• Journal of radiological science and technology
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• v.44 no.6
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• pp.679-688
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• 2021

This study is a questionnaire about the lesson environment that radiation major students prefer in a non-face-to-face live online lesson environment for a total of 133 students, 65 second graders and 68 third graders who are enrolled in the department of radiology at a university located in the Seoul metropolitan area. And checked the satisfactory level by grade. The questionnaire consists of three categories: 1st real-time non-face-to-face lectures, 2nd professor lectures, and 3rd corona lectures. A total of 14 questions, with multiple choice and descriptive response methods. As an evaluation method, in the case of a multiple-choice question, the average was calculated using a 5-point Likert scale. As a result of conducting the independent sample T-test of the SPSS program, the response by grade was P > 0.05, and no significant result was shown by the contents of the questionnaire survey of the second grade. As for the lecture method of the department of radiology after the end of Covid-19 virus, it is better to promote face-to-face lessons in radiation training subjects and non-face-to-face real-time education in subjects centered on radiation theory.

• Journal of Korean Association for Spatial Structures
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• v.18 no.4
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• pp.41-48
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• 2018

Recently, the concept of an outrigger damper system with a damper added to the existing outrigger system has been developed and applied for dynamic response control of high-rise buildings. However, the study on the structural characteristics and design method of Outrigger damper system is in the early stages. In this study, a 50 story high - rise building was designed and an outrigger damper system with viscoelastic damper was applied for wind response control. The time history analysis was performed by using the kaimal spectrum to create an artificial wind load for a total of 1,000 seconds at 0.1 second intervals. Analysis of the top horizontal maximum displacement response and acceleration response shows that outrigger damper systems are up to 28.33% and 49.26% more effective than conventional outrigger systems, respectively. Also, it is confirmed that the increase of damping ratio of dampers is effective for dynamic response control. However, since increasing the damping capacity increases the economic burden, it is necessary to select the appropriate stiffness and damping value of the outrigger damper system.

• Korean Journal of Construction Engineering and Management
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• v.19 no.3
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• pp.11-22
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• 2018

Existing efforts to reduce total egress time actually focused on reducing travel time. However, consideration to reduce perception time or response time was insufficient although the ratio of travel time is one-third of total egress time and situations which the safety cannot be ensured by only reducing travel time were aroused. Therefore, the concept of disaster information, which could reduce both perception time and response time got attention To analyze the effect of disaster information on occupant behaviour, this study identified a relationship between 10 major disaster information and 3 occupant behaviour factors in terms of reducing egress time. By referring the relationship, this study conducted an virtual egress experiment with survey on 4 cases, the elderly, intellectual disabled, hearing disabled and visual disabled, to identify disaster information which reduce total egress time effectively. Finally, by analyzing the experiment result, this study proposed the process of disaster information effect on occupant behaviour as complementing insufficient occupant behaviour to ensure the minimum level of safety and maximizing relatively high occupant behaviour to ensure enough level of safety. The results are expected to account for relationship between disaster information and occupant behaviour with more explanatory power in terms of egress time. With further studies of disaster information and group behaviour, these series of studies could provide basic references for disaster information and occupant behaviour.

• The Korean Journal of Applied Statistics
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• v.31 no.5
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• pp.587-597
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• 2018

Procedures, such as sampling technique, survey method, and questionnaire preparation, are required in order to obtain sample data in accordance with the purpose of a survey. An important procedure is the decision of the sample size formula. The sample size formula is determined by setting the target error and total cost according to the sampling method. In this paper, we propose a sample size formula using population changes over time, estimation error of the previous time and response rate of past data when the target error and the expected response rate are given in the simple random sampling. In actual research, we use estimators that apply complex weights in addition to design-based weights. Therefore, we induce a sample size formula for estimators using design-based weights and nonresponse adjustment coefficients, that can be a formula that reflects differences in response rates when survey methods are changed over time. In addition, we use simulations to compare the proposed formula with the existing sample size formula.

• Smart Structures and Systems
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• v.31 no.2
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• pp.101-111
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• 2023

Structural health monitoring (SHM) covers a range of damage detection strategies for buildings. In real-time, SHM provides a basis for rapid decision making to optimise the speed and economic efficiency of post-event response. Previous work introduced an SHM method based on identifying structural nonlinear hysteretic parameters and their evolution from structural force-deformation hysteresis loops in real-time. This research extends and generalises this method to investigate the impact of a wide range of flag-shaped or pinching shape nonlinear hysteretic response and its impact on the SHM accuracy. A particular focus is plastic stiffness (K_p), where accurate identification of this parameter enables accurate identification of net and total plastic deformation and plastic energy dissipated, all of which are directly related to damage and infrequently assessed in SHM. A sensitivity study using a realistic seismic case study with known ground truth values investigates the impact of hysteresis loop shape, as well as added noise, on SHM accuracy using a suite of 20 ground motions from the PEER database. Monte Carlo analysis over 22,000 simulations with different hysteresis loops and added noise resulted in absolute percentage identification error (median, (IQR)) in K_p of 1.88% (0.79, 4.94)%. Errors were larger where five events (Earthquakes #1, 6, 9, 14) have very large errors over 100% for resulted K_p as an almost entirely linear response yielded only negligible plastic response, increasing identification error. The sensitivity analysis shows accuracy is reduces to within 3% when plastic drift is induced. This method shows clear potential to provide accurate, real-time metrics of non-linear stiffness and deformation to assist rapid damage assessment and decision making, utilising algorithms significantly simpler than previous non-linear structural model-based parameter identification SHM methods.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.571-578
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• 2014

