• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.11a
• /
• pp.339-342
• /
• 2010

Doosan Heavy Industries & Construction Co., Ltd. constructed a gas turbine engine test cell to verify operating characteristics and design parameters of 5MW class gas turbine engine for power generation under developing. Engine test cell was designed to satisfy critical requirements to scrutinize all performance parameters of the engine with safe and reliability in accordance with design specification. As the test cell developed can effectively reproduce engine operation conditions covering from start-up to maximum power condition, it can be utilized to make a continuing design improvement of the engine based on practical test data at full stretch. Moreover, it is expected to be serviceable to develop derivative engines and be utilized to put them into serial production and contribute to a competitiveness reenforcement as a gas turbine engine manufacturer.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.27 no.2
• /
• pp.204-212
• /
• 2017

The rotor dynamics and balancing technic for rotating equipment during engineering and manufacture stage are to be carefully considered in order to minimize the operation troubles regarding vibration during commissioning stage. In this paper, the test rig, which includes the disks as balancing plane, is designed and manufactured, so that the characteristic of rotor dynamics can be analyzed such as critical speed and mode shape. The critical speed predicted through natural frequency analysis is verified by the actual measurement on bearing housing vibration during start-up condition of test rig. The low speed balancing and the operating speed balancing test are performed respectively with consideration of first critical speed, and the residual unbalance amounts are estimated in accordance with the relevant method described in API standard. In addition, the single and dual plane balancing are carried out on main disk and trim disk depended on phase information at each balancing step.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.2 no.3
• /
• pp.175-180
• /
• 2004

In order to vitrify the combustible dry active waste (DAW) generated from Korean Nuclear Power Plants, a glass formulation development based on waste composition was performed. A borosilicate glass, DG-2, was formulated to vitrify the DAW in an induction cold crucible melter (CCM). The processability, product performance, and volume reduction effect of the candidate glass were evaluated using a computer code and were measured experimentally in the laboratory and CCM. The glass viscosity and electrical conductivity as the process parameters were in the desired ranges. Start-up and maintaining glass melt of the candidate glass were favorable in the CCM. The product of the glass product such as chemical durability, phase stability, and density was satisfactory. The vitrification process using the candidate glass was also evaluated assuming that it was operated as economically as possible.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.8S
• /
• pp.2679-2687
• /
• 2000

위성 ATM 망에서 TCP/IP 기반의 응용 서비스를 제공하기 위해서는 위성의 긴 전송지연과 이성 채널의 버스트 오류 특성에 따른 정확한 전송 성능의 영향과 분석이 요구되며, 아울러 성능 목표치가 제시되어야 한다. 본 논문은 2Mbps급 KOREASAT위성을 이용한 위성망과 지상망이 상호 연동된 실제 위성/지상 ATM LANE(LAN Emulation)을 구현하고, 위성 채널의 Eb/No와 TCP 소켓 버퍼 크기, 그리고 전송 메시지 크기를 바꾸어 가면서 그때의 TCP/IP 트래픽과 FTP의 전송성능을 비교 분석하였다. 아울러 IPoA(IP over ATM)기반의 영상회의 서비스에 대한 전송 품질 및 메시지 전달 특성 등을 분석하였다. 연구결과 TCP 소켓 버퍼 크기가 증가할 때 TCP의 전체 성능이 증가함을 알 수 있으나 제한된 최대 윈도우 크기 64kbytes와 위성채널의 오류 특성으로 인해 실제 최대 전송속도는 이론상의 목표치를 달성하지 못함을 보여 주었다. 또한 2Mbps 위성링크에서 Eb/No가 6dB 이하에서는 실제적으로 제공할 수 있는 최대 전송성능의 50%이하로 떨어져 TCP/IP over ATM 서비스가 거의 불가능함을 보여주었다. FTP의 경우, 파일 크기가 작으면 최대 전송속도에 도달하기 전에 파일 전송이 완료되어 대역폭 이용의 효율성 측면에서 TCP/IP의 slow start 메케니즘이 적절하지 않음을 보여주었다. 이울러 IPoA영상회의 서비스에서도 Eb/No가 약 6.5dB 이하에서는 영상이 거의 정지되고, 메시지 전달시간도 ITU에서 권고하는 목표치를 훨씬 상회하여 서비스가 거의 불가능함을 보였다.

