Image reconstruction algorithm for momentum dependent muon scattering tomography

Bae JungHyun,Montgomery Rose,Chatzidakis Stylianos 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.5

Nondestructive radiography using cosmic ray muons has been used for decades to monitor nuclear reactor and spent nuclear fuel storage. Because nuclear fuel assemblies are highly dense and large, typical radiation probes such as x-rays cannot penetrate these target imaging objects. Although cosmic ray muons are highly penetrative for nuclear fuels as a result of their relatively high energy, the wide application of muon tomography is limited because of naturally low cosmic ray muon flux. This work presents a new image reconstruction algorithm to maximize the utility of cosmic ray muon in tomography applications. Muon momentum information is used to improve imaging resolution, as well as muon scattering angle. In this work, a new convolution was introduced known as M-value, which is a mathematical integration of two measured quantities: scattering angle and momentum. It captures the objects’ quantity and density in a way that is easy to use with image reconstruction algorithms. The results demonstrate how to reconstruct images when muon momentum measurements are included in a typical muon scattering tomography algorithm. Using M-value improves muon tomography image resolution by replacing the scattering angle value without increasing computation costs. This new algorithm is projected to be a standard nondestructive radiography technique for spent nuclear fuel and nuclear material management.

Characteristics of pellet-type adsorbents prepared from water treatment sludge and their effect on trimethylamine removal

Junghyun Bae,전종기,Nayoung Park,Goun Kim,이철호,Young Kwon Park 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.4

We optimized the preparation method of pellet-type adsorbents based on alum sludge with the aim of developinga high-performance material for the adsorption of gaseous trimethylamine. Effects of calcination temperatureon physical and chemical properties of pellet-type adsorbents were investigated. The porous structure and surfacecharacteristics of the adsorbents were studied using N2 adsorption and desorption isotherms, scanning electron microscope,X-ray diffraction, temperature-programmed desorption of ammonia, and infrared spectroscopy of adsorbed pyridine. The adsorbents obtained from the water treatment sludge are microporous materials with well-developed mesoporosity. The pellet-type adsorbent calcined at 500 oC had the highest percentage of micropore volume and the smallestaverage pore diameter. The highest adsorption capacity in trimethylamine removal attained over the pellet-type adsorbentcalcined at 500 oC can be attributed to the highest number of acid sites as well as the well-developed microporosity.

6자유도 로봇 매니퓰레이터에 대한 비선형 type- 외란 관측기 기반 강인 제어

배정현(Junghyun Bae),박원영(Wonyoung Park),변순석(Sunseok Byeon),박경훈(Gyunghoon Park) 대한전자공학회 2021 대한전자공학회 학술대회 Vol.2021 No.11

CMOS Power Amplifier Integrated Circuit With Dual-Mode Supply Modulator for Mobile Terminals

Junghyun Ham,Jongseok Bae,Hyungchul Kim,Mincheol Seo,Hwiseob Lee,Keum Cheol Hwang,Kang-Yoon Lee,Cheon-seok Park,Deukhyoun Heo,Youngoo Yang IEEE 2016 IEEE Transactions on Circuits and Systems I: Regul Vol.63 No.1

<P>A CMOS power amplifier integrated circuit with an optimized dual-mode supply modulator is presented. The dual-mode supplymodulator, based on a hybrid buck converter consisting of a wideband linear amplifier and a highly efficient switching amplifier, provides two operation modes: envelope tracking (ET) for high average output power and average power tracking (APT) for low output power. For the APT mode, the linear amplifier is switched off and the switching amplifier operates as a normal buck converter to supply DC voltage to the power amplifier according to the average output power. The optimum switch sizes of the switching amplifier were analyzed and applied for each operation mode for higher efficiency. An integrated circuit with a power amplifier and the dual-mode supply modulator was designed and fabricated using a 0.18-mu m CMOS process for LTE applications at a frequency of 0.78 GHz. For the 16-QAM uplink LTE signal, the measured efficiency with an ET mode is as high as 45.4%, which is 7.0% higher than that from the stand-alone power amplifier at an average output power of 24 dBm. An efficiency of 14.1% was achieved with an APT mode at an average output power of 9 dBm. This is 3.2% higher than that with the ET mode.</P>

Experimental investigation of passive thermodynamic vent system (TVS) with liquid nitrogen

Bae, Junhyuk,Yoo, Junghyun,Jin, Lingxue,Jeong, Sangkwon Elsevier 2018 Cryogenics Vol.89 No.-

