• Journal of Trauma and Injury
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• 제32권2호
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• pp.80-85
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• 2019

Purpose: To compare the time intervals to magnetic resonance imaging (MRI) and surgical treatment in patients having traumatic cervical spinal cord injury (SCI) with and without bony lesions. Methods: Retrospectively analyzed adult patients visited Kyungpook National University Hospital and underwent surgical treatment for cervical SCI within 24 hours. The patients who were suspected of having cervical SCI underwent plain radiography and computed tomography (CT) upon arrival. After the initial evaluation, we evaluated the MRI findings to determine surgical treatment. Waiting times for MRI and surgery were evaluated. Results: Thirty-four patients were included. Patients' mean age was 57 (range, 23-80) years. Patients with definite bony lesions were classified into group A, and 10 cases were identified (fracture-dislocation, seven; fracture alone, three). Patients without bony lesions were classified into group B, and 24 cases were identified (ossification of the posterior longitudinal ligament, 16; cervical spondylotic myelopathy, eight). Mean intervals between emergency room arrival and start of MRI were 93.60 (${\pm}60.08$) minutes in group A and 313.75 (${\pm}264.89$) minutes in group B, and the interval was significantly shorter in group A than in group B (p=0.01). The mean times to surgery were 248.4 (${\pm}76.03$) minutes in group A and 560.5 (${\pm}372.56$) minutes in group B, and the difference was statistically significant (p=0.001). The American Spinal Injury Association scale at the time of arrival showed that group A had a relatively severe neurologic deficit compared with group B (p=0.046). There was no statistical significance, but it seems to be good neurological recovery, if we start treatment sooner among patients treated within 24 hours (p=0.198). Conclusions: If fracture or dislocation is detected by CT, cervical SCI can be easily predicted resulting in MRI and surgical treatment being performed more rapidly. Additionally, fracture or dislocation tends to cause more severe neurological damage, so it is assumed that rapid diagnosis and treatment are possible.

• 산업경영시스템학회지
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• 제39권2호
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• pp.1-10
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• 2016

In this paper, we present a new way to derive the mean cycle time of the G/G/m failure prone queue when the loading of the system approaches to zero. The loading is the relative ratio of the arrival rate to the service rate multiplied by the number of servers. The system with low loading means the busy fraction of the system is low. The queueing system with low loading can be found in the semiconductor manufacturing process. Cluster tools in semiconductor manufacturing need a setup whenever the types of two successive lots are different. To setup a cluster tool, all wafers of preceding lot should be removed. Then, the waiting time of the next lot is zero excluding the setup time. This kind of situation can be regarded as the system with low loading. By employing absorbing Markov chain model and renewal theory, we propose a new way to derive the exact mean cycle time. In addition, using the proposed method, we present the cycle times of other types of queueing systems. For a queueing model with phase type service time distribution, we can obtain a two dimensional Markov chain model, which leads us to calculate the exact cycle time. The results also can be applied to a queueing model with batch arrivals. Our results can be employed to test the accuracy of existing or newly developed approximation methods. Furthermore, we provide intuitive interpretations to the results regarding the expected waiting time. The intuitive interpretations can be used to understand logically the characteristics of systems with low loading.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2018년도 춘계학술대회
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• pp.57-58
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• 2018

사물인터넷에 대한 관심이 증가하면서 사물인터넷을 활용하여 사물 간 주고받은 정보를 처리하는 기술들이 연구되고 있다. 특히 컨테이너 터미널이 자동화 됨에 따라 터미널 내에 사물인터넷의 사용이 증가하고 다양화되었다. 그러나 컨테이너 터미널 운영의 효율성을 향상시키기 위한 사물인터넷의 활용은 미흡한 단계이다. 현재 컨테이너 터미널은 외부 트럭의 도착패턴이 특정시간에 집중되는 현상이 나타난다. 이에 따라 게이트 혼잡이 발생하고 트럭의 대기시간에 영향을 준다. 이로 인해 항만 인근지역의 환경오염 문제, 사회적 문제 등으로 피해가 발생한다. 따라서 본 논문에서는 컨테이너 터미널의 게이트 혼잡도에 영향을 미치는 외부트럭의 대기시간 문제의 원인을 분석하고 사물인터넷 환경에서 이를 완화하기 위한 방안을 연구하고자 한다.

