• School Mathematics
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• v.7 no.3
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• pp.269-286
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• 2005

The purpose of this paper is to study the spatial sense that is introduced for the first time in our 7th mathematics curriculum. For this purpose, we first investigated the factors of the spatial sense ability and with this factors, we analyze the errors those was founded in elementary school students' carrying out tasks related to the spatial sense, and the contents of elementary mathematics textbook. From the analysis, we found that the teaching topics in the spatial sense is disagreed with the students' learning level and for each similar topics is cut off into not adjacent grades, connecting these topics to each other and to the other traditional geo-metric topics is not easy. we must consider this findings in the future revision of mathematics curriculum.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.2
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• pp.129-136
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• 2017

PURPOSE: The purpose of this study was to compare the gait of elderly patients with and without dementia to investigate the possibility of an ambulation assessment test as a diagnostic tool for dementia. METHODS: A total of 96 subjects were included with 60 participants without dementia (control group) and 36 patients with dementia (dementia group). To compare the walking ability of the two groups, a 4-m walking test (4MWT) and Groningen Meander Walking Test (GMWT) were conducted. The GMWT is graded by amount of time in seconds and by number of oversteps outside the track. Mann-Whitney U test was used to compare the gait between the groups and the area under the curve (AUC) with Received Operating Characteristic (ROC) curve was analyzed. Statistical significance was considered at a p<.05, with a 95% confidence interval. RESULTS: There were statistically significant differences (p<.05) between the dementia group and the control group for the 4MWT, GMWTSEC, and GMWTSTEP scores. The AUC was .95 for 4MWT, .92 for GMWTSEC, and .96 for GMWTSTEP with the 95% confidence interval. The cut-off values of the ROC curve were 1.03m/s for 4MWT, 10.8 second for GMWTSEC, and 3.75 steps for GMSTEP. CONCLUSION: In our study, we investigated the utility of ambulatory assessment tools to predict dementia. The results of this study suggest that the 4MWT and the GMWT used in this study are appropriate assessment tools for dementia prediction.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.4
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• pp.373-379
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• 2016

The thermal control device for the periodic working component combined solid-liquid phase change material (PCM) with heat pipes is designed and numerically studied. Due to high latent heat and retaining constant temperature during melting process the component peak temperature, not withstanding small radiator size, is reduced. The warm-up heater power consumption to keep the minimum allowed temperature is also cut down since the accumulated thermal energy is released through the solidification. The thermal buffer mass (TBM) made of Al can give the similar effect but the mass and power consumption of warm-up heater should increase compared to PCM. The amount of PCM can be optimized depending on the component heat dissipation and on/off duty time.

• Asian Journal of Turfgrass Science
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• v.10 no.3
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• pp.263-270
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• 1996

This experiment was conducted to investigate the loss of various herbicides by means of vola-tility from the turfgrass field and the hare ground with the different soil moisture contents and temperatures. Different herbicides were applied at the rates of 375 g a.i. /l0a of pendimethalin,250 g a.i. /l0a of napropamide, and 96.4 g a.i. /l0a of dicamba with 200 \ulcorner/10a of spray volume in the turfgrass(Zoysia japonica cut off 5cm) grown in pots(265.8 $cm^2$) and bared soil. The pots were placed in the growth chamber with 10,000 lux of light intensity(12h per day) at 25 and 35˚C for 7days. Amberlite XAD polymeric resin(20/50 mesh) was used as sampling media for herbicide airborne residues. Air flow was maintained at 10 \ulcorner /min by vacuum pump regulated with a factory calibrated flow meter. Herbicide airborne residues were extracted from the XAD resin with 300 ml of 1:1 acetone and hexane. The extracts were concentrated by rotary evaporation at 35˚C and dissolved in 1 ml MeCN for HPLC analysis. The airborne losses of the herbicide applied in the turfgrass and bare soil increased as the temperature and soil moisture contents were increased, regardless of the kinds of herbicide. Higher airborne residues was observed in the turfgrass pots than the bare soil pots. Pendimethalin and dicamba with higher vapor pressure gave rise to the increased loss of airborne herbicides, showing that 6.26 and 6.4% of average airborne loss in pendimethalin and dicamba, respectively, compared to 0.56% in napropamide. The amount of airborne losses in turfgrass was highest at one day after application and then a declined trend was observed as the time was prolonged. Key words. Herbicides, Turfgrass field, Bare ground, Volatility.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.10
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• pp.77-83
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• 2004

In low-power VLSI systems, it is effective to suppress leakage current by shutting down megablocks in idle states. Recently, multi-threshold voltage CMOS (MTCMOS) is widely accepted to shutdown power supply. However, it requires short wake-up time as operating frequency increases. This causes large current surge during wake-up process, and it often leads to system malfunction due to severe Power line noise. In this paper, a novel wake-up scheme is proposed to solve this problem. It exploits pipelined wake-up strategy in several stages that reduces maximum current on the power line and its corresponding power line noise. To evaluate its efficiency, the proposed scheme was applied to a multiplier block in the Compact Flash memory controller chip. Power line noise in shutdown and wake-up process was simulated and analyzed. From the simulation results, the proposed scheme was proven to greatly reduce the power line noise compared with conventional schemes.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.5
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• pp.106-113
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• 2010

