• Explosives and Blasting
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• v.42 no.3
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• pp.49-57
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• 2024

Pre-fracturing is the blasting method to weaken the rock mass prior to the main excavation. This study aims to evaluate the effectiveness of pre-fracturing by using half the explosive charge typically employed in conventional blasting designs. Field tests conducted at a quarry in Gapyeong showed that noise levels were reduced by 2.7 dB due to the decreased amount of explosive per blast hole, and vibration levels were controlled to the precision vibration control blasting standard. Rock weakening was confirmed through induced cracks observed on the surface and core samples, and it was noted that the weakening effect of the blasting decreased as the burden increased. The vibrations from conventional blasting were found to be lower than those from pre-fracturing. This was attributed more to the geological conditions, such as joints, rather than the blasting design factors like explosive amount, burden, and the number of free face.

• Korean Journal of Clinical Pharmacy
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• v.25 no.2
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• pp.61-67
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• 2015

Pharmacy education and training is continuously evolving to meet the requirement from the society in the UK. Most pharmacy schools offer the Master of pharmacy degree which is a four year undergraduate programme followed by a year of pre-registration placement spanning a year supervised by a professional pharmacist who has at least 3 years' post-registration experience; however, some universities provide either a 5-year sandwich course where the pre-registration training is split up into two periods of 6 months or a 2-year OSPAP programme for those who are already qualified as a pharmacist outside of the UK. The GPhC has announced that the format of the registration assessment is set to change in 2016. The exam questions from 2016 will be more clinical, practical and based around a patient in a real-life scenario. This article addresses important aspects of UK pharmacy education such as university curriculum, training programme, and licence exam, therefore, could potentially offer a significant contribution to the debate about raising academic standards of pharmacy education in South Korea.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.129-135
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• 2010

This paper suggests a multipath establishing scheme for ad hoc networks. Data paths are established by on-demand manner. Multipath are made as a sequence of route control message exchange at route setup process. Multipath can be used as a backup path or load balancing for data exchange. Proposed scheme uses a one-hop pre-search scheme for establishing multipath between source and destination. When a node selects a next node for route reply, the node finds optimal route by exchanging route information with neighbor nodes. Simulation results show that the proposed multipath scheme has better split characteristics among multipath and higher route survivability at the environment where nodes are moving.

• Journal of the Korean Society of Earth Science Education
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• v.5 no.3
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• pp.307-315
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• 2012

The purpose of this study was to examine the effects of small inquiry method on space perception ability and creative personality. Testees of this research are 36 elementary pre-service teachers taking an astronomical observation class. Doing inquiry activity after 36 elementary pre-service teachers are classified into 6 Jigsaw small inquiry. Learning activity was split into two groups, expert group and a population. To find out research outcome, pre-test was executed space perception ability test, creative personality test. Analysis of test result was accomplished with statistical package SPSS 18.0 paired t testing hypothesis. The results of this study are as follows. First, 'source of season change' class using Jigsaw small inquiry method has effect on space perception ability improvement. This was interpreted that space perception ability improvement was effective because characteristic of Jigsaw small inquiry is made up of lots of semin Second, 'source of season change' class using Jigsaw small inquiry method has no effect on creative personality. This was interpreted that experiment and discussion activity getting accomplished in a short time has no effect on qualitative characterizing Creative Personality improvement.

• Advances in concrete construction
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• v.11 no.3
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• pp.261-270
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• 2021

In this study, a new understanding is presented on the microcracking behavior of high strength concrete (HSC) with steel fiber addition having prior compressive loading history. Microcracking behavior at critical stress (σcr) region, using seven fiber addition volume of 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, and 2.0% was evaluated, at two aspect ratios (60 and 75). The specimens were loaded up to a specified compressive stress levels (0.70fc-0.96fc), and subsequently subjected to split tensile tests. This was followed by microscopic analyses afterwards. Four compressive stress levels as percentage of fc were selected according to the linearity end point based on stress-time (σ-t) diagram under uniaxial compression. It was seen that pre-compression has an effect on the linearity end point as well as fiber addition where it lies within 85-91% of fc. Tensile strength gain was observed in some cases with respect to the 'maiden' tensile strength as oppose to tensile strength loss due to the fiber addition with teething effect. Aggregate cracking was the dominant failure mode instead of bond cracks due to improved matrix quality. The presence of the steel fiber improved the extensive failure pattern of cracks where it changes from 'macrocracks' to a branched network of microcracks especially at higher fiber dosages. The applied pre-compression resulted in hardening effect, but the cracking process is similar to that in concrete without fiber addition.