• 정보처리학회논문지C
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• 제9C권5호
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• pp.709-718
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• 2002

클러스터 기반 VOD 서버는 동시에 여러 사용자에게 실시간으로 서비스하기 위해 정교한 부하 분산 기술과 버퍼 관리 기술을 요구한다. 본 논문에서는 클러스터 기반 VOD 서버에서의 동적 버퍼 분할을 이용한 새로운 부하 분산 방법을 제안한다 제안된 방법은 사용자 요구를 처리하는 VOD 서비스 노드간의 버퍼 성능과 디스크 접근 빈도를 고려하여 전체 부하를 고르게 분산하도록 한다. 또한 동적 버퍼 분할 방법은 동일한 연속미디어에 접근하려는 여러 사용자에게 평균 대기시간을 감소시킬 수 있도록 버퍼를 동적으로 분할한다. 시뮬레이션을 통해 제안된 방법이 기존의 방법보다 부하량을 적절히 조절하면서 평균 대기시간을 감소시키고, 각 노드의 처리량도 증가시킨다. 특히, VOD 서버 클러스터가 과부하 상태일 때 제안된 방법이 Generalized Interval Caching에 기반한 부하 분산 방법 보다 약 2배의 우수한 성능을 나타냄을 시뮬레이션을 통하여 입증한다.

• 한국환경과학회지
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• 제28권7호
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• pp.581-594
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• 2019

This research investigated the characteristics of $PM_{10}$ and $PM_{2.5}$ concentrations at the main subway stations in Busan. Annual mean $PM_{10}$ concentrations at the Seomyeon 1- waiting room and platform were $51.3{\mu}g/m^3$ and $47.5{\mu}g/m^3$, respectively, and the annual $PM_{2.5}$ concentration at the Seomyeon 1- platform was $28.8{\mu}g/m^3$. $PM_{2.5}$/$PM_{10}$ ratio at Seomyeon 1-platform and Dongnae station were 0.58 and 0.53, respectively. Diurnal variation of $PM_{10}$ concentration at subway stations in Busan was categorized into four types, depending on the number of peaks and the times at which the peaks occurred. Unlike the areas outside of the subway stations which reported maximum $PM_{10}$ concentration mostly in spring across the entire locations, the interiors of the subway stations reported the maximum $PM_{10}$ concentration in spring, winter, and even summer, depending on their location. $PM_{10}$ concentration was highest on Saturday and lowest on Sunday. The numbers of days when $PM_{10}$ concentration exceeded $100{\mu}g/m^3$ and $80{\mu}g/m^3$ per day over the last three years at the subway stations in Busan were 36 and 239, respectively. The findings of this research are expected to enhace the understanding of the fine particle characteristics at subway stations in Busan and be useful for developing a strategy for controlling urban indoor air quality.

• 한국환경과학회지
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• 제28권7호
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• pp.595-606
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• 2019

This research investigated the characteristics of CO, $CO_2$, and $NO_2$ concentrations at main subway stations in Busan. The annual mean CO concentrations at the Suyeong and Nampo stations were 0.75 ppm and 0.48 ppm, respectively. Annual $CO_2$ concentration at the Seomyeon 1- platform was 649 ppm. The $NO_2$ concentrations at the Seomyeon 2- waiting room and the Yeonsan station were 0.048 ppm and 0.037 ppm, respectively. CO concentration was highest at two times of the day, and was proportional to the number of passengers commuting to and from work. The CO and $CO_2$ concentrations were highest in winter, but $NO_2$ concentration was highest in spring. CO and $CO_2$ concentrations were highest on Saturday and lowest on Sunday. The correlation of CO and $NO_2$ concentrations measured at the subway stations with those at the ambient air quality station were highest at the Seomyeon 1 and 2- waiting room and Jeonpodong. The correlation was lowest at the Yeonsan and Yeonsandong station. The number of days when $CO_2$ concentration exceeded 700 ppm over the last three years at the Seomyeon 1- platform was 174. The findings of this research are expected to deepen understanding of the fine particle characteristics at subway stations in Busan and be useful for developing a strategy for controlling urban indoor air quality.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 전기설비전문위원
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• pp.195-197
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• 2009

