• The Korean Journal of Applied Statistics
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• v.28 no.3
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• pp.511-527
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• 2015

For time series analysis, power transformation (especially log-transformation) is widely used for variance stabilization or normalization for stationary ARMA(p, q) model. A simple and naive back transformed forecast is obtained by taking the inverse function of expectation. However, this back transformed forecast has a bias. Under the assumption that the log-transformed data is normally distributed. The unbiased back transformed forecast can be obtained by the expectation of log-normal distribution; consequently, the property of this back transformation was studied by Granger and Newbold (1976). We investigate the sensitivity of back transformed forecasts under several different underlying distributions using simulation studies.

• The Korean Journal of Applied Statistics
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• v.21 no.3
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• pp.537-546
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• 2008

One of main goals of time series analysis is to estimate prediction of future values. In this paper, we investigate the bias problem when the transformation and back- transformation approach is applied in ARMA models and introduce a modified smearing estimation to reduce the bias. An empirical study on the returns of KOSDAQ index via Yeo-Johnson transformation was executed to compare the performance of existing methods and proposed methods and showed that proposed approaches provide a bias-reduced estimation of the prediction value.

• Journal of the Mineralogical Society of Korea
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• v.18 no.4 s.46
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• pp.237-248
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• 2005

Results from in-situ high temperature X-ray diffraction measurements show that $Mg_{2}SiO_{4}{-}$spinel converts back to olivine phase only when heated in vacuum, and that at some high temperature, the olivine phase grows with time at the expense of the spinel phase strongly suggesting a 'nucleation and growth' type transition. In order to obtain the activation energy of spinel-olivine back transformation, kinetics measurements were performed on $Mg_{2}SiO_{4}{-}$spinel in vacuum at high temperatures between 1023 and 1116 K. Activation energy was determined using 'time to a given fraction method'. By employing the Avrami equation, it was found that n values generally increase with increasing temperature in a wide range implying that the nucleation and growth mechanism is probably temperature-dependent. It is likely that in spinel, at a relatively lower transformation temperature, after nucleation sites saturated, the growth of the new phase starts on the surface and gradually moves inwards. At high temperatures, however, after nucleation sites saturated, the growth starts both on the surface as well as at the interior.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.964-968
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• 1996

The demands of size and quality of large steel shaft forgings for ship building, power plant, steel plant, etc. are rapidly increasing, and some of these productions are manufactured from ingot weighing more than 300 tons. For use as rotating components. shafts require toughness, strength and homogeneity, and therefore are produced through a variety of heat treatments. According to the increase of ingot size, micro- and macrosegregation and also mass effect of the product increase. Thus, special care should be paid to the heat treatment of such large shaft forgings. In this paper, the heat treatment of large shaft forgings such as rotor and back-up roll is calculated using the commercial finite element code SYSWELD. Calculated distributions of temperature and phase are compared with experimental data. The continuous cooling transformation diagram, thermal and mechanical properites of each phase are used. The phase proportion, hardness and residual stress during water quenching are discussed.

• Journal of Smart Tourism
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• v.1 no.1
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• pp.69-74
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• 2021

Restaurants are an important area of the hospitality industry. This industry sector has not only experienced severe consequences of the recent lockdowns, but it has also seen the rise of digital technologies. As known from other industries, the digital transformation impacts products, processes and business models alike. Starting from the classical distinction of a restaurant's front- and back-of-the-house processes, this paper presents an overview on current developments in the restaurant industry and based on an analysis of current digital services, it derives some implications for future directions. Among the observations are that restaurants need to cover more touch points, provide more individualized offerings and strive for more automation as well as integration of their systems.

