• Earthquakes and Structures
• /
• v.9 no.5
• /
• pp.999-1028
• /
• 2015

Despite the fact that the fundamental period appears to be one of the most critical parameters for the seismic design of structures according to the modal superposition method, the so far available in the literature proposals for its estimation are often conflicting with each other making their use uncertain. Furthermore, the majority of these proposals do not take into account the presence of infills walls into the structure despite the fact that infill walls increase the stiffness and mass of structure leading to significant changes in the fundamental period numerical value. Toward this end, this paper presents a detailed and indepth analytical investigation on the parameters that affect the fundamental period of reinforce concrete structure. The calculated values of the fundamental period are compared against those obtained from the seismic code and equations proposed by various researchers in the literature. From the analysis of the results it has been found that the number of storeys, the span length, the stiffness of the infill wall panels, the location of the soft storeys and the soil type are crucial parameters that influence the fundamental period of RC buildings.

• KCI Concrete Journal
• /
• v.12 no.1
• /
• pp.121-130
• /
• 2000

This study focused on evaluating the reliability of code formulas such as those of the current Korean Building Code(KBC 1988). UBC 1997, NBCC 1995. and BSLJ 1994 for estimating the fundamental period of RC apartment buildings with shear-wall dominant systems, representative of typical residential buildings in Korea. For this purpose, full-scale measurements were carried out on fifty RC apartment buildings, and these results were compared to those obtained by code formulas and also by dynamic analysis. Although these code formulas are based on the measured periods of buildings during various earthquakes and building period varies with the amplitude of structural deflection or strain level, ambient surveys should provide an effective tool for experimentally verifying the design period to the completed building. This comparison shows that comparatively large errors are likely to occure when the code formula of KBC 1988 is used, and all the other code formulas are not sufficient to estimate the fundamental period of apartment buildings with shear-wall dominant systems. An improved formula is proposed by regression analysis on the basis of the measured period data. The proposal is for the servicebility stress level, but it can also be applied for seismic code in the regions of low seismicity similar to Korea.

• Journal of the Korean Home Economics Association
• /
• v.34 no.5
• /
• pp.85-98
• /
• 1996

This study was undertaden to investigate the effect of salted anchovy during Puchukimchi fermentation, Puchukimchi is a kind of Korean kimchi made with Puchu(Allium odorum L.). For this purpose, the Puchukimchi with 10%, 15% and 30% salted anchovy was investigated by measuring physicochemical, microbiological and sensory characteristics during fermentation at 5$\pm$2$^{\circ}C$ up to 60 days, In the palatable period, pH was remarkably decreased to the range of 4.8-5.16 and total acidity was increased 2-3 times more than that of initial period. Reducing sugar contents in Puchukimchi increased up to 22days and remarkably decreased. The changing pattern of vitamin C drawed sigmoidal curve, invreasing significantly in the palatable period. The content of lactic acid was a little in the initial fermentation period but increased 3-13 times more than that of the initial fermentation period in the palatable period. The content of malic acid and citric acid were decreased as the fermentation progressed. The contents of Ca, Mg and K was gradually decreased and Na was increased as the fermentation progressed in the same period. There were similiar changes in the number of lactic acid bacteria and total cell number. The score of overall taste, overall acceptability in evaluation during fermentation was high in order of 15%, 10%, 30% level of salt fermented anchovy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.1
• /
• pp.515-519
• /
• 2005

Pitch period that is a important factor in speech signal processing is used in various applications such as speech recognition, speaker identification, speech analysis and synthesis. So many pitch detection algoritms have been studied until now. AMDF which is one of pitch period detection algorithms chooses the time interval from valley point to valley point as pitch period. In selection of valley point to detect pitch period, complexity of the algoritm is increased. So in this paper we proposed the simple algorithm using modified AMDF that detects global minimum valley point as pitch period of speech signal and compared existing methods with it through simulation.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.23 no.2
• /
• pp.208-219
• /
• 1999

The costume style of Turfan had changed three times which were the period of peculiar style the period of Kochang style the period of influence of T'ang's culture. Before the founding of Kochang country the costume style of Turfan was two piece style. It was a character of nomadic people's clothes. Tops were tunic and caftan. The method of adjust caftan were two types. The one is wrapping toward left so the right edge of the top covers the left. The other is wrapping toward right. Bottoms were pants and skirts. This period was characterized by the traditional style. I called in it the period of peculiar style After the founding of Kochang country style as Kochang style. In this period Silkroad was so activated that cultural exchanges between many people and materials passed through Turfan. Turfan's culture soaked up the products of civilization of chinese and western Turkestan. Chinese and western Turkestan's costume influencd under the direct control of T' ang dynasty. Such an aspects were reflected the Trufan's costume. The Trucan's costume had changed into the foreign style that was the T'ang's costume. It was the period of influence of T'ang culture.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2006.03a
• /
• pp.125-132
• /
• 2006

