• Journal of the Institute of Convergence Signal Processing
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• v.23 no.1
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• pp.1-7
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• 2022

As a power transmission element, the timing belt is a toothed transmission belt that takes advantages of V-belts and gears. It has characteristics of non-slip and low noise. It is used as a power transmission device when transmitting power from a rotating shaft or linear motion in a mechanism. Rotation can be accurately transmitted through a belt pulley with grooves like a gear and a timing belt with grooves to precisely match with the belt pulley. In particular, in the mechanism in which the timing belt is used for the output shaft, the dynamic characteristics including the rigidity of the timing belt determine the transmission characteristics of the system, so its importance increases. In this paper, a stiffness reinforced belt that can be applied to a timing belt with a limited range of motion to increase its stiffness is proposed. To study the dynamic characteristics of the stiffness reinforced belt, the equation of motion for the stiffness reinforced belt was established, and a simulation model for the stiffness reinforced belt was created and analyzed. In order to confirm the analysis results of the motion equation and simulation model, a 1-axis rotation experimental equipment using a stiffness reinforcing belt was developed and the experiment was conducted. Through motion equations, simulation models, and experiment results, it was confirmed that the stiffness and dynamic characteristics of the timing belt could be improved by applying the proposed stiffness reinforcement belt.

• The Journal of the Korea Contents Association
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• v.22 no.6
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• pp.69-77
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• 2022

Physical experiment through MBL has been used in many schools for a long time since students can check the experiment results immediately and conduct the experiment easily. However, conducting the experiment, not knowing the principle of the device or simply concentrating on the derived data has been raised as the problem of MBL experiment. To supplement this problem, this study measured the acceleration of gravity with the picket fence method, which is often used in MBL experiment, utilizing Arduino, calculated the error rate through a comparison to the actual acceleration of gravity and discussed the educational application of the experiment to measure it. As a result of the experiment, the error rate between the acceleration of gravity calculated by the experiment and the actual acceleration of gravity was about 1%, so it turned out that relatively accurate measurements were possible. Also, the sample mean of the experimental value was included in the confidence interval of 95%, so it could be concluded that it was a significant experiment. In addition, this study showed the possibility of the educational application of the experiment to measure it through the following: It can supplement the structural disadvantages of MBL; it can consider the interaction between Physics and Math; it is possible to converge with information course in STEAM education; and it is inexpensive to be equipped with the equipment. Hopefully, the physical experiment utilizing Arduino will further be revitalized in science gifted education based on this study.

• Journal of the Korea Institute of Building Construction
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• v.21 no.3
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• pp.203-211
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• 2021

Recently, the insulaton design standards for reducing the energy use of buildings have been strengthened. Althoug insulation work is the most cost-effective method for reducing the primary energy consumption per unit area of a building, there are no evaluation criteria for insulation performance at the time of construction and completion inspection. The purpose of this study is to provide objective data by establishing a standard for an analysis method and a method for easily experimenting with the exterior wall thermal transmittance of an apartment house using a thermal transmittance measuring device(TESTO 435). For the exterior wall of the test subject, the specific heat per unit area exceeded 20kJ/(m²·K), and the data at the end point suitable for ISO 9869-1 were analyzed by the average method. The measured values of the thermal transmittance for 3 consecutive days converged within +5% of the desing value, and the standard deviation of the thermal transmittance by day decreased in the order of 1-Day > 3-Day > 2-Day. The standard deviation of the thermal transmittance by time period decreased in the order of 00:00~24:00 < 19:00~07:00 < 00:00~07:00. The measured value of the thermal transmittance for the time perion of 00:00 to 07:00 per day almost coincided with an error of -3% to + 2% compare to the desing value.