• Advances in concrete construction
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• v.6 no.1
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• pp.47-68
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• 2018

This article reports the utilization of fly ash (FA) waste product from industry and silpozz which is an agro-waste from agriculture as an environmental friendly material in construction industry. The evaluation of strength and durability study was observed using FA and silpozz as a partial replacement of Ordinary Portland Cement (OPC). The studied parameters are compressive strength, flexural strength, split tensile strength and bond strength as well as the durability study involves the acid soluble chloride (ASC), water soluble chloride (WSC), water absorption and sorptivity. Scanning electron microscopy (SEM) and XRD of selected samples are also done. It reveals from the test results that the deterioration factor (DF) in compressive strength is 4% at 365 days. The DF of split tensile strength and flexural strength is 0.96% and 0.6% at 90 days respectively. The minimum slip is 1mm and 1.1mm after 28 days of testing bond strength for NWC and SWC sample respectively. The percentage decrease in bond strength is 10.35% for 28 days SWC samples. The pre-cast blended concrete samples performed better to chloride diffusion. Modulus of elasticity of SWC samples are also studied.The water absorption and sorptivity tests are conducted after 28 days of curing.

• Journal of Welding and Joining
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• v.32 no.2
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• pp.63-69
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• 2014

Dual laser heat sources were used for polymer based material joining. An infrared camera and thermocouple DAQ system were used to correlate the temperature distribution to computer simulation. A 50 degree tilted pre-heating laser source was acting as a heating source to promote the temperature to minimize thermal shock by the following a welding heat source. Based on the experimental result, the skin depth was empirically estimated for computer simulation. The offsets of 3mm, 5mm and 10mm split by weld and preheat were effectively used to control the temperature distribution for the optimal laser joining process. The closer offset resulted in an excessive melting or burning caused by sudden temperature rising. The laser power was split by 50%, 75% and 100% of the weld power, and the best results were found at 50% of preheating. To accurately simulate the physical laser beam absorption and joining optical properties were experimentally measured for the computer FEM simulation. The simulation results showed close correlation between theoretical and experimental results. The developed dual laser process is expected to increase productivity and minimize the cost for the final products.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.8
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• pp.79-86
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• 1999

A simulation of 10 Gbps optical fiber transmission system using DCf(dispersion compensating fiber) for the dispersion compensation is performed. In order to analyze the NRZ pulse propagation in nonlinear, dispersive and lossy fiber, the split-step finite element method that is combination of finite element method and finite difference method is used. Also, we obtained the optical eye diagram and BER characteristics at the receiver of the system that is contained the optical amplifier and system noises. As a result of simulation, we obtain that the dispersion penalty is about 0.8dB after 50km transmission and the receiver sensitivities at $10^{-9}$ BER are -27.4dBm with EDFA pre-amplifier of 12dB gain and -15.6dBm without EDFA.

• Journal of IKEEE
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• v.25 no.1
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• pp.10-14
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• 2021

This paper presents a hardware that improves the complexity of the CIE1931 color coordinate algorithm operation. The conventional algorithm has disadvantage of growing hardware due to 4-Split Multiply operations used to calculate large bits in the computation process. But the proposed algorithm pre-calculates the defined R2X, X2R Matrix operations of the conventional algorithm and makes them a matrix. By applying the matrix to the images and improving the color, it is possible to reduce the amount of computation and hardware size. By comparing the results of Xilinx synthesis of hardware designed with Verilog, we can check the performance for real-time processing in 4K environments with reduced hardware resources. Furthermore, this paper validates the hardware mount behavior by presenting the execution results of the FPGA board.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.3
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• pp.218-224
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• 2011

Purpose: The purpose of this study is to evaluate the post-operative skeletal stability after surgical correction of patients with mandibular prognathism by bilateral sagittal split ramus osteotomy (BSSRO) and to evaluate the horizontal relapse tendency after the surgery. Methods: Twenty-six patients with Class III dental and skeletal malocclusion were selected for this retrospective study. Fifteen of them underwent BSSRO for mandibular setback and eleven of them underwent two-jaw surgery (Lefort I and BSSRO). In each patient, lateral cephalometric radiographs were taken pre-operatively, post-operatively within 1 week, and post-operatively after eight months. After tracing of the cephalometric radiographs, various parameters were measured. The analyses were done by linear measurement to evaluate the change in position of hard tissue B point, pogonion and mandibular plan angle by examination on lateral cephalograms. Results: The horizontal relapse rate was 27.1% at B point and 31.6% at pogonion in patients who underwent BSSRO. The horizontal relapse rate of the group where the amount of correction exceeded 10 mm was 25.69% at B point. Conclusion: There were no statistical differences on the magnitude of setback and direction of rotation of the mandible in mandibular stability. There were also no statistical differences between single mandibular surgery and two-jaw surgery for mandibular stability.