• Journal of Korea Multimedia Society
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• v.15 no.7
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• pp.879-884
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• 2012

In this Paper, we propose an Energy Efficient Time Synchronization technique based on WUSB (Wireless USB) over WBAN (Wireless Body Area Networks) protocol required for Wearable Computer systems. For this purpose, the proposed Time Synchronization algorithm minimizes power consumption and estimates time information with accuracy. It is executed on the basis of WUSB over WBAN protocol at each sensor node comprising peripherals of a wearable computer system. It minimizes power consumption by exchanging time stamp packets and forming a hierarchical structure.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.157-163
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• 2003

IEEE 802.11a Distributed Coordination Function(DCF) Protocol을 사용하여 Real-Time MultiMedia Data의 전송을 수행할 경우, DCF Protocol의 적합하지 못한 Mechanism에 의하여, Data 전송의 극대화를 이루지 못한다. Retransmission이 반복되는 경우, Binary Slotted Exponential Backoff Mechanism은 거대한 Packet Delay와 Jitter의 원인이 되며 Automatic Repeat Request(ARQ) 방식의 Ack Mechanism은 MultiMedia Data를 전송하기에 적합하지 못하다. 본 논문은 위와 같은 문제점을 해결하기 위하여 Real-Time MultiMedia Data을 주로 전송하는 STA에 따른 Real-Time/Non-Real-Time(RT/NRT) Station(STA)의 구분과 보내고자 하는 Real-Time MultiMedia Data의 Network Traffic Load(The Required Bandwidth)를 고려하여, Modified DCF(mDCF) Protocol의 Modified Backoff(mBackOff), Modified BlockAck(mBlockAck) Mechanism을 제시함으로서, Data 전송의 극대화를 제공하며, 또한 IEEE 802.11a와의 호환성을 제공한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.9 no.4
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• pp.170-178
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• 1984

For the reduction of the 12-channel TDM/FDM translation time the 14-point fast DCT algorithm is used and the polyphase network which translates the prototype filter into the channel filters required in each channel is designed. For the prototype filter the degree of the numerator is 168 and the coefficients have symmetry values, the degree of the numerator is 6. Such a prototype filter is consistant with the CCITT requirements. In this case the required multiplication rate is CCITT requirements. In this case the required multiplication rate is $0.12267{\times}10^2$ multiplications/sec. channel and reduces to about 15-40% of the rate required in the exising systems. The proposed 12-channel TDM/FDM translation system is simulated using a demodulation system with a computer (PRIME 750) and the results show that the proposed conversion method is valid.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.1
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• pp.51-58
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• 2021

Chemical decontamination of primary systems in a nuclear power plant (NPP) prior to commencing the main decommissioning activities is required to reduce radiation exposure during its process. The entire process is repeated until the desired decontamination factor is obtained. To achieve improved decontamination factors over a shorter time with fewer cycles, the appropriate flow characteristics are required. In addition, to prepare an operating procedure that is adaptable to various conditions and situations, the transient analysis results would be required for operator action and system impact assessment. In this study, the flow characteristics in the steady-state and transient conditions for the chemical decontamination operations of the Kori-1 NPP were analyzed and compared via the MARS-KS code simulation. Loss of residual heat removal (RHR) and steam generator tube rupture (SGTR) simulations were conducted for the postulated abnormal events. Loss of RHR results showed the reactor coolant system (RCS) temperature increase, which can damage the reactor coolant pump (RCP)s by its cavitation. The SGTR results indicated a void formation in the RCS interior by the decrease in pressurizer (PZR) pressure, which can cause surface exposure and tripping of the RCPs unless proper actions are taken before the required pressure limit is achieved.