• Journal of Korean Medicine Rehabilitation
• /
• v.29 no.3
• /
• pp.87-101
• /
• 2019

Objectives The purpose of this study is to investigate characteristics of low back pain patients and trends of Korean medicine conservative treatment effects of low back pain patients by registry data. Methods A total of 78 patients were analyzed, statistical analysis was performed using a generalized linear model. The comparison between groups was performed using independent two samples t-test or Wilcoxon rank sum test according to the distribution of normality. Before and after the treatment effects, ANOVA and Kruskal-Wallis method were used for the comparison, Sheffe method was used for the post test. Results The average age of hospitalized patients was 31.8 years old and out-patient department (OPD) patients was 44.9 years old. Lots of OPD patients and hospitalized patients were classified to 'Lumbago due to Coexist Qu Stagnation and Bloos Stasis'. Both OPD patients and hospitalized patients classified to 'Lumbago due to Coexist Qu Stagnation and Bloos Stasis' showed statistically significant decrease in RMDQ (Roland-Morris disability questionnaire) and NRS (numeric rating scale) on 1 month and 3 month after clinical research start date. Comparing the treatment effects of Chuna manual therapy, both Chuna group and non-Chuna group showed statistically significant decrease in RMDQ and NRS on discharge date, 1 month and 3 month after clinical research start date. Conclusions We expect that a larger scale registry study will be carried out to provide a higher level of basis for the Korean medical treatment of low back pain.

• Journal of the Korea Society of Computer and Information
• /
• v.25 no.12
• /
• pp.305-313
• /
• 2020

In this paper, We Propose a ways how franchise service of delivery app should be made by analyzing the effect of delivery app usage properties of food service franchisee on satisfaction, business performance and intention of reusing, and suggest support plan of delivery app for franchise by food service franchisee. This study conducted survey on 212 franchises that have experience using delivery app among food service franchisees. To verify the hypothesis of the study, single regression and multiple regression analysis were conducted for verifying the relationship between variables. Key results of the study are as follows. First, it was found that the delivery app usage properties of food service franchisee had a positive relationship with satisfaction. Second, it was found that the delivery app usage properties of food service franchisee had positive relationship with business performance. Third, the satisfaction was found to affect business performance. Fourth, it was found that the satisfaction didn't affect the intention of reusing, and business performance was found to have a positive effect on the intention of reusing. It is necessary to increase the satisfaction of using of franchises through continuous management and reasonable pricing policies, and the headquarter of franchisee should be able to contribute to energetic sales of franchises through effective cooperation with delivery app companies.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.7
• /
• pp.1657-1670
• /
• 2013

The increase in the number of music files in smart phone and MP3 player makes it difficult to find the music files which people want. So, Query-by-Singing/Humming (QbSH) systems have been developed to retrieve music from a user's humming or singing without having to know detailed information about the title or singer of song. Most previous researches on QbSH have been conducted using musical instrument digital interface (MIDI) files as reference songs. However, the production of MIDI files is a time-consuming process. In addition, more and more music files are newly published with the development of music market. Consequently, the method of using the more common MPEG-1 audio layer 3 (MP3) files for reference songs is considered as an alternative. However, there is little previous research on QbSH with MP3 files because an MP3 file has a different waveform due to background music and multiple (polyphonic) melodies compared to the humming/singing query. To overcome these problems, we propose a new QbSH method using MP3 files on mobile device. This research is novel in four ways. First, this is the first research on QbSH using MP3 files as reference songs. Second, the start and end positions on the MP3 file to be matched are estimated by using multi-layered perceptron (MLP) prior to performing the matching with humming/singing query file. Third, for more accurate results, four MLPs are used, which produce the start and end positions for dynamic time warping (DTW) matching algorithm, and those for chroma-based DTW algorithm, respectively. Fourth, two matching scores by the DTW and chroma-based DTW algorithms are combined by using PRODUCT rule, through which a higher matching accuracy is obtained. Experimental results with AFA MP3 database show that the accuracy (Top 1 accuracy of 98%, with an MRR of 0.989) of the proposed method is much higher than that of other methods. We also showed the effectiveness of the proposed system on consumer mobile device.