• Clinical and Experimental Reproductive Medicine
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• v.47 no.4
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• pp.312-318
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• 2020

Objective: The objective of the study was to compare the effects of long-term and short-term embryo culture to assess whether there is a correlation between culture duration and clinical outcomes. Methods: Embryos were divided into two study groups depending on whether their post-warming culture period was long-term (20-24 hours) or short-term (2-4 hours). Embryo morphology was analyzed with a time-lapse monitoring device to estimate the appropriate timing and parameters for evaluating embryos with high implantation potency in both groups. Propensity score matching was performed to adjust the confounding factors across groups. The grades of embryos and blastocoels, morphokinetic parameters, implantation rate, and ongoing pregnancy rate were compared. Results: No significant differences were observed in the implantation rate or ongoing pregnancy rate between the two groups (long-term culture group vs. short-term culture group: 56.3% vs. 67.9%, p=0.182; 47.3% vs. 53.6%, p=0.513). After warming, there were more expanded and hatching/hatched blastocysts in the long-term culture group than in the short-term culture group, but there was no significant between-group difference in embryo grade. Regarding pregnancy outcomes, the time to complete blastocyst re-expansion after warming is shorter in women who became pregnant than in those who did not in both culture groups (long-term: 2.19±0.63 vs. 4.11±0.81 hours, p=0.003; short-term: 1.17±0.29 vs. 1.94±0.76 hours, p=0.018, respectively). Conclusion: The outcomes of short-term culture and long-term culture were not significantly different in vitrified-warmed blastocyst transfer. Regardless of the post-warming culture time, the degree of blastocyst re-expansion 3-4 hours after warming is an important marker for embryo selection.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.3
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• pp.263-278
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• 2022

This paper contains experimental study for the development and performance of TBM backfill material with thixotropic properties. The LW backfill material is widely applied to fill the cavity on the back side of the shield TBM excavation, but has disadvantages such as settlement caused by strength reduction, material separation by groundwater, and reduced plasticity. In this paper, laboratory tests and a model test were conducted to assess the performance of inorganic thixotropic backfill material proposed to improve these problems. The results of laboratory tests show that 1 hr-uniaxial compressive strength of ITB was 12 times higher than LW, and the rate of bleeding of 20 hr was 8.3 times lower, and the result of flow table test was more than 27 times higher. This result indicated that the inorganic thixotropic backfill material has superior properties to LW backfill in terms of strength reduction, material separation, and thixotropy. In the model experiment, a model injection device tester was manufactured and the injection performance and filling rate were verified. When material was injected in the water, it was visually checked whether material separation occurred, and it was confirmed that the filling rate was 96% or more. Comparison results with the test of LW and ITB materials was concluded that ITB can reduce the material separation by groundwater and the occurrence of tunnel cavity.

• Journal of the Korea Computer Graphics Society
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• v.28 no.2
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• pp.29-41
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• 2022

In this paper, we introduce a novel real-time, interactive animation system which uses real-time motion inputs from a low-cost motion-sensing device Kinect. Our system generates interaction motions between the user character and the counterpart character in real-time. While the motion of the user character is generated mimicking the user's input motion, the other character's motion is decided to react to the user avatar's motion. During a pre-processing step, our system analyzes the reference motion data and generates mapping model in advance. At run-time, our system first generates initial poses of two characters and then modifies them so that it could provide plausible interacting behavior. Our experimental results show plausible interacting animations in that the user character performs a modified motion of user input and the counterpart character properly reacts against the user character. The proposed method will be useful for developing real-time interactive animation systems which provide a better immersive experience for users.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.6
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• pp.477-484
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• 2022

In this study, the cartridge part of the focused ultrasound stimulation system was used as a sample to conduct a skin irritation test and a skin sensitization test through animal experiments among the tests related to GLP (Good Laboratory Practice), a medical device safety evaluation standard. The test was conducted after IACUC approval using 6 female New Zeland White Rabbits. The polar and non-polar stimulation indices were all '0.0'. In addition, in the case of skin sensitization evaluation, 30 guinea pigs approved by IACUC were divided into control and experimental groups, and all induction and induction steps were applied using the eluate itself without separate dilution of the test sample and blank test solution. As a result of the experiment, the skin reaction grade of the control animal was 0 grade, and there was no animal showing more than 1 grade in the skin reaction of the test animal. As a result of both tests, no abnormal skin symptoms were observed, and when applied to the human body to treat patients, the test materials used in the tests will investigate the stability of whether any diseases that cause skin abnormal symptoms will occur.

