• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.4 s.316
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• pp.70-77
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• 2007

Two kinds of QMF(Quadrature Mirror Filter) pairs are used in JPEG2000 standard, which don't have QMF distortions. However, the QMF pairs have the main disadvantages such that there are gentle roll-off rate, ripples in the passband and unequal band decomposition. In this paper, Maxflat(maximally flat) QMF pairs with a half-band gain are proposed for overcoming these problems. Maxflat QMF pairs are realized due to generalized closed-form formulas, and the filters have maximally flat response in the passband/stopband as well as sharp roll-off rate in the transition band. Comparing proposed filters and JPEG2000's filters in frequency domain, it is found that proposed filters have better performance JPEG2000's filters. Moreover, Maxflat QMF pairs show stopband-attenuation exceeding 200 dB almost everywhere.

• Journal of the Korea Society of Computer and Information
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• v.25 no.11
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• pp.179-185
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• 2020

In this paper, we propose impact factors and validity of blood variables on death of COVID-19 patients. The clinical-epidemiological data of 5628 COVID-19 patients, provided from Korea Disease Control and Prevention Agency as day of 30th April 2020, were used. As results, impact factors of death were dementia, older age, high lymphocyte, cancer, dyspnea, COPD, change of consciousness, heart disease, high platelets, abnormal diastolic pressure and fever. The validities of blood variables for death were high in the order of lymphocyte, hemoglobin, hematocrit, platelet and WBC. Therefore, risk factors such as initial clinical characteristics, underlying disease and blood test results, could be regarded for efficient management of COVID-19 patients.

• Journal of the Korean Society for Railway
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• v.14 no.3
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• pp.300-311
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• 2011

In this study, the differences of labor-management cooperation and corporation performance resulted from integrated human resource management types is investigated for 12 urban railroad corporations and then the effect of labormanagement cooperation on the corporation performance is also verified. The results show that the labor-management cooperation and the corporation performance of "closed immersion type" and "opened flexibility type" integrated human resource managements are higher than those of "conservative management type" and "poor management type" integrated human resource managements. As a result of the effect of labor-management cooperation on the corporation performance, it is revealed that "individual cooperation" affects all the corporation performances such as train operation stability, customer's satisfaction, management innovation, self-supporting management, and job satisfaction, whereas "collective cooperation" affects only two coporation performances, management innovation and job satisfaction.

• Journal of Chest Surgery
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• v.31 no.7
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• pp.711-717
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• 1998

Background: Although various anastomotic techniques and suture materials have been used in esophageal anastomosis, anastomotic leakage and stenosis are still somewhat frequent and serious complications when compared to other intestinal anastomoses. We have used interrupted single-layer suture technique using monofilament polypropylene suture in various esophageal anastomoses, including repair of the esophageal atresia, since 1990. Methods and method: We retrospectively evaluated the efficacy of this technique on postoperative leakage and stenosis in several esophageal reconstructions. The esophageal reconstructions using this technique were performed in 90 patients at Dong-A University Hospital from April 1990 through December 1996. Results: Anastomotic leakage occurred in 5 patients(5.6%) with one operative death. Stenosis at the anastomotic site occurred in 15 patients(n=86, 17.4%), which was most common in esophagogastrostomy(22%) and least common in esophagocolostomy (5%). This result was comparable to other methods including the autosuture technique. Conclusions: We concluded that this suture technique in esophageal anastomosis can be used with reasonable results in various esophageal reconstructions including correction of the esophageal atresia.

• Journal of Chest Surgery
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• v.32 no.4
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• pp.404-407
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• 1999

Spontanous hematoma of the esophagus is a rare condition affecting middle aged or elderly women. We experienced one case of esophageal hematoma which attracted our attention due to its confusing presentation clinically. The pathogenesis has been in dispute so far. The diagnosis has traditionally been made by barium esophagogram. We proved the diagnosis of spontaneous hematoma of the esophagus by utilizing CT scan and MRI. This condition led to conservative treatment and full recovery ultimately, but we performed the surgical correction because the filling defect persisted and the dysphagia got worse on the 20th day of hospital stay. Hematoma was located between the inner layer of circular muscle and the outer layer of longitudinal muscle which we considered as intermuscular hematoma of the esophagus.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.62-62
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• 2011