• Journal of the Korea Society of Computer and Information
• /
• v.26 no.12
• /
• pp.273-281
• /
• 2021

In this paper, we propose a ways how YouTube Mukbang content attributes affect favorability, satisfaction, and brand selection, and suggest to use YouTube Mukbang contents, and to propose a strategic marketing plan using YouTube at the food franchise. This study conducted survey on 218 people who had watched chicken Mukbang among YouTube Mukbang contents. Through previous studies, YouTube content attributes were classified into informativity, entertainment, reliability, and attractiveness. To verify the hypothesis of the study, single regression and multiple regression analysis were conducted for verifying the relationship between variables. Key results of the study are as follows. First, it was found that YouTube Mukbang content attributes had a positive relationship with favorability. Second, it was found that YouTube Mukbang content attributes had a positive relationship with satisfaction. Third, it was found that favorability had an effect on satisfaction. Fourth, it was found that favorability influenced brand selection. Fifth, it was found that satisfaction did not affect brand selection. Based on these findings, a strategic approach will be needed to increase users' favorability by providing attractive and accurate information through YouTube Mukbang contents and to continuously improve brand choices through continuous favorability to revitalizing YouTube marketing at the food franchise.

• Korean Journal of Environment and Ecology
• /
• v.29 no.3
• /
• pp.344-352
• /
• 2015

This study aims to identify the difference in the starting time of the dawn chorus of different species of birds and related environmental conditions. For this study, the bird songs were recorded every 2 hours a day starting from 2 hours before sunrise for a whole spring season (from April to June, 2014) in Korea. The recorded sounds were analyzed to find the starting time of each species' song by sonogram pattern using a sound analyzing program (Adobe Audition CC). To analyze the relationship between the environmental conditions and the time of the birdsong of each species, we collected the data of environmental conditions: daily precipitation, Julian date, time of sunrise and moonrise, temperature data and twilight time from the Korea Meteorological Office. As a result of this study, it was found that there are several statistical correlation between the starting time of the birdsong and environmental conditions (every environmental condition except daily precipitation and time of moonrise). Also, the difference of the starting time among each species were identified. The species were divided into 3 groups (early, mid and late) by their wake-up time. Ring-necked pheasant and yellow-throated bunting were categorized as 'Early' group and all woodpeckers were categorized as'Late' group. This study is significant as it first presented a classification of wild birds in Korea by the starting time of their dawn chorus. However, further studies are required to identify why each species to do their dawn singing at different times.

• Korean Journal of Bronchoesophagology
• /
• v.15 no.2
• /
• pp.42-48
• /
• 2009

Background and Objectives : Obstructive laryngeal cancers have to be managed with tracheostomy, which has been reported with increased local or stomal recurrence. Stomal recurrence after treatment of laryngeal cancer is one of the most serious issues in the management of laryngeal cancer. Prognosis of locally advanced laryngeal cancer in patients with previous tracheostomy is evaluated. Materials and Methods : Between 1996 and 2007, 174 patients with previously untreated advanced laryngeal cancer(stage III, IV) were enrolled. Overall survival(OS) and disease specific survival(DSS) according to the presence of previous tracheostomy were compared. OS and DSS of the groups with different duration from tracheostomy to treatment were compared. Results : Among 174 patients with advanced laryngeal cancer, previous tracheostomy was performed in 24 patients. Of 24 patients, there were stomal recurrences in 5 patients. DSS of previous tracheostomy group and that of the other group were statistically different(p=0.001). There was statistical significant difference between OS of groups which start treatment more than 14 days after tracheostomy and within 14 days(p=0.03). Conclusions : If possible, Previous tracheostomy should be avoided and if it is inevitable, the elective treatment should be recommended at least within 2 weeks.