• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권5호
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• pp.2499-2522
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• 2017

Multi-hop networks are a low-setup-cost solution for enlarging an area of network coverage through multi-hop routing. Carrier sense multiple access with collision avoidance (CSMA/CA) is frequently used in multi-hop networks. Multi-hop networks face multiple problems, such as a rise in contention for the medium, and packet loss under heavy-load, saturated conditions, which consumes more bandwidth due to re-transmissions. The number of re-transmissions carried out in a multi-hop network plays a major role in the achievable quality of service (QoS). This paper presents a statistical, analytical model for the end-to-end delay of contention-based medium access control (MAC) strategies. These strategies schedule a packet before performing the back-off contention for both differentiated heterogeneous data and homogeneous data under saturation conditions. The analytical model is an application of Markov chain theory and queuing theory. The M/M/1 model is used to derive access queue waiting times, and an absorbing Markov chain is used to determine the expected number of re-transmissions in a multi-hop scenario. This is then used to calculate the expected end-to-end delay. The prediction by the proposed model is compared to the simulation results, and shows close correlation for the different test cases with different arrival rates.

• 임상간호연구
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• 제23권1호
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• pp.30-39
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• 2017

Purpose: The aim of this study was to evaluate the effects of favorite music therapy on the stress response of hysterectomy patients undergoing general anesthesia. Methods: Date were collected from June 29, 2015 to January 18, 2016 and the participants were 79 hysterectomy patients (experimental group 40 and control group 39). The experimental group listened to their favorite music through earphones from the moment they entered the surgical waiting room until they exited from the post anesthesia care unit. Results: There were statistically significant differences in anxiety (F=15.92, p<.001), systolic blood pressure (F=4.23, p=.008), diastolic blood pressure (F=3.07, p=.033), and heart rate (F=19.93, p<.001) between participants in the experimental group and the control group according to measurement times. Conclusion: The study results show that favorite music therapy considering patients' preferences is effective in reducing anxiety among patients undergoing a hysterectomy under general anesthesia, thus leading to a stable change in their blood pressure and heart rate.

• Industrial Engineering and Management Systems
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• 제15권3호
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• pp.278-288
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• 2016

Automation ensures accurate and well-organized container transportation in container terminals. This paper addresses operational issues such as equipment scheduling and the coordination between various pieces of equipment in a rail-based automated container terminal. Containers are relayed using multiple types of equipment from road trucks to a vessel and vice versa. Therefore, handshaking is required during a container transfer between different pieces of equipment. Synchronization between the schedules of all the equipment is important to reduce equipment waiting times and the time required for transporting containers, which results in a short turnaround time for a vessel. This paper proposes an integrated control system with the objective of synchronizing the operations of different types of equipment, provides a list of decisions to be made by the control module of each type of equipment, and shows all the required information transfers between control modules. A scheme for the integrated scheduling of multiple types of equipment is proposed. The decisions made by each control module in a real-time fashion are listed with detailed explanations, and the information transfer between managers in a real-time situation at the proposed terminal is described.

• 한국치위생학회지
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• 제5권2호
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• pp.247-261
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• 2005

The main objective of this study is to investigate the factors affecting patient satisfaction, repeat-use intention, and inducement intention for providing the suggestion for patient-oriented management of dental services organizations. For this study, the patient satisfaction model including 14 facets of satisfaction factors such as distance(time/location), human services(dentist-hygienist), treatment results, and facilities(convenient facilities/parking lot) was examined. Data were collected from 196 patients who visiting the same dental services organization more than two times of ten dental clinics at Kyeongsangnam-do area using self-administered questionnaire. Major results of the empirical analysis are as follows: First, patient satisfaction, repeat-use intention, and inducement intention were significantly correlated with gender, age, economic conditions among patients of dental clinics. Second, kindness of hygienist, treatment results, kindness of receptionist, waiting time, emergency medical services, and right-fee for services were found to have significant influence on dental services organizations. These research findings suggest that improvement of service quality in dental care and advancement in treatment ability of dentist and hygienist are very important to improve patient satisfaction and patient-oriented service system in dental services organizations.

• Journal of Biosystems Engineering
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• 제27권2호
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• pp.79-88
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• 2002

This study was conducted to develop system for high speed rice transplanting machines. The control system includes a sensor detecting the tilt angle of the seedling bed, a micro-controller and a hydraulic system consisting of a double acting cylinder, a four-way three-position solenoid valve, a relief valve and a hydraulic pump. The levelling system shared the pump with the existing steering control, resulting in a tandem center circuit for the steering and levelling control systems. Using the input signal from the sensor, the micro-controller determined and generated the output signal to control the cylinder through the solenoid valve to keep the seedling bed always parallel to the water surface regardless of soil unevenness during the transplanting operations. Both an ON/OFF and a PWM control schemes were tested. When the flow rate was more than 1 ι/min in the ON/OFF control, the system showed unstable rolling. However, in the PWM control, the system worked stably although the flow rate was more than 1 ι/min. The PWM control showed a better performance when a large difference between the angle and the dead band of the control system occurred. The characteristics of tile system response to given tilt angles were predicted by a computer simulation. Both the ON/OFF and the PWM control systems worked well providing that the operating and waiting times were properly adjusted.