The garlic cultivation area is moved by change of grown environment due to global warming. It is important to predict changes in cultivation area, quantity and quality of each crop. This study was carried out to estimate the yield and response of garlic growth by the rapid temperature changes in the greenhouse with thermostat control system. Seedlings of Namdo garlic were planted on September 27, 2012 and harvested on May 30, 2013. The used treatments for a rapid temperature change in March-April-May were T0 (control): $6.0-10.4-17.2^{\circ}C$, T1: $6.0-5.4(-5)-17.2^{\circ}C$, T2: $6.0-10.4-22.2(+5)^{\circ}C$ and T3: $6.0-5.4(-5)-22.2(+5)^{\circ}C$. Total dried weight per plant of garlic significantly increased by 5.0% for T2, but T1 and T3 decreased by 12.5 and 4.6%, respectively, compared to T0. Total yields of bulb within the temperature change as T2 and T0 increased significantly (p<0.05), as compared to T1. Decreasing temperature significantly (p<0.05) reduced plant height, SPAD reading, crude protein and fiber contents etc., as compared to T0 and T2. ABA contents gradually increased with time but IAA content rapidly decreased. Conclusively, growth and yield of garlic were more affected by decreased temperature than increased temperature at bulb development stage.

• Current Research on Agriculture and Life Sciences
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• v.32 no.2
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• pp.67-73
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• 2014

Mulberry fruits were semi-dried using hot air ($60-100^{\circ}C$) or cool air ($20-40^{\circ}C$), and the effects of the drying temperature and processing time on the quality of the final dried mulberry fruits were investigated. Response surface methodology was employed to establish a statistical model and predict the conditions resulting in minimal loss of the total phenolic content (TPC) and ascorbic acid. Thus, using overlapped contour plots, the optimal conditions for producing semi-dried mulberry fruits, which reduced the moisture residue to 45% and minimized the nutrient losses of TPC and ascorbic acid, were determined for the hot-air process ($60.7^{\circ}C$ for 5.4 h) and cool-air process ($34.8^{\circ}C$ for 23.3 h). Plus, a higher drying temperature was found to lead to a faster loss of moisture and ascorbic acid, while the TPC was significantly decreased in the cool-air dried mulberry fruits due to the higher activity of polyphenol oxidase between 30 and $40^{\circ}C$.

• Natural Product Sciences
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• v.29 no.2
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• pp.83-90
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• 2023

To our knowledge, this is the first study aiming to optimize the extraction conditions of total phenolic compounds (TPC) and total flavonoids contents (TFC) from Argania spinosa leaves using Response Surface Methodology (RSM) with a Box-Behnken design (BBD). The optimal conditions obtained were 5% (w/v) solvent-to-solid ratio, 72.33% ethanol concentration, and 10h ours as an extraction time, which resulted in an extract with maximum TPC (131.63 mg GAE/g dw) and TFC (10.66 mg QE/g dw). Under the optimal extraction conditions, the antioxidant activity of the extracts of leaves of argan tree showed a moderate antiradical capacity of DPPH (IC₅₀ = 0,130 mg/mL) and ABTS (IC₅₀ = 0.198 mg/mL). However, the leaves of argan tree showed a very interesting reducing power of Iron (IC₅₀ = 0.448 mg/ml) which is similar to that of the ascorbic acid (IC₅₀ = 0.371 mg/mL).

• Restorative Dentistry and Endodontics
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• v.29 no.3
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• pp.226-232
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• 2004

Use of electric pulp testing elicits painful response in vital teeth. In this study, we examined the excessive time from pain feeling to stimulation disconnection in clinical situation. D626D (Parkell Inc., USA.) scan type electric pulp tester was used in total of 23 young healthy individuals. Each of the right central incisors and first premolars were used as testing teeth. Stimulation disconnection was achieved by EMG in anterior belly of digastric muscle, finger span, and voice and the excessive stimulation time over the sensory thresh-old was recorded. As a result, we found that the short responses before the stimulation disconnection appeared following order：EMG, finger span, and voice. The EMG disconnection is suggested to be used to reduce the excessive stimulus time in electric pulp testing.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.64-66
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• 1998

This paper presents a new efficient method for transient analysis in magnetodynamic systems of linear eddy current problems. This mehtod employs the Fourier transform and the high-order frequency sensitivity of harmonic finite element method. By taking into account the time-constant of magnetodynamic system, the Fourier integral of continuous frequency is converted into the Fourier series of discrete frequency. And with the results of Fourier series expansion of converted input wave form, the responses of each sinusoids is superposed to give the total response of the magnetodynamic systems. But, if the frequency band of input wave form is broad, it takes long computational time since all responses for each sinusoids must be calculated. Therefore, the high-order frequency sensitivity method is employed to estimate the response variation to frequency. The proposed algorithm is applied to an induction heating system to validate its numerical efficiency.