• Journal of Biosystems Engineering
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• v.39 no.2
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• pp.101-110
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• 2014

Purpose: The purpose of this study is to develop a system to optimize drying potential energy of the exhausted hot air by changing relative humidity of the air. This study modified the conventional drying method into a drying method changing exhaust cycle and time in order to control the relative humidity of the exhausted hot air during drying process. Method: A valve on the vent was controlled according to a preset time to change the exhaust cycle and time. This study analyzed the influence of the two different types of drying method on the drying characteristics, required energy, and quality of the dried peppers: conventional drying method exhausting hot air continuously and new drying method controlling exhaust cycle and time. Results: Drying characteristics based on exhaust time showed that drying time increased with exhaust time, and specific energy consumption was reduced by 28% from 18.39 MJ/kg (conventional method) to 13.24 MJ/kg when exhaust time was set to one minute. Drying characteristics based on heating time showed that drying time increased with heating time and specific energy consumption was reduced by 30% from 18.39 MJ/kg (conventional method) to 12.87 MJ/kg when exhaust time was set to 22 minutes. Drying characteristics based on exhaust cycle showed that drying time increased with exhaust cycle, and specific energy consumption was reduced by 31% from 18.39 MJ/kg (conventional method) to 12.69 MJ/kg when exhaust time was set to one minute and exhaust cycle was set to 22 minutes before drying and 40 minutes after drying. The quality of the dried red peppers showed that capsaicin, color, and sugar content were high as 34.87 mg/100g, 66.33, and 11.87%, respectively, when exhaust time was set to one minute and exhaust cycle was set to 22 minutes before drying and 40 minutes after drying. Conclusions: In order to utilize the drying potential energy of the exhausted air during drying process, the conventional drying method was modified into the drying method controlling exhaust cycle and time. The results showed that drying with exhaust cycle of one minute was more efficient in terms of drying time, required energy, and quality of the dried peppers than the one with exhaust cycle of 20~40 minutes.

• Journal of the Korea Institute of Building Construction
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• v.18 no.4
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• pp.363-373
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• 2018

Evacuation facilities are installed so that people can evacuate high-rise apartment houses when it is impossible to escape fire through the front door. The households of apartment houses may escape the building in two ways, which will reduce loss of lives. This study examined the characteristics of two-way evacuation facilities, including a light-weight partition wall, shelter space at the balcony and horizontally-installed indoor emergency exit. Then, it proposed a horizontally-installed outdoor emergency exit that improved the problems of the examined facility types, and analyzed its economic-feasibility. When a horizontally-installed emergency exit instead of a traditional type to escape from fire is used, people may be more autonomous in deciding whether active evacuation is possible or not. Thus, the time required to evacuate the building with 4 different evacuation methods using the stairs and horizontally-installed emergency exit was simulated in consideration of the impact of evacuation methods that people choose on the time required for evacuation using pathfinder. Then, the simulation results were compared and analyzed. Any appropriate evacuation method to reduce the time required for evacuation was predicted, analyzed and decided. As a result of this study, it was analyzed that the high - rise apartment top - down type evacuation zone can shorten the total evacuation time compared to the staircase type.

• Korea Journal of Hospital Management
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• v.13 no.4
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• pp.27-45
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• 2008

This research focused on a total of 378 patients with external injuries under the age of 14 who visited the emergency center at a university hospital in Korea, during the months of January, April, August and November between January and December of 2007. In addition, the survey was conducted only on even number days and ranged across the whole year to reflect the impact of seasonal characteristics on the collected data. The research focused on determining the characteristics and inflicting cause of these patients with external injuries, analyzed the total time spent in the emergency room and obtained the following results. 1. When classifying the patients into different genders, the proportion of males (67.5%) was higher than that of females (32.5%). According to the different age groups, the highest ratio, at 61.1 %, was patients under the age of six. 2. Looking at the total number of minutes spent in the emergency room, the longest amount of time occurred during April with 162.7 minutes, followed by 121.9 minutes in January and 92.4 minutes in November. August had the shortest period of time spent in the emergency room, a significant statistical difference from the other periods of the year (p<0.001). 3. Regarding the amount of time required for each examination, patients required to provide a urine test spent an average of 204.7 minutes while those who did not spent 113.5 minutes on average. This is a 5% statistical difference among the two groups (p>0.05). 4. Looking at the five most commonly diagnosed problems in the emergency room, the total number of people with these top five commonly diagnosed illnesses comprised 55.6%, or 210 patients out of 378. 5. Utilizing the Decision Tree Model to estimate the total number of minutes required per visit, the first classifications were made using a chemical examination factor. People subject to chemical classification spent an average of 177.7 minutes, which was longer than the overall average of 115.2 minutes, and those exempt from chemical examination spent an average of 103.8 minutes, which was shorter than the average Conclusion; Effort to curtail the total time spent in emergency rooms is vital in guaranteeing efficient management of hospitals and providing medical services. The delay experienced by many comprehensive professional medical centers must be resolved through the establishment of effective delivery of medical services, increased supply of patient rooms and other policy oriented implementations. However, for now, this problem must be resolved by increasing the level of patient satisfaction and guaranteeing effective operation of patient rooms, which will significantly contribute to the general management and success of hospitals and institutions.

