• Journal of the Korea Society of Computer and Information
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• v.18 no.12
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• pp.1-9
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• 2013

Even though the multiple pages TLB are effective in improving the performance, a conventional method with OS support cannot utilize multiple page sizes in user application. Thus, we propose a new multiple-TLB structure supporting multiple page sizes for high performance and low power consumption without any operating system support. The proposed TLB is organised as two parts of a S-TLB(Small TLB) with a small page size and a L-TLB(Large TLB) with a large page size. Both are designed as fully associative bank structures. The S-TLB stores small pages are evicted from the L-TLB, and the L-TLB stores large pages including a small page generated by the CPU. Each one bank module of S-TLB and L-TLB can be selectively accessed base on particular one and two bits of the virtual address generated from CPU, respectively. Energy savings are achieved by reducing the number of entries accessed at a time. Also, this paper proposed the simple 1-bit LRU policy to improve the performance. The proposed LRU policy can present recently referenced block by using an additional one bit of each entry on TLBs. This method can simply select a least recently used page from the L-TLB. According to the simulation results, the proposed TLB can reduce Energy * Delay by about 76%, 57%, and 6% compared with a fully associative TLB, a ARM TLB, and a Dual TLB, respectively.

• Korean Journal of Optics and Photonics
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• v.28 no.3
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• pp.116-121
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• 2017

In this paper, a Raman spectrometer is designed to detect chemicals contaminating the ground. The system is based on Raman spectroscopy, which is spectral analysis of scattered light from chemicals, induced by a laser. The system consists of a transmitting-optics module with a laser to induce Raman-scattered light from the sample, a receiving-optics module to collect the scattered light, and a spectrograph to separate the collected light into a wavelength spectrum. The telescope, a part of the receiving-optics module, is designed to produce a focal spot in the same position for variable measurement distances using the code V simulator, considering the distance change between the system and the road. The Raman spectra of 12 chemicals on a glass surface and on a concrete sample were measured. Intensity differences between the Raman spectra acquired on a glass surface and on a concrete sample were observed, but the characteristics of the spectra according to the chemicals on them were similar. Additionally, the Raman spectrum of PTFE (polytetrafluoroethylene) was measured at various distances. The measured and simulated optical throughputs were similar. In conclusion, it is confirmed that with this system the Raman spectrum can be measured, irrespective of the distance change.

• Korean Journal of Optics and Photonics
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• v.32 no.2
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• pp.68-78
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• 2021

A subminiature catadioptric omnidirectional optical system (SCOOS) with 2 mirrors, 6 plastic aspherical lenses, and an illumination system of 6 light emitting diodes, to observe the 360° panoramic image of the inner intestine, is optically designed and evaluated for a capsule endoscope. The total length, overall length, half field of view (HFOV), and F-number of the SCOOS are 14.3 mm, 8.93 mm, 51°~120°, and 3.5, respectively. The optical system has a complementary metal-oxide-semiconductor sensor with 0.1 megapixels, and an illumination system of 6 light-emitting diodes (LEDs) with 0.25 lm to illuminate on the 360° side view of the intestine along the optical axis. As a result, the spatial frequency at the modulation transfer function (MTF) of 0.3, the depth of focus, and the cumulative probability of tolerance at the Nyquist frequency of 44 lp/mm and MTF of 0.3 of the optimized optical system are obtained as 130 lp/mm, -0.097 mm to +0.076 mm, and 90.5%, respectively. Additionally, the simulated illuminance of the LED illumination system at the inner surface of the intestine within HFOV, at a distance of 15.0 mm from the optical axis, is from a minimum of 315 lx to a maximum of 725 lx, which is a sufficient illumination and visibility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.195-205
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• 2021

As Coronavirus disease 2019 (COVID-19) became a pandemic, most nursing departments in Korea implemented online non-face-to-face practices rather than the existing practice method. This study was a qualitative study that analyzed the reflection diaries written by participants to understand what they experienced in the online non-face-to-face adult nursing practice process. The online non-face-to-face adult nursing practice was 90 hours for two credits and nine hours per day for a total of 10 days. This online practice consisted of computer-based simulation practice, computer-based nursing skills practice, video and educational material production, real-time online quiz, online lecture video, and discussion. As a result of analyzing the reflection diary, six categories, 13 subcategories, and 33 codes were derived. The six categories were 'Experience of various situations', 'Experience of new study', 'Fulfillment for the clinical practice', 'Building relations with professors', 'Fear of being a pre-nurse', and 'Ambivalence for the non-face-to-face practice'. These results are significant in that in the post-corona era, adult nursing practice was conducted as a non-face-to-face practice rather than a clinical practice institution, and various educational methods were operated. This study is expected to provide important basic data for the development and operation of non-face-to-face adult nursing practice.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.587-593
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• 2021

Since 2017, a total of 29 fire accidents have occurred in energy storage systems (ESSs) as of June 2020. The common mode voltage (CMV) is one of the electrical hazards that is assumed to be a cause of those fire accidents. Several cases of CMV that violate the allowable insulation level of a battery section are being reported in actual ESS operation sites with △-Y winding connections. Thus, this paper evaluates the characteristics of CMV. An ESS site was modeled with an AC grid, PCS, and battery sections using PSCAD/EMTDC software. As a result of a simulation based on the proposed model, it was confirmed that characteristics of CMV vary significantly and are similar to actual measurements, depending on the grounding method of the internal transformer for PCS. The insulation level of the battery section may be severely degraded as the value of CMV exceeds the rated voltage in case of a grounding connection. It was found that the value of CMV dramatically declines when the internal transformer for PCS is operated as non-grounding connection, so it meets the standard insulation level.

