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This study focusses on investigating the effect of flow orientation on global and local two-phase flow parameters under two-phase flow conditions. Flow visualization, pressure measurement, and conductivity probe measurements are performed in a test facility made of 50.8 mm inner diameter acrylic pipes with flow visualization, pressure measurement, and conductivity probe measurement. Characteristics of flow regimes and interfacial structures, and frictional pressure drop prediction in the vertical upward and vertical downward two-phase flows are compared and analyzed. The results show that unique coring phenomenon and slug bubbles with off-centered noses appear in the vertical downward flow. The flow regime transition boundaries shift to the lower gas superficial velocities in the vertical downward flow compared to that in the vertical upward flow. Furthermore, the distribution and one-dimensional transport of the void fraction, interfacial area concentration, bubble velocity, bubble Sauter-mean diameter, and bubble frequency are acquired and compared to study the effect of flow orientation on interfacial structures. The interfacial structure and its development are found to be mainly affected by the lift force and the turbulence related bubble interactions. The frictional pressure drop is acquired and modeled by the Lockhart–Martinelli correlation. The frictional pressure drop is found to be larger in the vertical upward flow than that in the vertical downward flow. The recommended C value for both vertical upward and vertical downward flows are proposed.

This article presents a fully integrated stand-alone narrowband Internet-of-Things (NB-IoT) and global navigation satellite system (GNSS) system-on-chip (SoC). It aims for an all-in-one system to integrate all necessary blocks such as an RF transceiver, a power management system (PMIP), and a clock management system and to save a bills-of-material (BOM) cost. An RF transceiver is integrated to support multi-band cellular IoT and GNSS with a CMOS RF power amplifier transmitting 23-dBm output power. A PMIP, including bucks, a boost, and low-dropout regulators (LDOs), is integrated to support coin cell or AAA battery and to support a wide input supply voltage range from 2.5 to 5 V. In addition, clock management system is embedded with a digitally controlled crystal oscillator (DCXO), a relaxation oscillator (RCO), and temperature sensor units (TSUs). It is fabricated in a standard 28-nm CMOS process and its size is 24.6 mm2. The power consumption of always-on-block is 15 $\mu \text{W}$ , and the sleep current consumption is less than 10 $\mu \text{A}$ at 3.8 V.

This paper presents a non-inverting buck–boost converter for high-voltage automotive applications. The converter includes a newly proposed controller chip and four off-chip NMOS power transistors with two bootstrap capacitors. Conventional non-inverting buck–boost converters have two operation modes: the buck and boost modes. This study implements four operation modes for smooth transition between these modes. In converters with four operation modes, non-switching high-side power transistors require continuous high gate-driving voltages without the bootstrapping operation. The designed non-inverting buck–boost converter drives non-switching high-side NMOS transistors through the proposed bootstrap-sharing technique. A new current sensing technique is also proposed that works reliably under high-voltage operating conditions. This current sensing enables the converter’s modulation scheme of the current programmed control. The proposed converter was fabricated using a $0.18~\mu \text{m}$ BCD 1P4M process. The total chip area is $2.50\times 2.50\,\,mm^{2}$ , including the bonding pads. The output voltage range is from 1.05 to 60 V, with a typical input automotive battery voltage of 14 V. Because the automotive battery exhibit a wide voltage fluctuation, the input voltage range is designed from 7 to 60 V. Its switching frequency range is from 600 to 1000 kHz and the maximum power efficiency is 96.1% at a load current of 1.5 A.

Although cellular secretion is important in industrial biotechnology, its assessment is difficult due to the lack of efficient analytical methods. This study describes a synthetic cellular communication-based microfluidic platform for screening strains with the improved secretion of 3-hydroxypropionic acid (3-HP), an industry-relevant platform chemical. 3-HP-secreting cells were compartmentalized in droplets, with receiving cells equipped with a genetic circuit that converts the 3-HP secretion level into an easily detectable signal. This platform was applied to identify Escherichia coli genes that enhance the secretion of 3-HP. As a result, two genes (setA, encoding a sugar exporter, and yjcO, encoding a Sel1 repeat-containing protein) found by this platform enhance the secretion of 3-HP and its production. Given the increasing design capability for chemical-detecting cells, this platform has considerable potential in identifying efflux pumps for not only 3-HP but also many important chemicals.