To estimate the local site effects at two town fortress areas where stone parapets were collapsed during historical earthquakes, site characteristics were evaluated using borehole drillings and seismic tests and equivalent-linear site response analyses were conducted based on the shear wave velocity (Vs) profiles determined from site investigations. The study sites are categorized as site classes C and B according to the mean Vs to 30 m ranging from 500 to 850 m/s, and their site periods are distributed in short period range of 0.06 to 0.16 sec. For site class C in the study areas, the short-period (0.1-0.5 sec) and mid-period (0.4-2.0 sec) site coefficients, $F_{\alpha}$ and $F_\nu$ specified in the Korean seismic design guide, underestimate the ground motion in short-period band and overestimate the ground motion in mid-period band, respectively, due to the characteristics showing high amplification in short period range, which can result in the collapse of stone parapets having the short natural period.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.24 no.2
• /
• pp.99-104
• /
• 2019

Solar power generation systems require maximum power point tracking (MPPT) control to acquire maximum power using inefficient and high-cost PV modules. Most conventional MPPT algorithms are based on the slope-tracking concept. The perturb and observe (P&O) algorithm is a typical slope-tracking method. The two factors that determine the MPPT performance of P&O algorithm are the MPPT control period and the magnitude of the perturbation voltage. The MPPT controller quickly moves to the new maximum power point at insolation change when the perturbation voltage is set to large, and the error of output power will be huge in the steady state even when insolation is not changing. The dynamics of the MPPT controller can be accelerated even though the perturbation voltage is set to small when the MPPT control period is set to short. However, too short MPPT control period does not improve MPPT performance but consumes the MPPT controller resources. Therefore, analyzing the performance of the MPPT controller is necessary for actual insolation conditions in real weather environment to determine the optimum MPPT control period and the magnitude of the perturbation voltage. This study proposes an optimum MPPT control period that maximizes MPPT efficiency by measuring and analyzing actual insolation profiles in typical clear and cloudy weather in central Korea.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2019.11a
• /
• pp.48-49
• /
• 2019

The number of disputes over defects after completion of construction work in apartment buildings is increasing every year. In this situation, the prediction of reasonable defect repair costs is very important. In this paper, we are going to collect basic data for predicting defect repair costs through the correlation analysis of the construction period and defect repair cost of apartment houses. For this purpose, first of all, the construction period and defect repair cost of apartment houses were analyzed to analyze the construction period for each type of work, the construction period for each project type, and the construction period for each standard calculation. Next, the correlation between defect repair cost and the independent variables of the candidate was conducted. According to the analysis, the ratio of framing air, the ratio of finishing air, and the number of delay days showed strong correlation.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.43 no.4
• /
• pp.123-132
• /
• 2020

Currently, there are two types of trainer in Korea : basic and advanced. Both models have been in operation for more than 10 years, and compared to the early stage of operation, reliability has gradually improved and failure rates have also entered a trend of stabilization. Therefore, it is necessary to extend the maintenance period considering economic feasibility. This study investigates the three maintenance period calculation methods: NAVAIR 00-25-403 [17], DOD, U.S. [4], CERL and US Army [3], with intention to extend the maintenance period of the trainer from current 200 hours to 400 hours. In addition, the maintenance period was calculated by the three methods with actual operational data. Common standards and procedures were established to apply operational data to the existing maintenance period calculation methods, the required reliability indicators were derived, and the maintenance periods was calculated based on the results, additionally, a review on the field applicability of the three maintenance cycles was conducted. An on-site interviews were conducted with the calculation results, and 11 out of the 15 items were expected to be extended by 400 hours. It was suggested that the remaining 4 items could be extended to 400 hours by supplementing the inspection method through additional analysis such as functional analysis, inspection content verification, and site connection.

• Korean Journal of Organic Agriculture
• /
• v.30 no.3
• /
• pp.335-350
• /
• 2022

The purpose of this study is to help operate and manage the new food period system by investigating consumer perception of sell-by-date and use-by-date, and change of purchasing and consumption period by food period label. Although they have opinions that fit the purpose of introducing the system, such as the need to introduce a use by date, extending the food intake period, and reducing food waste, they still lack an accurate understanding of the system, so education or publicity is needed. In addition, no matter what form of use by date is introduced, products with food expiration date are still likely to be returned or discarded. Therefore, it is desirable to adjust the setting criteria or safety factor for each deadline rather than changing the food period labeling method. In order to reduce consumer confusion and food waste, it is judged that the parallel marking of the sell by date and use by date is appropriate.