• Title/Summary/Keyword: elapsed time

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Realization of signifiers and mathematics understanding: Focused on the elapsed time (기표의 구현과 수학적 이해: 경과시간을 중심으로)

  • Han, Chaereen
    • The Mathematical Education
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    • v.60 no.3
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    • pp.249-264
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    • 2021
  • This article is devoted to investigating young learners' understanding of elapsed time from socio-cultural perspectives. The socio-cultural perspective benefits to access and personalize mathematics learning as how to have a mathematical object to be able to realize signifiers with the help of many other mathematical words and mediators. In terms of the realization of signifiers, I analyzed performances on elapsed time tasks of students in Grades 3 (n=115) and interviewed focal students. Quantitative analysis on students' performance identified that students perform differently when the task provided with the analog clock signifier. It suggested that students might think in a different way upon the given signifier even for the same elapsed time, especially when given as the analog clock. Qualitative analysis on focal students' interviews visualized how the students' understanding were different by displaying individual realization trees on elapsed time. The particular location of the analog clock signifier on each realization tree provided a personalized explanation about low performance on the task with analog clock signifier. The finding suggested that the realization of a specific signifier could be a key point in elapsed time understanding. I discussed why a majority of students face difficulty in elapsed time learning indicated analog clock and the advantage of moving elapsed time strands to higher grades in the school mathematics curriculum.

Analysis of Learning Opportunities Provided in Elapsed Time Instruction: Focusing on Quantitative Objectification (경과시간 수업에서 제공되는 학습기회 분석: 양적 대상화를 중심으로)

  • Han, Chaereen
    • Education of Primary School Mathematics
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    • v.24 no.4
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    • pp.203-216
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    • 2021
  • Seeing the elapsed time as a quantity that can be measured is quite challenging for students while making students see it is also challenging for teachers. Tuning on these challenges, this article reports on what learning opportunities elementary teachers provide when they teach elapsed time focusing on quantitative objectification. I observed three mathematics classrooms where the elapsed time was taught by three elementary teachers and did a narrative analysis on the instructions. All three teachers utilized certain tools to support students access to the elapsed time as a quantity. They appropriated various quantitative attributes of the tool. In the case of the analog clock, one teacher tried to quantification the elapsed time with the number of minute hand's turning, while the other teacher indicated the distance of minute hand's moving. One teacher represented the elapsed time with the longitudinal attribute of the time band. Standing on the findings, the didactical implications of various attempts for quantitative objectification of the elapsed time implemented were discussed.

Clinical Analysis of Symptoms and Oriental Medical Prescriptions According to Elapsed Time of Stroke in Oriental Medical Hospital Inpatients

  • Yun, Hen-Ja;Sung, Kang-Keyng
    • Herbal Formula Science
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    • v.20 no.1
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    • pp.133-147
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    • 2012
  • Objectives : This study was intended to understand characteristics of symptoms, oriental medicine prescription and laboratory test results according to elapsed time of stroke. Methods : Through the medical records of 205 stroke inpatients in the oriental medical hospital in the year 2010, we investigated manifested symptoms, administered oriental medicine prescription and clinical pathological examination results. Collected items were classified to depend on stroke types, cerebral infarction and hemorrhage. We analyzed association between manifested symptoms, the oriental medicine prescription, and laboratory test results of stroke patients and elapsed time. Chi-square tests were performed to determine the significance level of association. Results : All symptoms, prescriptions and laboratory test results in cerebral infarction patients were associated with elapsed time. Especially, symptoms, prescriptions and pathological examination results showed very high statistical significance with elapsed time (a symptom; chi-square(df)=164.3(22), p<0.001, prescription; chi-square(df)=93.5(22), p<0.001, and pathological examination results; chi-square(df)=164.3(22), p<0.0004). But in the case of cerebral hemorrhage, there was not statistical significance. Conclusions : The elapsed time of stroke may be an essential requisite in catching symptoms and prescribing for stroke patients in oriental medical treatment.