The current work performs air-water experiments in three different pipe sizes of 38 mm, 51mm, and 102 mm to investigate the frequencies of plug and slug bubbles in horizontal flows. The local four-sensor conductivity probe is used to establish experimental data for large elongated bubbles. The investigated conditions focus on a relatively high superficial liquid velocity region (1.0 m/s ≤ jf ≤ 4.0 m/s), where limited experimental data are available in the literature. The investigated superficial gas velocity (jg) ranges from 0.19 m/s to 3.0 m/s. In total, 19 conditions are studied. To identify the elongated plugs and slugs, the local four-sensor conductivity probe is located near the top wall. Based on the flow visualization study, the stable plug and slug bubbles cannot be shorter than a pipe diameter. Therefore, a chord length greater than a pipe size is used as a criterion to pick up the elongated plug and slug bubbles. Using the obtained data, the frequencies of plug and slug bubbles are analyzed. For the investigated conditions, the Strouhal number (St) ranges from 0.03 to 1.68, while the St of the existing data in the literature are generally below 0.1. It is found that the frequency of elongated bubbles increases as jf increases, but first increases then decreases as jg increases. This indicates that large elongated bubbles start to coalesce once jg reaches a certain value. This threshold has a higher value of jg than the plug to slug transition point. In addition, the frequency decreases as pipe size increases. The existing correlations in the literature are evaluated using the newly collected data. It is found that the St number-based correlations can predict the data with higher accuracy. New correlations are developed using the new data and they can predict the frequency with an absolute average percentage difference of ±20%.

The current work investigates the thermal-hydraulics of the fast core of a HYbrid fast/thermal core configuration Subcritical Testbed (HYST), a new concept for irradiation experiments in fast-reactor-like environment. The Reynolds-Averaged Navier Stokes (RANS) simulations using ANSYS Fluent are performed. A benchmark study is first performed to validate the simulation of liquid LBE flow in a wire-wrapped rod bundle geometry using the experimental data in Pacio et al. (2016), which provides the most detailed data for rod surface temperature, LBE temperature in the subchannel, and pressure drop along the test section. Two turbulence models (Standard k-ε model with Standard Wall Function and Realizable k-ε model with Enhanced Wall Treatment), two approaches to simplify the wire-rod contact and different models for turbulent Prandtl number (Prt) are tested. It is found that the selected models can predict the data well and are therefore used for simulations of the LBE loop in HYST. A mesh independence study is performed in simulating the LBE loop in HYST with three different meshes being generated (number of cells: 14.8 million, 25.8 million, and 45.4 million). It is found that the mesh independency is reached using the mesh with 25.8 million cells. The effect of non-uniform power distribution in the radial direction of the core is investigated. It is found that the temperature profiles change significantly when uniform power distribution changes to non-uniform. An experimental facility is being constructed and newly collected data will be used to evaluate the RANS simulations. Once validated, the current model will be valuable for the design, licensing, and operation of the HYST prototype.

본 연구의 목적은 유아 리더십교육에 관한 최근 연구동향을 분석하여, 유아 리더십교육의 방향을 모색하는데 있다. 이를 위해 2004년부터 2018년까지 한국연구재단 등재지에 발표된 279편의 논문들을 5년씩 3주기로 구분하였고, 연구주제, 연구유형, 연구대상, 자료수집방법 등의 기준으로 분석하였다. 분석결과를 살펴보면, 첫째 연구주제로 유아 리더십의 영향 관계를 살펴본 연구가 가장 활발히 진행되었다. 둘째, 3기(2014-2018)로 갈수록 유아 리더십의 영향 관계와 프로그램 개발 및 효과에 관한 연구만이 증가하였다. 셋째, 가장 많이 사용된 연구유형은 양적연구, 연구대상은 만 5세 유아, 자료수집방법은 질문지법인 것으로 나타났다. 넷째, 국내 학술 논문과 학위 논문 간의 차이는 연구대상과 자료수집방법측면에서 차이가 있는 것으로 나타났다. 본 연구결과에 근거하여 유아 리더십 교육 연구활성화를 위하여 유아 리더십과 관련된 질적연구, 비교 문화 연구, 연구 대상을 부모 및 교사로 확대한 연구, 기초연구로서 내용분석법과 면담법을 활용한 연구들의 필요성을 제언하는 바이다.

We determined the effects of ex situ biological wastewater treatment on landfill stabilization under continuous circulation of leachate. Specifically, the waste composition and nitrogen in the leachate during leachate circulation (LC) alone was compared with that in a nitrified leachate circulation (NLC) system. An ex situ sequencing batch reactor (SBR) was applied in the NLC system to oxidize the ammonium to nitrite or nitrate, which was then circulated to landfill for denitrification to nitrogen gas. The chemical oxygen demand (COD) concentration in the leachate was low by NLC versus LC, because in the NLC system, ammonium was oxidized to nitrite/nitrate in the ex situ SBR, and aerobic decomposition and denitrification occurred simultaneously in the landfill, suggesting that the NLC system significantly improves the waste decomposition rate and accelerates landfill stabilization. Because denitrification in the landfill was activated in the NLC system and nitrite/nitrate was reduced to nitrogen gas, the proportion of nitrogen in the gas was higher compared with LC. LC, combined with an SBR, might have value in removing the nitrogen that is discharged from the leachate and in accelerating landfill stabilization, because landfill waste was used as the carbon source for denitrification.