It is a proven fact with the opening of the Seoul metro line number 1 in 1974 traffic congestion on the roads has decreased and the efficiency of people transportation in general has greatly been enhanced in the downtown and surrounding areas of Seoul. Even today construction of new subway lines are under way and many more are being planned due to the easy access to stations, short waiting and average travel times, compared with personal vehicles, contributing to the efficiency of the public transportation systems that are linking the downtown areas and also the intercity systems in moving passengers during rush hour and times of special event. Since the labour costs of the train operator in any large city based subway system accounts for a major part of the operating costs per kilometer and to ensure cost efficient operations, especially during non-peak hours, it is necessary to implement an unmanned(auto-driven) subway system. In order to implement such a system it is imperative that the on-board and wayside signalling control systems be fully automated as well. Only through proper examination of safety procedures not only by the AUGT(Automated Urban Guided Transport)system but also by ail the international standards organizations involved can safely and stability be ensured.

• 정보처리학회논문지A
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• 제8A권2호
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• pp.117-124
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• 2001

At NOW (Networks Of Workstations), the load sharing is very important role for improving the performance. The known load sharing strategy is fixed-granularity, variable-granularity and adaptive-granularity. The variable-granularity algorithm is sensitive to the various parameters. But Send algorithm, which implements the fixed-granularity strategy, is robust to task granularity. And the performance difference between Send and variable-granularity algorithm is not substantial. But, in Send algorithm, the computing time and the communication time are not overlapped. Therefore, long latency time at the network has influence on the execution time of the parallel program. In this paper, we propose the preSend algorithm. In the preSend algorithm, the master node can send the data to the slave nodes in advance without the waiting for partial results from the slaves. As the master node sent the next data to the slaves in advance, the slave nodes can process the data without the idle time. As stated above, the preSend algorithm can overlap the computing time and the communication time. Therefore we reduce the influence of the long latency time at the network and the execution time of the parallel program on the NOW. To compare the execution time of two algorithms, we use the $320{\times}320$ matrix multiplication. The comparison results of execution times show that the preSend algorithm has the shorter execution time than the Send algorithm.

• 한국초등과학교육학회지:초등과학교육
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• 제24권5호특별호
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• pp.583-594
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• 2005

The purpose of this study was to investigate beginning elementary teachers' characteristics and improvement of their teaching skills in science class. The methodology of this study was a qualitative approach that included interviews, classroom observations, and teaching materials. In urban area, low beginning elementary teacher were selected. Four beginning elementary teachers were observed and recorded with VCR in their classroom at seven-times. The results showed that the beginning elementary teachers did not improve in their teaching skills in science teaching, and their characteristics of teaching skills in science were summarized as following; 1) their teaching methods were not inquiry-based science teaching, but explaining-based science teaching, 2) their main aims of the science teaching were focused on the science knowledges, 3) there were little students' science processes involved in their classes, 4) they focused on using textbook as teaching materials, 5) there were little waiting times after their questioning, and they usually used closed-questions rather than open-ended questions.

• ETRI Journal
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• 제32권1호
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• pp.84-92
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• 2010

This paper proposes the semaphore authority management (SAM) controller to optimize the dual-port SDRAM (DPSDRAM) in the mobile multimedia systems. Recently, the DPSDRAM with a shared bank enabling the exchange of data between two processors at high speed has been developed for mobile multimedia systems based on dual-processors. However, the latency of DPSDRAM caused by the semaphore for preventing the access contention at the shared bank slows down the data transfer rate and reduces the memory bandwidth. The methodology of SAM increases the data transfer rate by minimizing the semaphore latency. The SAM prevents the latency of reading the semaphore register of DPSDRAM, and reduces the latency of waiting for the authority of the shared bank to be changed. It also reduces the number of authority requests and the number of times authority changes. The experimental results using a 1 Gb DPSDRAM (OneDRAM) with the SAM controllers at 66 MHz show 1.6 times improvement of the data transfer rate between two processors compared with the traditional controller. In addition, the SAM shows bandwidth enhancement of up to 38% for port A and 31% for port B compared with the traditional controller.