK(Frequency Shift Keying) with a transmission rate of 1kbps, is examined and RS(Reed-Solomon) code is also adopted to remove a burst error due to time domain fading. A number of multipath are less than four and a bit-error-rate is decreased as an increase of a transmitter-to-receiver range which gives a congestion of multi-paths resulting in a decrease of time and frequency domain fading. The measured bit-error-rate is about 10-4 at greater than 600m of transmitter-to-receiver range.

• The Journal of the Acoustical Society of Korea
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• v.32 no.6
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• pp.494-501
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• 2013

The convolution code(CC) of code rate 1/2 as a forward error correction (FEC) in Quadrature Phase Shift Keying (QPSK) is applied to decrease bit error rate (BER) by background noise and multipath in shallow water acoustic channel. Ratio of transmitting signal bandwidth to channel coherence bandwidth is defined as frequency selectivity index. BER and bit energy-to-noise ratio gain of transmitted signal according to frequency selectivity index are evaluated. In the results of indoor water tank experiment, BER is well matched theoretical results at frequency selectivity index less than about 1.0. And bit energy-to-noise ratio gain is also matched theoretical value of 5 dB. BER is effectively decreased at frequency selective multipath channel with frequency selectivity index higher than 1.0. But bit energy-to-noise ratio greater than a certain size in terms of CC weaving is effective in reducing bit errors. In the results, the defined frequency selectivity index in this study could be applied to evaluate a performance of CC in multipath channel. Also it could effectively reduced BER in a low speed underwater acoustic communication system without an equalizer.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1239-1247
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• 2003

OFDM(orthogonal frequency division multiplexing) communications system is very attractive for the high data rate transmission in the frequency selective lading channel. Since OFDM has high PAPR(peak-to-average power ratio), OFDM signal may be distorted by the nonlinear HPA(high power amplifier). In this paper, we propose the DSI(dummy sequence insertion) method for OFDM communication system. Some sub-carriers are inserted for PAPR reduction. They carry the specified dummy data sequence which are used for only PAPR reduction and do not work as side information like the conventional PTS(partial transmit sequence) or SLM(selected mapping) method. We use the complementary sequence and the combination of the correlation sequence as the dummy sequence. Flipping technique is used for the DSI method to get the effective PAPR reduction. It is important that BER of the proposed method is independent of the damage of the dummy data sequence. And DSI method has better spectral efficiency than the conventional block coding. On the other hand, threshold PAPR method is applied to cut down the processing time. However, this DSI method is not better than the conventional PTS method in the respect of the PAPR reduction performance. The DSI method includes the threshold PAPR lower than the PAPR of the OFDM signal, reduces the processing time and improves the BER performance.