<P>Thermodynamic vent system (TVS) is an attractive technology to maintain an allowable pressure level of a cryogenic propellant storage in a spacecraft under micro-gravity condition. There are two types of TVS; active or passive. In this paper, the passive TVS which does not utilize a cryogenic liquid circulation pump is experimentally investigated with liquid nitrogen and numerically analyzed by thermodynamic and heat transfer model. A cylindrical copper tank, which is 198 mm in inner diameter and 216 mm in height, is utilized to suppress a thermal-stratification effect of inside cryogenic fluid. A coil heat exchanger, which is 3 m in length and 6.35 mm in outer diameter, and a fixed size orifice of which diameter is 0.4 mm are fabricated to remove heat from the stored fluid to the vented flow. Each vent process is initiated at 140 kPa and ended at 120 kPa with liquid nitrogen fill levels which are 30%, 50% and 70%, respectively. In the numerical model, the fluid in the tank is assumed to be homogeneous saturated liquid-vapor. Mass and energy balance equations with heat transfer conditions suggested in this research are considered to calculate the transient pressure variation in the tank and the amount of heat transfer across the heat exchanger. We achieve the average heat rejection rate of more than 9 W by TVS and conclude that the passive TVS operates satisfactorily. In addition, the prediction model is verified by experimental results. Although the model has limitation in providing accurate results, it can surely predict the tendency of pressure and temperature changes in the tank. Furthermore, the model can suggest how we can improve the heat exchanger design to enhance an overall efficiency of passive TVS. Moreover, the performance of passive TVS is compared with other cryogenic vent systems (direct vent system and active TVS) by suggested performance indicator.</P>

Dual Bias Modulator for Envelope Tracking and Average Power Tracking Modes for CMOS Power Amplifier

Junghyun Ham,Haeryun Jung,Jongsuk Bae,Wonseob Lim,Keum Cheol Hwang,Kang-Yoon Lee,Cheon-Seok Park,Youngoo Yang 대한전자공학회 2014 Journal of semiconductor technology and science Vol.14 No.6

This paper presents a dual-mode bias modulator (BM) for complementary metal oxide semiconductor (CMOS) power amplifiers (PAs). The BM includes a hybrid buck converter and a normal buck converter for an envelope tracking (ET) mode for high output power and for an average power tracking (APT) mode for low output power, respectively. The dual-mode BM and CMOS PA are designed using a 0.18-㎜ CMOS process for the 1.75 ㎓ band. For the 16-QAM LTE signal with a peakto-average power ratio of 7.3 ㏈ and a bandwidth of 5 ㎒, the PA with the ET mode exhibited a poweradded efficiency (PAE) of 39.2%, an EVM of 4.8%, a gain of 19.0 ㏈, and an adjacent channel leakage power ratio of -30 ㏈c at an average output power of 22 ㏈m, while the stand-alone PA has a PAE of 8% lower at the same condition. The PA with APT mode has a PAE of 21.3%, which is an improvement of 13.4% from that of the stand-alone PA at an output power of 13 ㏈m.

Effects of a low-FODMAP enteral formula on diarrhea on patients in the intensive care unit

Eunjoo Bae,Jiyoon Kim,Jinyoung Jang,Junghyun Kim,Suyeon Kim,Youngeun Chang,MI YEON KIM,Mira Jeon,Seongsuk Kang,Jung Keun Lee,Tae Gon Kim 한국영양학회 2021 Nutrition Research and Practice Vol.15 No.6

BACKGROUND/OBJECTIVES: A dietary restriction on the intake of fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) has been reported to be effective in the treatment of gastrointestinal (GI) tract complications. Enteral nutrition (EN) is widely used for patients who cannot obtain their nutritional requirements orally, but many studies have reported EN complications, especially diarrhea, in up to 50% of patients. SUBJECTS/METHODS: We performed a single-center, non-randomized, controlled trial to determine the effects of a low-FODMAP enteral formula on GI complications in patients in intensive care units (ICUs). Patients in the ICU who needed EN (n = 66) were alternately assigned to the low-FODMAP group (n = 33) or the high-FODMAP group (n = 33). RESULTS: Anthropometric and biochemical parameters were measured, and stool assessment was performed using King"s Stool Chart. We excluded patients who received laxatives, GI motility agents, proton pump inhibitors, antifungal agents, and antibiotics other than β-lactams. There were no differences in GI symptoms during 7 days of intervention, including bowel sound, abdominal distension, and vomiting between the 2 groups. However, diarrhea was more frequent in the high-FODMAP group (7/33 patients) than the low- FODMAP group (1/33 patients) (P = 0.044). CONCLUSIONS: Our results suggest that a low-FODMAP enteral formula may be a practical therapeutic approach for patients who exhibit enteral formula complications. Our study warrants further randomized clinical trials and multicenter trials.