• Journal of vocational education research
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• v.37 no.1
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• pp.1-29
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• 2018

The purpose of this study is to examine how the nursing teacher in vocational high school operates the class and examine various perceptions about the operation education. Moreover, This is to comparing the difference between nursing experience and education major about the operation the class. Based on the above findings, First, the nursing teacher should be recognized as a professional subject teacher and should have a qualification system that is appropriate as a professional subject teacher. Second, a formal education program should be established so that those who worked in the nursing field can become teachers of nursing education. It is recommended that nursing education within the graduate school of education be newly established and operated only for nursing graduates who are majored in the same country as developed countries. Third, if the establishment of qualifications and qualifications system can not be realized in a short time, it is necessary to systematically prepare the training for specialization nursing teachers only.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.15-22
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• 2019

Awireless sensor network utilizes small sensors with a low cost and low power being deployed over a wide area. They monitor the surrounding environment and gather the associated information to transmit it to a base station via multi-hop transmission. Most of the research has mainly focused on static sensors that are located in a fixed position. Unlike a wireless sensor network based on static sensors, we can exploit drone-based technologies for more efficient wireless networks in terms of coverage and energy. In this paper, we introduce a transmission power model and a video encoding power model to design the network environment. We also explain a priority mapping scheme, and deploy drones oriented for network coverage and energy consumption. Through our simulations, this research shows coverage and energy improvements in adrone-based wireless sensor network with fewer sensors, compared to astatic sensor-based wireless sensor network. Concretely, coverage increases by 30% for thedrone-based wireless sensor network with the same number of sensors. Moreover, we save an average of 25% with respect to the total energy consumption of the network while maintaining the coverage required.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.28-34
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• 2019

Solar energy is one of the most abundant renewable energy sources on Earth but there are restrictions on the use of solar thermal energy due to the time-discrepancy between the solar-rich season and heating demand. In Europe and Canada, a seasonal solar thermal energy storage (SSTES), which stores the abundant solar heat in the summer and uses the heat for the winter heating load, is used. Recently, SSTES has been introduced in Korea and empirical studies are actively underway. In this study, a $2,000m^2$ flat plate type solar collector and $20,000m^2$ of borehole thermal energy storage (BTES) were studied for a greenhouse in Hwaseong City, which has a heating load of 2,164 GJ/year. To predict the dynamic performance of the system over time, it was simulated using the TRNSYS 18 program, and the solar fraction of the system with the control conditions was investigated. As a result, the solar BTES system proposed in this study showed an average solar fraction of approximately 60% for 5 years when differential temperature control was applied to both collecting solar thermal energy and discharging BTES. The proposed system simplified the configuration and control method of the solar BTES system and secured its performance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.2
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• pp.107-113
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• 2019

In this paper, a robust filter based wind velocity estimation algorithm without an air velocity sensor in an air vehicle is presented. The wind velocity is useful information for the air vehicle to perform precise guidance and control. In general, the wind velocity can be obtained by subtracting an air velocity which is obtained by an air velocity sensor such as a pitot-tube, and a ground velocity which is obtained by a navigation equipment. However, in order to simplify the configuration of the air vehicle, the wind estimation algorithm is necessary because the wind velocity can not be directly obtained if the air velocity measurement sensor is not used. At this time, the aerodynamic coefficient of the air vehicle changes due to the turbulence, which causes the uncertainty of the system model of the filter, and the wind estimation performance deteriorates. Therefore, in this study, we propose a wind estimation method using $H{\infty}$ filter to ensure robustness against aerodynamic coefficient uncertainty, and we confirmed through simulation that the proposed method improves the performance in the uncertainty of aerodynamic coefficient.

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.642-647
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• 2018

In this paper, an unequal power divider based on adjusting electrical length of uniform transmission line is presented. This divider consists of three uniform transmission lines and one isolation resistor and have the different port impedances of input and output. The feature of proposed divider can changed the power dividing ratio to adjust only electrical length of uniform transmission lines. To verify the feasibility of proposed power divider, two divider circuits are designed, one is 1:2 power dividing ratio divider with $60{\Omega}$ uniform transmission line and $40{\Omega}$ input port impedances and $45{\Omega}$ output port impedances, the performance data were measured the insertion losses of 1.7 dB/ 5.0 dB, return losses of more than -30 dB and isolation of more than -35 dB. The other is 1:4 power dividing ratio divider with $40{\Omega}$ uniform transmission line and $50{\Omega}$ input port impedances and $75{\Omega}$ output port impedances, the performance data were measured the insertion losses of 1.3 dB/ 6.8 dB, return losses of more than -12 dB and isolation of more than -19 dB. The measured performance data agreed well with the simulated results.