• 대기
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• 제31권5호
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• pp.489-510
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• 2021

In this paper, we propose an algorithm for detecting convective initiation (CI) using GEO-KOMPSAT-2A/advanced meteorological imager data. The algorithm identifies clouds that are likely to grow into convective clouds with radar reflectivity greater than 35 dBZ within the next two hours. This algorithm is developed using statistical and qualitative analysis of cloud characteristics, such as atmospheric instability, cloud top height, and phase, for convective clouds that occurred on the Korean Peninsula from June to September 2019. The CI algorithm consists of four steps: 1) convective cloud mask, 2) cloud object clustering and tracking, 3) interest field tests, and 4) post-processing tests to remove non-convective objects. Validation, performed using 14 CI events that occurred in the summer of 2020 in Korean Peninsula, shows a total probability of detection of 0.89, false-alarm ratio of 0.46, and mean lead-time of 39 minutes. This algorithm can be useful warnings of rapidly developing convective clouds in future by providing information about CI that is otherwise difficult to predict from radar or a numerical prediction model. This CI information will be provided in short-term forecasts to help predict severe weather events such as localized torrential rainfall and hail.

• 대한조선학회논문집
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• 제59권3호
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• pp.183-191
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• 2022

A design method for a propeller type rim-driven axial-flow turbine for a micro-hydropower system is presented. The turbine consists of pre-stator, impeller and post-stator, where the pre-stator plays a role as a guide vane to provide circumferential velocity to the on-coming flow, and the impeller as a rotational power generator by absorbing angular momentum of the flow. BEM(Blade Element Method), which is based on the turbine Euler equation, is employed to design the pre-stator and impeller blades. NACA 66 thickness form and a=0.8 mean camber line, which is widely accepted as a marine propeller blade section, is used for the pre-stator and turbine blade section. A CFD method, derived from the discretization of the RANS equations, is applied for the analysis of the designed turbine system. The design conditions of the turbine is confirmed by the CFD calculation. Turbine characteristic curve is calculated by the CFD method, in order to provide the performance characteristics at off-design operation conditions. The proposed procedures for the design of a propeller type rim-driven axial-flow turbine are established and confirmed by the CFD analysis.

• 한국인터넷방송통신학회논문지
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• 제22권6호
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• pp.83-89
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• 2022

최근 정보통신기술의 발전에 따라 사물인터넷 기술이 비약적으로 발전하고 있다. IoT 기술은 다양한 센서들을 활용하여 각 센서의 고유한 데이터를 발생시켜 시스템 상태의 진단을 가능하도록 한다. 하지만, 현재 적용되고 있는 장비운용 시스템은 장비에 문제가 발생한 후 관리자가 해당 문제를 처리해야하는 사후보전 방식의 개념이며, 이는 시스템의 에러로 인한 시스템의 신뢰성 및 가용성 문제점을 의미할 수 있으며, 정비를 위한 시스템 중단으로 생산성에 부정적 영향으로 인한 경제적 손실을 초래할 수 있다. 따라서, 본 연구에서는 지능형 IoT(AIoT) 기술을 적용하여 공장 내 정류기를 보다 효율적으로 운용하기 위한 엣지 컨트롤러 제어 의사 결정 알고리즘과, 정류기 부품별 고장 상황 정보에 대한 도메인 지식 기반의 모델링을 작성하여, 이를 바탕으로 수집된 각 센서 데이터에 대한 상관관계 분석을 통해 시나리오별 Abnormal 데이터에 대하여 적정 수준의 상태 메시지를 출력함을 확인할 수 있었으며, 이를 통한 기존 현장의 장비 운용 시스템의 가용성과 생산성이 향상됨을 확인하였다.

• 대한통합의학회지
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• 제10권2호
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• pp.145-153
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• 2022

Purpose : This study aimed to investigate the effects of blended learning on learning satisfaction in nursing students. Methods : This study was conducted with 160 current nursing students in the department of nursing at K university located in city B. All students included in the study understood the purpose of the study and provided informed consent to participate. Data were collected between May 3 and July 9, 2021 and analyzed using SPSS/WIN 22.0. The frequency, percentage, mean, and standard deviation were created, and t-test, ANOVA, and Scheffé test for post hoc analysis were performed. Correlations were analyzed using Pearson's correlation coefficient. The factors influencing learning satisfaction were analyzed using multiple regression. Results : Significant differences were observed for academic stress according to the online classes environmental satisfaction (F=4.10, p=.001), online classes experience (t=4.11, p=.001) and self-directed learning ability according to the grade (F=4.10, p=.001), online classes environmental satisfaction (t=4.11, p=.001). The academic stress of nursing students who experienced blended learning was significantly negatively correlated with self-directed learning ability (r=-.480, p<.001), and learning satisfaction (r=-.236, p<.001). self-directed learning ability showed a significant positive correlation with learning satisfaction (r=.524, p<.001). The regression model for the factors affecting the learning satisfaction of the subjects was statistically significant (F= 3.027, p<.001). The major influential factors of learning satisfaction were grade (𝛽=.154, p=.013), satisfaction with school life (𝛽=.168, p=.032), and satisfaction with non-contact learning environment (𝛽=-.141, p=.028). The explanatory power was 28 %. Conclusion : These results indicate that it is necessary to reduce academic stress and increase self-directed learning ability to enhance learning satisfaction in nursing students through blended learning. In addition, the development and operation of a tailored intervention program is required to help improve learning satisfaction.