다층구조방정식을 활용한 단위학교 교사학습공동체의 학업성취 효과 분석

배정현(Junghyun,Bae),유성상(Sung-Sang Yoo) 한국교육사회학회 2022 교육사회학연구 Vol.32 No.2

본 연구는 단위학교 교사학습공동체가 경기도 지역 중학생의 학업성취에 효과적인지 확인하는 것을 목적으로 한다. 특히, 효과의 경로를 함께 밝힘으로써 교사학습공동체의 발달이 교육과정에 미치는 영향력을 입증하여 학업성취 효과의 타당성을 높이고자 한다. 이를 위해서 경기교육종단연구(GEPS) 4차년도 자료와 6차년도 자료를 활용하여 다층구조방정식(MSEM) 통계 분석을 실시하였다. 변인 구성에 있어서 학생성취에 대한 교사학습공동체의 영향력이 공동체의 질적 수준에 따라서 달라질 것이라 보고 교사학습공동체 발달 수준이라는 학교수준 교육과정 변인을 구성하였다. 다음으로 학생수준 교육과정 변인은 학습자 중심 수업과 교사 수업 능력, 학생수준 교육결과 변인은 3년 간 국어, 영어, 수학 과목의 수직척도 점수로 산출한 성장점수를 활용하였다. 분석 결과, 첫째, 단위학교 교사학습공동체가 발달할수록 학생은 국어, 영어, 수학 수업에서 학습자 중심 수업이 이루어진다고 인식하였고 이는 학생이 교사의 수업 능력을 긍정하는데도 영향을 미쳤다. 둘째, 교사학습공동체 발달에 따른 학생 학업성취 효과는 영어 과목에서만 확인되었다. 이를 통해 단위학교의 교사학습공동체 발달은 국어, 영어, 수학 과목의 학습자 중심 수업을 촉진시키면서 해당 과목의 수업을 개선시켰고 영어 과목에만 한정하여 학업성취 효과가 나타났다. 이를 통해 교사학습공동체는 효과적인 학교를 결정짓는 중요한 요인으로 확인됨으로써 단위학교의 교육력을 높이기 위한 방안으로 높은 질적 수준이 담보된 공동체 중심의 학습 조직이 촉진되어야 함을 시사한다. The purpose of the study is to reveal the effects of School-based Professional Learning Communities(PLCs) on middle school teachers and students of Gyeonggi-do using the Multilevel Structural Equation Modeling. For this purpose, this study tried to find the possibility of PLCs as a factor in determining effective schools by revealing the paths of effectiveness in the processes of schooling. . To this end, statistical analysis of multi-layer structural equations (MSEM) were performed using data from the 4th and 6th years of the Gyeonggi Education Panel Study(GEPS). This article confirmed the effect of PLCs influencing Student Academic Achievements and established the Path Analysis. The findings are as follows. First, the effect of PLCs' Student Academic Achievements was confirmed only in English subjects. Second, as a result of confirming the effect of school-level PLCs on only English achievement. However it was found that as PLCs develop, it promotes learner-centered classes and contributes to improving the quality of classes on all achievements. In summary, school-level PLCs were playing a role in determining effective schools that contributed to student achievement partially while improving school classes with learner-centered classes.

A Programmable Impedance Tuner With Finite SWRs for Load-Pull Measurement of Handset Power Amplifiers

Younghwan Bae,Unha Kim,Junghyun Kim THE INSTITUTE OF ELECTRICAL ENGINEERS 2015 IEEE Microwave and Wireless Components Letters Vol. No.

<P>A novel coupler/reflection-type electronic impedance tuner is proposed with quantitative analysis. The tuner is divided into a magnitude part and a phase part, and the magnitude and phase of the tuner impedance can be controlled separately just with one design parameter, respectively, thus facilitating programmable control for constant magnitude and uniform phase distribution. The tuner with standing wave ratio (SWR) = 2.5 and 6 was implemented for 3G/4G handset low-band transmitter (Tx) power amplifier (PA) load-pull measurement. The fabricated tuner showed very uniform reflection coefficient distribution with magnitude deviations of less than 0.05/0.08 at SWR = 2.5 / 6 and phase deviations of less than 5 <SUP>°</SUP>. PA load-pull measurement result using the tuner showed good agreement with a mechanical tuner, thus verifying the practical usefulness of the proposed tuner.</P>

Archaeological Survey of the Gilan Province, Iran

Kidong BAE,Inkyung CHANG,Hanyoung LEE,Chulmin LEE,Jinsung KIM,Semi CHUNG,Junghyun YOON 한국구석기학회 2009 한국구석기학회 학술대회 발표집 Vol.2009 No.1