The Factors Affecting Retirement Adjustment by Elapsed Time from Middle-Aged & Advanced-Aged Retiree's Retirement (중고령 은퇴자들의 은퇴 후 경과기간별 은퇴생활적응의 영향요인)

  • Kim, Ji-Kyung;Song, Hyun-Ju
    • Journal of the Korean Home Economics Association
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    • v.48 no.6
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    • pp.83-101
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    • 2010
  • Using the first wave of KLoSA(Korean Longitudinal study of Aging) beta version, this study analyzed factors affecting retirement adjustment by elapsed time from retiree's retirement through Binary Logit and Multinomial Logit Analysis. Participants were 1,780 retiree. The main results of this study were as follows : First, The retiree's education(-), health status(-), region(+), dwelling type(-), monthly household income(-), employment type before retirement(+), retirement reason(+), and the elapsed time from retirement(-) were affected whether they satisfied with pre-retirement or not. Second, The gender(-), age(-), and the region(+) were affected whether they satisfied with life after retirement or not. Third, The gender(-), age(-), education(+), heath status(+), dwelling type(+), monthly household income(+), retirement reason(-), and the elapsed time from retirement(+) were affected on their satisfaction after retirement compared to pre-retirement. Last, The different factors affected the life satisfaction after retirement by elapsed time from retirement.

Study on the Behavior and Damage of Pedestrian at Car Body Impact (차체 충돌에 있어서의 보행자의 거동 및 손상에 관한 연구)

  • Cho, Jae-Ung;Han, Moon-Sik
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.20 no.2
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    • pp.157-161
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    • 2011
  • The study for traffic safety improvement is so necessary to minimize the wound of pedestrian at car impact as to prevent pedestrian from this accident. This study aims at analyzing the behavior affected by impact on which car body hits pedestrian. Load and damage of pedestrian are also investigated. This model is the small car body as frame structure. The pedestrian is modeled with dummy by CATIA as Korean standard body style. The ear impacts the side of pedestrian with the speed from 30 to 90km/h. Behavior and damage of pedestrian at impact are analyzed by ANSYS. In case of 30km/h, The maximum pressure of dummy becomes the maximum value of 100MPa after the elapsed time of 0.1second and then seems to remain at 105MPa constantly. In case of 60km/h, its pressure becomes the maximum value of 110MPa at the elapsed time of 0.05second and decreases at 90MPa until the elapsed time of 0.1second. This value fluctuates after the elapsed time of 0.1second. In case of 90km/h, its maximum pressure becomes the maximum value of 155MPa at the elapsed time of 0.07second and fluctuates after the elapsed time of 0.07second until O.3second. This value seems to remain at 100MPa constantly after 0.3second until 0.5second. But this pressure increases suddenly just after 0.5second. Maximum deformations of dummy increase linearly according to elapsed time at hitting velocities of 30, 60 and 90km/h.

A Study of Elapsed Time Change on Concrete for Top-Down Method (역타공법 적용을 위한 콘크리트 경시변화 특성 연구)

  • 정근호;이종균;박선길;이영도;정상진
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.487-492
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    • 1999
  • The purpose of this study to find the mixture of concrete for Top-Down method. Throughout test of elapsed time change and L-type flow, it was proposed basic performance and level of top-down method concrete. When change as to elapsed time is considered, so series of F10 added 10% S.P satisfied slump and demanded flow (60$\pm$5cm), and L-type slump, L-type flow satisfied liquidity, it can be considered basic mixture of designed actual frame later.

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Impedance Characteristics of Blue Fluorescent OLED According to Elapsed Time (경과 시간에 따른 청색 형광 OLED의 Impedance 특성)

  • Kong, Do-Hoon;Yang, Jae-Woong;Ju, Sung-Hoo
    • Journal of the Korean institute of surface engineering
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    • v.50 no.5
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    • pp.405-410
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    • 2017
  • In order to study current-voltage-luminance and impedance characteristics according to elapsed time, a blue fluorescent OLED was fabricated. The current density and luminance gradually decreased in accordance with elapsed time and did not emit light after 480 hours, and the threshold voltage increased as time elapsed. The Cole-Cole plot was a semicircular shape of a very large size at 2 V of the applied voltage below the threshold voltage, and the maximum value of the real number impedance did not change greatly from 9314.5 to $9902.2{\Omega}$ as time elapsed. Applied voltages 4, 6, and 8 V above the threshold voltage showed a large change in the real number impedance value at the semicircle end to 9,678.2, 9,826, $9,535.4{\Omega}$ according to the elapsed time from 2,222.5, 183.7, $48.2{\Omega}$ immediately after fabricating the device. By increasing the applied voltage beyond the threshold voltage just after device fabrication, the energy difference between the device and the organic layer was overcome and the current flowed, the maximum value of the real number impedance sharply decreased. As time passed, current did not flow through the element even at high applied voltage due to degradation of the element, and even when the applied voltage was higher than the threshold voltage, it showed an impedance value such as applied voltage equal to or less than the threshold voltage. As a result, it can be learned that the change in the impedance with elapsed time reflects the characteristics due to the degradation of the OLED and can predict the characteristics and lifetime of the OLED.