• 한국실내디자인학회논문집
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• 제15권1호
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• pp.106-112
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• 2006

Buildings undergo changes by various factors according as pass at time. Due to that social requests and issues form one common sense of value and this would influence the architect's design intention. In fact, the form and function of buildings have coped with transition of the common sense of value by each times. Hospital architecture is also changed in function, scale and technology since, Kwanghyewon which was the first western style hospital in Korea was established in 1885. It is changing that the social needs for hospital which was a basic function of healing to laying emphasis on the function of precaution. According to this, the change of hospital spaces means that it can promote healing environment which is expanded from the modern concept of isolation, accommodation and urban sanitation. These changed concepts were adopted limited areas in hospitals at first however, nowadays they are expanding to other areas. So, this is caused to make the image of the hospital. From this point of view, Entry space is an example to show the changes. This study is intended to determine the overall space structure of entry area and to classify and analyze the difference.

• Journal of the Korean Statistical Society
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• 제32권3호
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• pp.311-311
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• 2003

This paper contains the following errors. 1. "$I_{\{x>D\}}{\lambda}dt_{p0}(t)s(x)$" should be added to the right hand side of (2.3). 2. "$I_{\{x>D\}}{\lambda}_{p0}(t)s(x)$" should be added to the right hand side of (2.6). 3. "$I_{\{x>D\}}{\lambda}_{p0}s(x)$" should be added to the right hand side of (2.9). 4. In Theorem 2.3 and its proof, "${\lambda}{\int}_{0}^{D}f(y)s(x-y)dy$" appears three times (including one in (2.20)). To each of these, "${\lambda}_{po}s(x)$" should be added. 5. In Remark 2.5, "${\lambda}dt_{p0}/s(x)dx" should be added to "${\int}_{0}^{D}{\lambda}dt\;s(x-y)dxf(y)dy$". As a result of these corrections, a simpler proof of Theorem 2.3 becomes available. Substituting (2.18), (2.21), (2.22) into the left hand side of (2.20) and comparing the result with (2.10), we have the right hand side of (2.20).

• 대한교통학회지
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• 제23권2호
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• pp.131-142
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• 2005

버스 운행 정시성은 운행계획에 따라 정시에 운행하는 정도를 나타낸다. 이용자의 대기시간은 버스 운행의 정시성에 직접적으로 영향을 받기 때문에 정시성지표는 이용자 관점에서 버스 운행의 신뢰성을 평가하는 지료로 가장 널리 사용되는 평가척도 중 하나이다. 그러나 실제 버스 운행은 도로여건, 교통상황, 승객수요 등 여러 가지 상황에 의해 사전에 작성된 운행 계획을 준수하지 못하게 된다. 따라서 여러 가지 상황에 따라 버스 운행의 정시성을 평가할 수 있는 정시성 지표를 개발하여 제시한다. 또한 서울시에서 운행하는 여러 버스 노선의 운행 자료를 분석하여 정시성 지표를 산출하였으며 이를 통해 여러 가지 운행 여건에 따른 정시성지표의 변화 특성을 분석하였다.

• 도시과학
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• 제7권2호
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• pp.1-9
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• 2018

In this study, Analysis of DRT model and contribustion based on the case of local governments adopting the Demand Responsive Transit(DRT) in order to provide transportation in public transportation service weak area. Based on the case of Yeoju Area, the contribution of the DRT was analyzed. The DRT model was established as a fixed and call type model with taxi and bus transportation. Based on the results of the happy taxi service in Yeoju Area in 2016, the contribution of DRT was analyzed. According to the happy taxi performance of Yeoju city, it was introduced to 27 villages, and operated 4,188 times. And 9,111 people used it and Yeoju Area supported about 53 million Won. The contribution of local governments was analyzed in terms of local government, users, and social aspects. On local government aspects, we analyzed the budget cuts and complaints resolution. On the user aspects, we analyzed waiting time reduction, walking time reduction, travel time reduction, comfort, punctuality, and stability. On social aspects, we analyzed taxi and regional economy activation, and convenience of mobility.

• 천문학회보
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• 제44권1호
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• pp.63.2-63.2
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• 2019

Eight hundred thousand asteroids in the solar system have been identified so far under extensive sky surveys. Kilometer to sub-km sized asteroids, however, are still waiting for discovery, and their size and orbital distribution will provide a better understanding of the collisional and dynamical evolution of the solar system. In order to study the number of asteroids which is detectable with 1.6 m telescope and their orbital distribution, we conducted a small observation campaign as a part of Deep Ecliptic Patrol of the Southern Sky (DEEP-South) project, which is an asteroid survey in the southern hemisphere with Korea Microlensing Telescope Network (KMTNet). We observed the ecliptic plane near opposition ($2^{\circ}{\times}2^{\circ}$ field of view centering on ${\alpha}=22h40m31s$, ${\delta}=-08^{\circ}22^{\prime}58^{{\prime}{\prime}}$) in August 2018, and identified 464 moving objects by visual inspection. As a result, 266 of 464 moving objects turn out to be previously unknown asteroids, and their signal to noise ratio is below two on numerous occasions. Most of the newly detected objects are main belt asteroids (MBAs), while three Hildas, one Jupiter trojan, and two Hungarias are also identified. In this meeting, we report the differences in the orbital distributions between the previously known asteroids and newly discovered ones using statistical methods. We also talk about the observational bias of this survey and suggest future works.