• Imaging Science in Dentistry
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• v.52 no.3
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• pp.267-273
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• 2022

Purpose: The aim of this study was to assess the influence of kilovoltage- peak (kVp) and the metal artifact reduction (MAR) tool on the detection of buccal and lingual peri-implant dehiscence in the presence of titanium-zirconia (Ti-Zr) and zirconia (Zr) implants in cone-beam computed tomography (CBCT) images. Materials and Methods: Twenty implant sites were created in the posterior region of human mandibles, including control sites (without dehiscence) and experimental sites (with dehiscence). Individually, a Ti-Zr or Zr implant was placed in each implant site. CBCT scans were performed using a Picasso Trio device, with variation in the kVp setting (70 or 90 kVp) and whether the MAR tool was used. Three oral radiologists scored the detection of dehiscence using a 5-point scale. The area under the receiver operating characteristic (ROC) curve, sensitivity, and specificity were calculated and compared by multi-way analysis of variance (α=0.05). Results: The kVp, cortical plate involved (buccal or lingual cortices), and MAR did not influence any diagnostic values (P>0.05). The material of the implant did not influence the ROC curve values(P>0.05). In contrast, the sensitivity and specificity were statistically significantly influenced by the implant material (P<0.05) with Zr implants showing higher sensitivity values and lower specificity values than Ti-Zr implants. Conclusion: The detection of peri-implant dehiscence was not influenced by kVp, use of the MAR tool, or the cortical plate. Greater sensitivity and lower specificity were shown for the detection of peri-implant dehiscence in the presence of a Zr implant.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.54-63
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• 2022

This paper is a study on the friction damper, which is one of the seismic reinforcement devices for structures. This study developed a damper by replacing the internal friction material with ultra high molecular weight polyethylene (UHMWPE), a type of composite material. In addition, this study applied a multi-friction method in which the internal structure where frictional force is generated is laminated in several layers. To verify the performance of the developed multi-friction damper, this study performed a characteristic analysis test for the basic physical properties, wear characteristics, and disc springs of the material. As a result of the wear test, the mass reduction rate of UHMWPE was 0.003%, which showed the best performance among the friction materials based on composite materials. Regarding the disc spring, this study secured the design basic data from the finite element analysis and experimental test results. Moreover, to confirm the quality stability of the developed multi-friction damper, this study performed an seismic load test on the damping device and the friction force change according to the torque value. The quality performance test result showed a linear frictional force change according to the torque value adjustment. As a result of the seismic load test, the allowable error of the friction damper was less than 15%, which is the standard required by the design standards, so it satisfies the requirements for seismic reinforcement devices.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.3
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• pp.39-47
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• 2022

In this paper, we proposed a thickness measurement method of concrete slab using GPR, and the verification of the suggested algorithm was carried out through real-scale experiment. The thickness measurement algorithm developed in this study is to set the relative dielectric constant based on the unique shape of parabola, and time series data can be converted to thickness information. GPR scanning were conducted in four types of slab structure for noise reduction, including finishing mortar, autoclaved lightweight concrete, and noise damping layer. The thickness obtained by GPR was compared with Boring data, and the average error was 1.95 mm. In order to investigate the effect of finishing materials on the slab, additional three types of finishing materials were placed, and the following average error was 1.70 mm. In addition, sampling interval from device, the effect of radius on the shape of parabola, and Boring error were comprehensively discussed. Based on the experimental verification, GPR scanning and the suggested algorithm have a great potential that they can be applied to the thickness measurement of finishing mortar from concrete slab with high accuracy.