If leakage current is neglected, it can become a cause for disasters such as electric shock and fire, therefore a continuous monitoring is necessary. However in most cases, because management of substations is performed by unmanned systems, or walk-around inspections, continuous monitor is difficult. So when an accident occurs and the cause is not immediately resolved causing the emergency generator's OCGR getting activated by the leakage current that in turn cut off the ACB, the emergency generator may stop working. To prevent such a problem, a real-time integrated monitoring system for monitoring the leakage current returning to the grounding wire of neutral point of the low voltage side of transformer is proposed. Therefore in this paper, the effects of flow of leakage current, which is caused by insulation degradation phenomena or insulation destroy phenomena, were identified by simulation. And through cases studies; the excellence of integrated monitoring system was verified.

• The Journal of the Acoustical Society of Korea
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• v.36 no.1
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• pp.49-56
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• 2017

This paper proposes a method to improve the left right discrimination performance by eliminating the imaginary target based on the frequency features of the beam pattern for bow array. The beamwidth of the imaginary target is wider than that of the real target. If an azimuth axis is considered as a time axis, the real and the imaginary targets can be assumed as high and low frequencies, respectively. To eliminate the imaginary target which has a low frequency component, we design a cut-off frequency of the High Pass Filter (HPF) using the back-lobe imaginary beamwidth. The real target is estimated by eliminating the imaginary target by applying HPF to the entire power of the beamformer output. Computer simulations show that the proposed method can increase the left right discrimination performance above 8 dB on average.

• Journal of Korean Clinical Nursing Research
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• v.26 no.2
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• pp.265-273
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• 2020

Purpose: The purpose of this study was to test the predictive validity of the Fall Assessment Scale-Korean version (FAS-K) and to find the most appropriate cutoff score to screen high-risk fall groups in adult patients in general hospitals in Korea. Methods: We performed a prospective evaluation study in medical and surgical ward patients at two major general hospitals in Seoul. Data were collected from Nov. 1, 2018 to Feb. 28, 2019, nurses performed 651 observation series. The researcher measured the fall risk assessment score by applying FAS-K, MFS (Morse Fall Scale), and JHFRAT (Johns Hopkins Hospital Fall Risk Assessment tool) to the patients twice a week between 10 am and 12 noon. Data were analyzed using Pearson's corelation coefficients, and the sensitivity, specificity, predictive value, and the area under the curve (AUC) of the three tools. Results: The FAS-K was positively correlated with the MFS (r=.70, p<.001) and the JHFRAT (r=.82, p<.001). According to the receiver operating characteristics (ROC) curve analysis of the FAS-K, sensitivity, specificity, and positive and negative prediction values were 85.3%, 49.4%, 8.5%, and 98.4%, respectively, when the FAS-K score was 4. Therefore, the cut-off score of the FAS-K to identify groups with high fall risk was 4. Conclusion: The FAS-K is a valid tool for measuring fall risk in adult inpatients. In addition, the FAS-K score, 4, can be used to identify high-risk fall groups and know specific points in time to provide active interventions to prevent falls.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.7
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• pp.1299-1304
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• 2011

A wind turbine (WT) should be shut down as fast as possible to minimize its own damage in a storm-driven situation. Shutdown of a large wind farm requires a power grid to have a ramp-up capability large enough to balance between generation and consumption of electrical energy. This paper proposes a supervised shutdown algorithm of a wind farm to meet a required ramp-down rate in a grid code in the case of a storm-driven situation. The information on the speed and the direction of wind is measured at a wind mast (WM) installed around a wind farm. If the wind speed exceeds a cut-out speed, the number of WTs to be shut down simultaneously is decided to meet a required ramp-down rate of a grid-code. Arrival times to each WT from the WM are calculated and sorted in the order of time. Then a sequence of groups is generated. The shutdown start/end times of each group are decided to avoid superposition between adjacent two groups. The performance of the proposed shutdown algorithm is verified under various storm scenarios. Results indicate that the proposed algorithm can not only protect the wind farm in the case of a storm-driven situation but also meet the required ramp-down rate. In addition, the algorithm can produce more energy than that of a conventional shutdown algorithm.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.465-468
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• 2008

Recently, VOD market is getting increased and most of public, educational organization, enterprises are providing service as content managing system of WMV standard subordinated to Window OS of Microsoft company. VOD CMS of WMV standard have problem that frequent cut-off, small-size of screen, and image quality which is also chronic problem. In order to solve this problem, technology solving the problem has developed through minimization of buffering time, screen size, high quality sound, and high quality image by image codec and streaming engine which is H. 264. But there are still a problem that systematic management of contents or distribution is difficult. This study expected that there would be a effect preoccupying significant stand of world wide H.264 high quality image mobile VOD managing market by securing domestic on-line VOD contents integrated managing technology by designing system for image VOD contents management having a limit in wmv market and combining H.264 which is new technology.