• 한국산업융합학회 논문집
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• 제24권6_2호
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• pp.715-727
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• 2021

This research is to investigate the concept of Local Housing Association, and stepwise implementation procedure, through the theoretical consideration, and then to find out overall problems happening in the process of pushing ahead with Local Housing Association, including problems in the corresponding business stage, based on the cases of Local Housing Association that have been appearing in Changwon areas, Gyeongnam, and to present legal and policy directions for solutions to it, based on it. First, regarding improvement measures at the stage of promotion committee, it is necessary to introduce the system to report the establishment of promotion committee to cities, provinces, and districts under the jurisdiction of the location of overall business, for the establishment of association. In order to secure the professionalism of promotion committee, it is necessary to enforce those members to receive education and training for a certain period, and improve the system to post on Website or through public notices. Second, regarding improvement measures at the stage of the approval of establishment, Local Housing Association have difficulties in replacing members and joining new memberships, after getting the approval of the establishment, which can put the brake on business operation. Finally, in order to prevent crime actions, such as embezzlement or breach of duty, in advance, it is necessary to establish the institutional system that allows every member to check details of business fund. It is expected that this research would minimize side effects incurred by Local Housing Association System and help Local Housing Association take full institutional responsibility and play an axis of housing supply policy.

• Journal of Chest Surgery
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• 제55권3호
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• pp.189-196
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• 2022

Background: This study investigated the predictive value of the frailty index calculated using laboratory data and vital signs (FI-L) in patients who underwent coronary artery bypass grafting (CABG). Methods: This study included 508 patients (age 67.3±9.7 years, male 78.0%) who underwent CABG between 2018 and 2021. The FI-L, which estimates patients' frailty based on laboratory data and vital signs, was calculated as the ratio of variables outside the normal range for 32 preoperative parameters. The primary endpoints were operative and medium-term all-cause mortality. The secondary endpoints were early postoperative complications and major adverse cardiac and cerebrovascular events (MACCEs). Results: The mean FI-L was 20.9%±10.9%. The early mortality rate was 1.6% (n=8). Postoperative complications were atrial fibrillation (n=148, 29.1%), respiratory complications (n=38, 7.5%), and acute kidney injury (n=15, 3.0%). The 1- and 3-year survival rates were 96.0% and 88.7%, and the 1- and 3-year cumulative incidence rates of MACCEs were 4.87% and 8.98%. In multivariable analyses, the FI-L showed statistically significant associations with medium-term all-cause mortality (hazard ratio [HR], 1.042; 95% confidence interval [CI], 1.010-1.076), MACCEs (subdistribution HR, 1.054; 95% CI, 1.030-1.078), atrial fibrillation (odds ratio [OR], 1.02; 95% CI, 1.002-1.039), acute kidney injury (OR, 1.06; 95% CI, 1.014-1.108), and re-operation for bleeding (OR, 1.09; 95% CI, 1.032-1.152). The minimal p-value approach showed that 32% was the best cutoff for the FI-L as a predictor of all-cause mortality post-CABG. Conclusion: The FI-L was a significant prognostic factor related to all-cause mortality and postoperative complications in patients who underwent CABG.

• Journal of Chest Surgery
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• 제55권2호
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• pp.151-157
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• 2022

Background: We investigated surgical outcomes after the surgical repair of cor triatriatum sinister (CTS). Methods: Thirty-two consecutive patients who underwent surgical repair of CTS from 1993 through 2020 were included in this study. The morphological characteristics, clinical features, and surgical outcomes were described and analyzed. Results: The median age and body weight at operation were 9 months (interquartile range [IQR], 3-238 months) and 7.5 kg (IQR, 5.8-49.6 kg), respectively. There were 16 males (50%). According to the modified Lucas classification, type IA (classical CTS) was most common (n=20, 62.5%). Atrial septal defect was associated in 22 patients (68.8%) and anomalous pulmonary venous return in 8 patients (25%). Pulmonary hypertension was preoperatively suspected with a high probability in 18 patients (56.3%). There was 1 early death (3.1%) after emergent membrane excision and hybrid palliation in a high-risk hypoplastic left heart syndrome patient. There were no late deaths. The overall survival rate was 96.9% at 15 years post-repair. No early survivors required reoperation during follow-up. Most survivors (31 of 32 patients, 96.9%) were in New York Heart Association functional class I at a median follow-up of 74 months (IQR, 39-195 months). At the latest echocardiography performed at a median of 42 months (IQR, 6-112 months) after repair, no residual lesion was observed except in 1 patient who had moderate pulmonary hypertension (mean pulmonary arterial pressure of 36 mm Hg). Conclusion: Surgical repair of cor triatriatum could be performed safely and effectively with an extremely low risk of recurrence.