Error Analysis of Reaction Wheel Speed Detection Methods (반작용휠 속도측정방법의 오차 분석)

  • Oh, Shi-Hwan;Lee, Hye-Jin;Lee, Seon-Ho;Yong, Ki-Lyuk
    • Journal of Astronomy and Space Sciences
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    • v.25 no.4
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    • pp.481-490
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    • 2008
  • Reaction wheel is one of the actuators for spacecraft attitude control, which generates torque by changing an inertial rotor speed inside of the wheel. In order to generate required torque accurately and estimate an accurate angular momentum, wheel speed should be measured as close to the actual speed as possible. In this study, two conventional speed detection methods for high speed motor with digital tacho pulse (Elapsed-time method and Pulse-count method) and their resolutions are analyzed. For satellite attitude maneuvering and control, reaction wheel shall be operated in bi directional and low speed operation is sometimes needed for emergency case. Thus the bias error at low speed with constant acceleration (or deceleration) is also analysed. As a result, the speed detection error of elapsed-time method is largely influenced upon the high-speed clock frequency at high speed and largely effected on the number of tacho pulses used in elapsed time calculation at low speed, respectively.

EPET-WL: Enhanced Prediction and Elapsed Time-based Wear Leveling Technique for NAND Flash Memory in Portable Devices

  • Kim, Sung Ho;Kwak, Jong Wook
    • Journal of the Korea Society of Computer and Information
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    • v.21 no.5
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    • pp.1-10
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    • 2016
  • Magnetic disks have been used for decades in auxiliary storage devices of computer systems. In recent years, the use of NAND flash memory, which is called SSD, is increased as auxiliary storage devices. However, NAND flash memory, unlike traditional magnetic disks, necessarily performs the erase operation before the write operation in order to overwrite data and this leads to degrade the system lifetime and performance of overall NAND flash memory system. Moreover, NAND flash memory has the lower endurance, compared to traditional magnetic disks. To overcome this problem, this paper proposes EPET (Enhanced Prediction and Elapsed Time) wear leveling technique, which is especially efficient to portable devices. EPET wear leveling uses the advantage of PET (Prediction of Elapsed Time) wear leveling and solves long-term system failure time problem. Moreover, EPET wear leveling further improves space efficiency. In our experiments, EPET wear leveling prolonged the first bad time up to 328.9% and prolonged the system lifetime up to 305.9%, compared to other techniques.

Stress Analysis of Blanking Plate Applied by Press (프레스에 의한 블랭킹 판재의 응력 해석)

  • Cho, Jae-Ung;Han, Moon-Sik
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.7 no.2
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    • pp.66-71
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    • 2008
  • The data of the deformation and the stress according to time are studied at upper model of press and lower model of the blanking plate applied by press with the width, length and height of 0.4 m and 0.6 m respectively. The press is pushing downward on the plate fixed at the lower floor. These data are compared and investigated through this study. By using these results, there is the maximum deformation at 4 corners in the lower plate model of aluminium alloy fixed at lower floor. This deformation incase of elapsed time of 0.6 second becomes 4 times as much as in case of elapsed time of 0.2 second. The quantity of deformation at the lower plate model becomes more than at the upper press model to the extent of 10%. At the lower plate model of aluminium alloy, there is the maximum Von-Mises equivalent stress at 4 corners and both sides of middle area on the lower plate model of aluminium alloy. This stress in case of elapsed time of 0.6 second becomes 6 times as much as in case of elapsed time of 0.2 second. The Von-Mises equivalent stress of lower plate model becomes 2 times as much as that of upper press mode.

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