The shortcut biological nitrogen removal (SBNR) process requires less aeration and external carbon due to the oxidization of ammonia into nitrite and its direct denitrification to nitrogen gas during the biological nitrogen removal process. However, this process produces a poor effluent containing NH4+, since the system has to maintain a high free ammonia (FA, NH3) concentration. To overcome this drawback, in this study, the solid retention time (SRT) and the dissolved oxygen (DO) concentration were controlled to achieve both a high ammonia removal rate and nitrite accumulation in the sequencing batch reactor (SBR) process, which can remove nitrogen from wastewater to the desired concentration and provide high free ammonia inhibition and continuous shock loading. When sufficient DO was supplied, nitrite did not accumulate with a 20-day SRT, but the wash-out of nitrite oxidizers in a shorter SRT resulted in a high nitrite accumulation. When DO acted as a limitation, nitrite accumulated at all SRTs. This indicates that nitrite accumulation is more highly influenced by SRT and DO concentration than by FA inhibition. Also, as nitrite accumulated over a 10-day SRT regardless of DO concentration, the accumulation was more highly influenced by SRT than by DO concentration.

The current work develops a robust image analysis technique for quantitative measurements in horizontal plug flow. To do this, experiments are performed to capture high-speed videos for horizontal air-water plug flow for two test conditions in a 38.1 mm ID pipe. A visualization block-mirror system is designed and fabricated to allow the simultaneous visualization of two-phase flow from both top and side views using a single camera. To obtain images of high quality for analysis, the angle and position of the camera relative to the visualization block are verified. With the obtained images, an algorithm is developed to detect and track the interface of plug bubbles. Due to the existence of contacting or overlapping small bubbles, additional algorithms are developed to segment the interfaces of plug bubble from those of small bubbles, including distance checking, interface breakpoints detection, and convex curvature segmentation. As a result, the nose position, local time-averaged axial velocity, and area-averaged time-averaged void fraction for plug bubbles can be obtained with this newly developed image analysis technique. To benchmark the newly developed image analysis code, local four-sensor conductivity probe measurements are performed. The axial velocity for plug bubbles generally agrees within ±10% between image analysis technique and the four-sensor conductivity probe measurement technique, while the plug bubble reconstruction approach can generate an area-averaged void fraction within ±10% of the probe measured value.

This is a retrospective cohort study using notification data in South Korea. We evaluated the nationwide status, regional differences, and the determinants of treatment outcomes among tuberculosis patients. Treatment success rate improved from 77.0% in 2012 to 86.0% in 2015. The lost to follow-up rate was higher among older people, males, and foreign nationals. Health care facilities designated for the Public-Private Mix (PPM) project showed higher success rate and lower rate of lost to follow-up. Moreover, municipalities with low regional deprivation index had higher PPM project coverage. Since there is a large regional difference in the coverage of the PPM project, an additional community-based support program should be implemented, especially for tuberculosis patients residing in region with low PPM project coverage.

Cold atom quantum sensors based on atom interferometry are among the most accurate instruments used in fundamental physics, metrology, and foreseen for autonomous inertial navigation. However, they typically have optically complex, cumbersome, and low-bandwidth atom detection systems, limiting their practical applications. Here, we demonstrate an enabling technology for high-bandwidth, compact, and nondestructive detection of cold atoms, using microwave radiation. We measure the reflected microwave signal to coherently and distinctly detect the population of single quantum states with a bandwidth close to 30 kHz and a design destructivity that we set to 0.04%. We use a horn antenna and free-falling molasses cooled atoms in order to demonstrate the feasibility of this technique in conventional cold atom interferometers. This technology, combined with coplanar waveguides used as microwave sources, provides a basic design building block for detection in future atom chip-based compact quantum inertial sensors. The use of cold atom interferometry for applications in metrology and accurate instrumentation is hampered by optically cumbersome atom detection systems. The authors present a non-destructive microwave detection method for the quantum states of cold atoms that overcomes the need for complex optical systems and experimental set ups, making it a more portable solution for quantum and inertial sensing.

Supplemental material, sj-pdf-1-aph-10.1177_10105395211000529 for Status and Determinants of Treatment Outcomes Among New Tuberculosis Patients in South Korea: A Retrospective Cohort Study by Hyunjin Son, Jeongha Mok, Miyoung Lee, Wonseo Park, Seungjin Kim, Joosun Lee, Bo Youl Choi and Changhoon Kim in Asia Pacific Journal of Public Health