• Journal of Positioning, Navigation, and Timing
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• 제12권1호
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• pp.83-89
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• 2023

The Korea Augmentation Satellite System (KASS) system is a Satellite Based Augmentation System (SBAS) under development to provide APV-I SBAS service in the Republic of Korea. The KASS ground segment generates correction and integrity information for GPS measurements of KASS users using the accurate positions of KASS Reference Station (KRS) antenna phase centers. For this reason, the accuracy of KRS reference points through geodetic survey campaigns is one of the important factors for providing the KASS service in compliance with the required navigation performance. In order to obtain accurate positions, two geodetic survey campaigns were performed at several reference points, such as Mark, Center of Mast at Ground Level (CMGL), and Center of Hole in Top Plate (CHTP), of each KRS site using three different survey methods, the Virtual Reference Station (VRS), Flächen Korrektur Parameter (FKP), and raw data post-processing methods. By comparing and analyzing the results, the computed coordinates of the reference points were verified and Antenna Phase Center (APC) positions were calculated using KRS Antenna Reference Point (ARP) data, and the first KASS Site Acceptance Test (SAT#1) was performed successfully using the verified APC coordinates. After the first site survey activities, the KASS operators should maintain the coordinates with the required performance such that the overall KASS navigation performance commitment is guaranteed during the lifetime of 15 years. Therefore, the maintenance plan for the KRS antenna coordinates should be developed before the commissioning of KASS operation planned after 2023. Therefore, this paper presents a geodetic survey method selected for the maintenance activities and provides the rationale for using this method.

• 한국도서관정보학회지
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• 제53권3호
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• pp.119-135
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• 2022

본 연구의 목적은 도서관법 개정에 따라 의무 적용되는 공공도서관 설립 타당성 사전평가가 도서관의 질적인 측면을 개선할 수 있을지 파악하는 것이다. 이에 도서관법 개정 전 같은 목적으로 시행되었던 공공도서관 건립지원 사업 사전평가의 사례 분석을 통해 사전평가의 실효성을 분석하였다. 사전평가를 거쳐 건립된 도서관들의 경우 도서관법 시행령에서 요구하는 법정 사서 최소 기준 3명을 대부분 확보하고 있어 기본적인 도서관 인력 확보에는 도움이 된다고 할 수 있었다. 하지만 당초 계획하였던 만큼의 인력을 확보하여 운영하는 도서관은 거의 존재하지 않았고 신청서에는 도서관 운영을 직접 운영하겠다고 신청하였지만 실제 개관 시 위탁운영으로 변경된 사례도 있어 사전 검토 내역이 충실히 반영되지 않았다는 측면도 있었다. 본 연구는 사례 분석을 통하여 형식적으로 거쳐야 하는 사전 절차가 되지 않도록 법 개정에 따른 현실성 있는 사서 배치 기준의 재확립과 도서관 등록제를 활용한 사후평가 도입을 제안하였다.

• 한국안전학회지
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• 제38권3호
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• pp.43-50
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• 2023

Silicone tetrachloride (SiCl₄) leak accidents cause enormous human and environmental damage because it is highly toxic. Some handling facilities use water curtains to reduce the impact range of SiCl₄. Although the water curtain is known as one of the most efficient technologies for post-release mitigation, its effect on reducing SiCl₄ concentration needs to be investigated scientifically and quantitatively. In this study, three-dimensional computational fluid dynamics (CFD) was used to investigate the physical and chemical effects of water curtains as a release-mitigation system for SiCl₄. SiCl₄ is released and dispersed five seconds prior to the operation of the water curtain. Once the water curtain works, the SiCl₄ reacts chemically with the water and its concentration decreases rapidly; it reaches an emergency response planning guidelines level 2 (ERPG-2) of 5 parts per million (ppm) at about 570 m. We observed, however, that the physical effect of water curtains on reducing SiCl₄ concentration is insignificant when the chemical effect is eliminated. These results are crucial since they can be a scientific and quantitative basis for the 'technical guidelines for estimating the accident affected range'. In order to protect the public from chemical accidents, more toxic gas mitigation technologies need to be developed.