• Journal of the Korean Home Economics Association
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• v.35 no.4
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• pp.159-172
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• 1997

The purpose of this study was to investigate the slacks pattern making on the movement -fitness of the hip region. The experimental items were divided into the 5 lower limb movements(M1-M5) and the 12 revision pattern constructions of slacks. This study was done by clothing pressure test sensory evaluation test and the difference shape-transformation of wearing-slacks. The summarized finding resulted from experiments and investigation are suggested as follows: First by the clothing pressure tested by lower limb movements the clothing pressure score of the rabbit leap movement(M3) was the highest of all lower limb movements and the order of it in the another movement was the sit on knee(M4) the sit on chair(M2) the noble sitting(M5) from the highest to the lowest. And in comparision of clothing pressure tested by revision pattern to cover the extend of crotch-length 20。 inclined back-line construction method (CA4) showed the lowest. And in comparision of clothing pressure tested by revision pattern to cover the extend of crotch-length 20。 inclined back-line construction method (CA4) showed the lowest. And also for a role to cover hip circumference extendign CC4(1/5 hip.1cm longrightarrow linked back -line) method showed the lowest. Second by the sensory evaluation test based on the movement and revision patterns it was found that the functional factor score of the rabbit leap movement was the lowest in all movement however the score of revision patterns were higher than basic pattern. Third by the test to show difference in the shape-transformation of wearing-slacks on chair(M2) also need to be analyzed. The ration of the shape-transformation of the knee region showed the least value in the increased patterns of inclined angle of back-line(CA) and the differential methods of back-line inclined pattern making. But that of the hem-line did not show remarkable difference.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.6
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• pp.380-386
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• 2000

This paper presents the mathematical modelling analysis of Brushless Synchronous Motor(BLSM). The dynamic and the steady state characteristics of BLSM are simulated and analyzed : electromagnetic torque, speed, line voltage, and current. We used mathematical modelling to model of BLSM with sinusoidal back EMF, namely the shaft transformation referencing rotor frame from a, b, c three to produce constant torque like synchronous motor. The experiment result has already similar to compare with simulation result : torque error about 7%, speed error about 5%. The validity of proposed modelling and analysis was confirmed by the experimental result.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.206.1-206.1
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• 2005

• Journal of Acupuncture Research
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• v.35 no.2
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• pp.81-87
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• 2018

Background: The purpose of the present study was to evaluate efficacy and patient satisfaction of acupuncture or Chuna therapy for back pain. Methods: Amongst all the patients with back pain who had been treated at Sun-cheon korean medicine hospital, Dong-shin university, only patients that had received either acupuncture or Chuna manual therapy between September 1 and October 31, 2017 were selected and their medical charts retrospectively analyzed. A questionnaire was used in the investigation that consisted of a numeric rating scale (NRS), the Oswestry low-back pain disability index (ODI), general, emotional, conversational, and technical satisfaction. The questionnaire was completed before treatment and at weekly intervals (approximately). Treatment efficacy was analyzed using the first and last questionnaires. The last questionnaire was also used to establish patient satisfaction. The data were analyzed using SPSS for Windows version 21.0. Results: The NRS, Current degree of pain (ODI-1), and total ODI were significantly decreased in both the acupuncture and Chuna groups. The differences in NRS, ODI-1, and total ODI changes between treatment groups were not significant. There were no statistically significant differences between the acupuncture and Chuna groups in terms of general, emotional, conversational, and technical satisfaction. Conclusion: Acupuncture treatment significantly reduces NRS and ODI in patients who have back pain without structural transformation, and Chuna therapy significantly reduces NRS and ODI-1 in patients who have back pain with structural transformation. These results indicate that further studies should be conducted in more patients and over a longer period.

• Journal of Plant Biotechnology
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• v.31 no.4
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• pp.261-266
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• 2004

This experiment was carried out to confirm the stability of bar gene introduced into petunia plant through Agrobacterium-mediated transformation, in successive generation, or after crossing or back-crossing. Some of different 25 transgenic plants were used in crossing and back-crossing to wild type, or repeated-selfing to T$_4$ generation. On the processing of experiment, it was found that some lines lost their resistant ability to herbicide basta, or showed non-Mendelian segregation mode: produced much more susceptible segregants than resistant plants. Even though there are exceptional cases, which was off from expected, the genetic stability of bar gene introduced could be confirmed strongly, because in almost case, the segregation of resistant and susceptible plants to basta was done under Mendelian-law according to single gene dominant model.