Blast Hole Pressure Measurement and a Full-Scale Blasting Experiment in Hard Rock Quarry Mine Using Shock-Reactive Stemming Materials

By increasing the effectiveness of the energy generated by the explosive charge inserted into a blast hole, stemming increases rock fragmentation. Missing or improper stemming, which can lead to the detonation gas escaping from the blast hole in advance, results not only in the waste of explosive energy and poor fragmentation but also in environmental problems, such as ground vibration, noise, flying rocks, back breaks, and air blasts. In this study, a stemming material based on a shear thickening fluid (STF) that reacts to dynamic pressure was developed. Two blasting experiments were conducted to verify the performance of the STF-based stemming material. In the first experiment, the pressure inside the blast hole was directly measured based on the application of the stemming material. In the second experiment, full-scale bench blasting was performed, and the blasting results of sand stemming and the STF-based stemming cases were compared. The measurement results of the pressure in the blast hole showed that when the STF-based stemming material was applied, the pressure at the top of the blast hole was lower than in the sand stemming case, and the stemming ejection was also lower. Full-scale bench blasting was conducted to compare the two types of stemming materials by evaluating the size of the rock fragments using image processing. The results of the two blasting experiments helped to verify that the blockage performance of the STF-based stemming material in the blast hole was superior to that of the sand stemming material

A Referenceless Digital CDR with a Half-Rate Jitter-Tolerant FD and a Multi-Bit Decimator

A referenceless digital clock and data recovery (D-CDR) circuit using a half-rate jitter-tolerant frequency detector (FD) and a multi-bit decimator is presented. For a referenceless configuration, we introduced a half-rate jitter-tolerant digital quadricorrelator frequency detector (JT-DQFD). Additionally, we proposed a multi-bit decimator circuit that losslessly down-samples up/down data from a phase detector to reduce the recovered clock jitter. The down-sampled multi-bit phase information is processed by a digital loop filter to adjust the phase of the recovered clock. Fabricated in a 28-nm CMOS technology, the test chip achieves a power efficiency of 1.3 pJ/bit at 10 Gb/s

Effects of interfacial area and energetic barrier on thermoelectric performance of PEDOT:PSS–MXene composite films

Thermoelectric (TE) devices based on conducting polymers have significant potential for low-temperature energy harvesting. To enhance the TE performance, the incorporation of low-dimensional inorganic fillers into the polymer matrix has been considered as a promising strategy by exploiting the energy filtering effect. Since the energy filtering effect is strongly influenced by the carrier scattering at the interface between polymer and inorganic fillers, the TE properties are likely to be affected by the interfacial properties of two constituents. In this study, we investigated the TE performance in the composite films of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and two-dimensional Ti _3 C _2 MXene, in order to reveal the effects of the interfacial area and the energetic barrier on the TE performance by controlling the MXene sizes and the oxidation level of PEDOT:PSS. We found that the composite film with smaller MXene exhibits a higher power factor ( PF) than that with larger MXene, originating from the increased interfacial area which facilitates the energy filtering effect. We also showed that an optimal energy barrier (0.14 eV) between PEDOT:PSS and MXene can accelerate the energy filtering effect, which allows to maximize the PF of the composite films up to 69.4 μ W m ^−1 K ^−2 . We believe that our study not only contributes to the development of the composite-based TE devices utilizing the energy filtering effect, but also helps to understand the charge transport in polymer–inorganic composites

Origin of the Mixing Ratio Dependence of Power Conversion Efficiency in Bulk Heterojunction Organic Solar Cells with Low Donor Concentration

We studied the origin of the improvement in device performance of thermally evaporated bulk heterojunction organic photovoltaic devices (OPVs) with low donor concentration. Samples with three different donor-acceptor mixing ratios, 0:10 (C70-only), 1:9 (low-doped) and 3:7 (high-doped), were fabricated with 1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)-cyclohexane (TAPC):C70. The power conversion efficiencies (PCEs) of these samples were 1.14%, 2.74% and 0.69%, respectively. To determine why the low-doped device showed a high PCE, we measured various properties of the devices in terms of the effective energy band gap, activation energy, charge carrier mobility and recombination loss. We found that the activation energy for charge carrier transport was increased as we increased the TAPC concentration in the blends whereas the hole and electron mobilities became more balanced as the TAPC concentration was increased. Furthermore, the recombination loss parameter alpha (from the light intensity dependence) remained alpha to approximately 0.9 in the low-doped device, but it decreased to alpha to approximately 0.77 in the high-doped device, indicating a large recombination loss as a result of space charge. Therefore, the improved PCE of low-doped OPVs can be attributed to the balance between carrier mobilities with no increase in recombination loss.This work was supported by the Human Resources Development Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 20124010203170).OAIID:oai:osos.snu.ac.kr:snu2013-01/102/0000029430/6SEQ:6PERF_CD:SNU2013-01EVAL_ITEM_CD:102USER_ID:0000029430ADJUST_YN:NEMP_ID:A076109DEPT_CD:430CITE_RATE:1.149FILENAME:journal of nanoscience and nanotechnology 13, 7982 (dec, 2013).pdfDEPT_NM:전기·정보공학부EMAIL:[email protected]_YN:YCONFIRM:

Effects of hormone therapy on the clinical outcomes of endoscopic intervention in patients with endometriosis-related ureteral obstruction

Purpose: We investigated whether endoscopic interventions, including laser endoureterotomy and balloon dilatation following hormone therapy, are a good choice to treat ureteral obstruction due to ureteral endometriosis instead of laparoscopic or open surgery. Materials and Methods: Patients with ureteral obstruction due to endometriosis who underwent endoscopic intervention between 2004 and 2021 were reviewed. Patients with other causes of ureteral obstruction or previous ureteral surgery were excluded from the study. The primary endpoint was the 3-month success rate of endoscopic intervention with or without hormone therapy. Secondary endpoints were the success rate of endoscopic intervention between the hormone-treated and hormone-untreated groups at 6 months and the success rate according to the hormone therapy response of endometriosis at 3 and 6 months. Results: Eighteen patients with 19 ureter units were evaluated in this study, including 12 patients receiving hormone therapy and six patients not receiving hormone therapy. Among patients receiving hormone therapy, one patient had bilateral ureteral obstruction. The success rate of endoscopic intervention was higher in patients who received hormone therapy than in those who did not receive hormone therapy three months after endoscopic intervention (76.9% vs. 0.0%, p=0.003). The same result was also found 6 months after endoscopic intervention (75.0% vs. 0.0%, p=0.005). In addition, the success rates were higher in the hormone-responsive group than in the non-responsive group (100.0% vs. 57.1%), although the difference was not statistically significant (p=0.122). Conclusions: Ureteral obstruction caused by endometriosis can be effectively treated by endoscopic intervention with hormone therapy in select patients