한강하구지역의 강화해협은 한강, 임진강과 예성강의 강물이 흘러들어오는 하구형 수로로서 폭이 좁고, 유속이 매우 빠른 특성을 갖는다. 또한 조류(潮流)의 영향을 강하게 받아 상당량의 유량을 경기만으로 내보내고, 한강의 상류로부터 유입되는 상당량의 물질이 하구로 운반되어 침전하여 쌓이거나 하류의 외해로 배출하는 역할을 한다. 본 연구에서는 한강하류부에 위치한 강화해협의 유 무에 따른 한강과 임진강의 흐름특성 변화를 분석하였다. 수치모의를 위해 복잡한 하구지역의 물의 흐름해석이 가능한 일차원적인 모델링 도구인 MIKE 11 모형을 이용하여 정류 및 부정류 해석을 실시하였다. 상류경계조건은 홍수 시 방류량이 크게 증가하는 홍수기 유량과 조위의 영향을 많이 받는 평수기 시 유량으로 설정하였고, 하류경계조건은 평수기를 비롯하여 홍수기에도 임진강과 한강의 유량에 영향을 미치는 서해 조위로 설정하였다. 강화해협의 폐쇄에 따른 수위 변화의 영향은 홍수기 시 실제 강우 사상을 모의 하였을 때 최대 8.21% 수위가 상승하였으며, 200년 빈도 계획홍수량을 모의한 결과로는 정류 해석의 경우 최대 8.25%의 변화율을 보였고, 부정류 해석의 경우 최대 13.08%의 변화율을 보였다. 평수기는 창조기에 수위 변화가 적었던 반면 낙조기에는 창조기에 비해 수위 변동이 심하게 일어나는 것으로 나타났다. 추후 강화해협 뿐만 아니라 해양생태계의 중요한 가치를 지니고 있는 한강하구의 다른 수로에 의한 영향을 분석함으로써 수로의 중요성을 평가하고, 2차원 수치해석 등을 통한 다양한 분석을 실행하여, 홍수 및 해양환경 훼손으로부터 하구 환경을 보호하는 보다 정량적인 대응체계가 정립되어야할 것으로 사료된다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.2
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• pp.241-250
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• 2017

Contrary to past critical infrastructure network, current critical infrastructure network is adopting IoT devices and efficient management system using the external networks. Using this system, productivity and management efficiency could be enhanced compared to past critical infrastructure network. But cybersecurity issue could be occurred at external network connection, so cybersecurity guideline is necessary. However, critical infrastructure organizations tend to use the cybersecurity guideline issued by government because it is hard to develop cybersecurity guideline on their own. But the government's cybersecurity guideline isn't suitable for the critical infrastructure network because it doesn't include critical infrastructure's specific characteristics. Therefor, we suggested the development method of cybersecurity guideline for the critical infrastructure network based on analysing cybersecurity guideline standards and critical infrastructure networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1577-1582
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• 2013

In this paper, we have analyzed the performance of MIMO (Multi-Input Multi-Output) underwater acoustic communication by using the acquired data via the experiments in water tank. First of all, in the pursuit of this aim, we have measured the channel transfer characteristics at several transceiver locations. The transmitted signal was modulated by QPSK(Quadrature Phase Shit Keying) and the received signal was recovered through the detector that contains the zero forcing equalizer. A maximum 30~40 ms delay was appeared because of physically closed water tank environment that has the harsh multi-path transmission conditions. In result of experiment, even though the bit error rate showed comparatively large when $2{\times}2$ MIMO system with two transmitters and receivers was considered. However, we confirmed it has approximately 15% enhanced performance compared with SISO (Single-Input Single-Output) system.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.4
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• pp.315-321
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• 2011

The CRT monitor display system for SONAR signal that are commonly used in ships or naval vessels uses vector scanning method. Therefore the processing circuits of the system is complex. Also because production had been shut down, the supply of parts is difficult as well as high-cost. FPGA -based embedded processor system is flexible to adapting to various applications because it makes simple processing circuits and its core is easily reconfigurable, and provides high speed performance in low-cost. In this paper, we describe an implementation of SONAR signal LCD display system using the FPGA embedded processor system to overcome some weakness of existing CRT system. By changing X-Y Deflection and CRT control blocks of current system into FPGA embedded processor system, our system provides the simplicity, flexibility and low-cost of system configuration, and also real-time acquisition and display of SONAR signal.

• Journal of the Society of Disaster Information
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• v.12 no.2
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• pp.150-166
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• 2016

In the aftermath of a recent outbreak of Middle East respiratory syndrome (MERS), legal matters on the spread of epidemics have emerged as major social issues in Korea, with the awareness that rampant contagious diseases are disasters in society. Problems arose over damages arising from patients who contract infectious diseases, compensation for people under quarantine and for a partial, or entire, shutdown of hospitals, and information disclosure on infectious diseases. As epidemic-linked problems have never been socially disputed in Korea, the relevant legal issues appear to be studied comparatively less than other areas. As interests are heightened over legal issues on infectious illnesses amid the MERS scare, in-depth, further research on such legal issues should be conducted in an utmost effort to prevent and make preparations for epidemics which potentially become a social disaster, such as new Hong Kong flu, Ebola virus and Zika virus.