• Fire Science and Engineering
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• v.30 no.3
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• pp.73-78
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• 2016

The Installation, Maintence, and Safety Control of Fire-fighting Systems Act of South Korea regulates that over 30-storey high-rise buildings including underground spaces should vitally perform the Performance-based Design to minimize property damage and personal injury as a fire risk assessment in advance. Therefore a PBD designer such as a fire safety professional engineer evaluate occupant's life safety by a scientific methodology. In order to evaluate the life safety, fire safety designers calculate the Required Safety Egress Time (RSET) which does not have the legal criteria regarding the standard method of calculation yet. So this way has been showing different results depending upon the designer's choice, knowledges and experiences. In this study, RSET calculation methods by six designers respectively were analysed from the thirteen reports of real performance based design projects conducted in Busan for a last five years. In particular, the Response Time calculation methods which have the most powerful effect for figuring the RSET are compared with the other designer's to deduce an error value.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.633-640
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• 2023

With the recent development of static and dynamic modulated brachytherapy methods in brachytherapy, which use radiation shielding to modulate the dose distribution to deliver the dose, the amount of parameters and data required for dose calculation in inverse treatment planning and treatment plan optimization algorithms suitable for new directional beam intensity modulated brachytherapy is increasing. Although intensity-modulated brachytherapy enables accurate dose delivery of radiation, the increased amount of parameters and data increases the elapsed time required for dose calculation. In this study, a GPU-based CUDA-accelerated dose calculation algorithm was constructed to reduce the increase in dose calculation elapsed time. The acceleration of the calculation process was achieved by parallelizing the calculation of the system matrix of the volume of interest and the dose calculation. The developed algorithms were all performed in the same computing environment with an Intel (3.7 GHz, 6-core) CPU and a single NVIDIA GTX 1080ti graphics card, and the dose calculation time was evaluated by measuring only the dose calculation time, excluding the additional time required for loading data from disk and preprocessing operations. The results showed that the accelerated algorithm reduced the dose calculation time by about 30 times compared to the CPU-only calculation. The accelerated dose calculation algorithm can be expected to speed up treatment planning when new treatment plans need to be created to account for daily variations in applicator movement, such as in adaptive radiotherapy, or when dose calculation needs to account for changing parameters, such as in dynamically modulated brachytherapy.

• Transactions of Materials Processing
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• v.11 no.2
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• pp.155-164
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• 2002

One of the important steps on semi-solid forming Is the reheating process of raw materials to the semi-solid state. This Process is not only necessary to achieve the required SSM billet state, but also to contro1 the microstructure of the billet. In reheating process, the globule size is determined by the holding time of last heating stage. Therefore, some experiments to investigate the relationship between the mechanical properties and the holding time in the last heating stage was performed. The alloys used in this experiment were 357, 319 and A390 alloys. The experiments of reheating were performed by using an Induction heating system with the capacity of 50kw. This paper shows the evolution of the microstructure according to the holding time of last reheating stage. Furthermore, to evaluate the effect of globule size controlled by holding time in last heating stage uniaxial tension test was performed. The strain-stress curves were plotted according to the holding time.