Orbit Determination of Korea Regional Navigation Satellite System Using Inter-Satellite Links and Ground Observations

Jungmin Choi,Hyungjik Oh,Chandeok Park,Sang-Young Park 한국항공우주학회 2017 International Journal of Aeronautical and Space Sc Vol.18 No.2

This study presents the orbit determination (OD) of a candidate Korea Regional Navigation Satellite System (KRNSS) using both inter-satellite links (ISLs) and ground observations. The candidate constellation of KRNSS is first introduced. The OD algorithm based on both ISL and ground observation is developed, and consists of three main components: dynamic model for Korean navigation satellites, measurement model for ISLs and ground observations, and the batch least-square filter for estimating OD parameters. As numerical simulations are performed to analyze the OD performances, the present study focuses on investigating the effects of ISL measurements on the OD accuracy of KRNSS. Simulation results show that the use of ISLs can considerably enhance the OD accuracy to one meter (design preference) under certain distributions of ground stations.

Modeling and Characterization of the Abnormal Hump in n-Channel Amorphous-InGaZnO Thin-Film Transistors After High Positive Bias Stress

Jungmin Lee,Sungju Choi,Seong Kwang Kim,Sung-Jin Choi,Dae Hwan Kim,Jisun Park,Dong Myong Kim IEEE 2015 IEEE electron device letters Vol.36 No.10

<P>Hump characteristics of n-channel amorphous indium-gallium-zinc-oxide (a-InGaZnO) thin-film transistors (TFTs) after positive gate and drain bias stress (PGDBS) are investigated. With the increase of the PGDBS time, we observed not only a shift of the threshold voltage (V<SUB>T</SUB>) but also a generation of the hump in the transfer characteristics. The hump is caused by the localized trapping of electrons in the gate insulator over the gate-source overlap region by the high vertical field during the PGDBS (V<SUB>GS</SUB> = 30, V<SUB>DS</SUB> = 30; V<SUB>GD</SUB> = V<SUB>GS</SUB> - V<SUB>DS</SUB> = 0 V). The TFT with a hump after PGDBS is modeled as a series connection of main and parasitic TFTs. The parasitic TFT for the electron trapping at the gate-source overlap region has a higher threshold voltage (V<SUB>Tp</SUB>) and a shorter effective channel length (L<SUB>chp</SUB> ≅ Lov) compared with those (V<SUB>Tm</SUB> and L<SUB>ch</SUB>) of the main TFT.</P>

Effect of charge trap layer thickness on the charge spreading behavior within a few seconds in 3D charge trap flash memory

Choi, Bongsik,Lee, Jiyong,Yoon, Jinsu,Jeon, Minsu,Lee, Yongwoo,Han, Jungmin,Lee, Jieun,Park, Jinhee,Kim, Yeamin,Kim, Dong Myong,Kim, Dae Hwan,Chung, Sungyong,Lim, Chan,Choi, Sung-Jin Institute of Physics 2018 Semiconductor science and technology Vol.33 No.10

<P>Charge spreading behavior within a few seconds, referred to as early retention, was comprehensively investigated in 24 word-line stacked tube-type 3D NAND flash memory. We thoroughly explored the charge spreading behavior from the perspectives of both electron and hole spreading in 3D NAND flash memory with different charge trap layer thicknesses at various programming and erasing levels for solid and checkerboard patterns to provide guidelines for minimizing and optimizing the charge spreading.</P>

Potential Contamination Sources on Fresh Produce Associated with Food Safety

Choi, Jungmin,Lee, Sang In,Rackerby, Bryna,Moppert, Ian,McGorrin, Robert,Ha, Sang-Do,Park, Si Hong The Korean Society of Food Hygiene and Safety 2019 한국식품위생안전성학회지 Vol.34 No.1

신선한 농산물 섭취와 관련된 많은 장점들이 전세계적으로 발표되고 있으며, 지속적인 섭취를 장려하고 있다. 일반적으로 과일과 채소는 최소한으로 가공되기 때문에 천연의 성분들이 건강을 증진시키는 역할을 하기도 하지만 그만큼 질병을 일으킬 수 있는 매개체가 존재할 수 있는 가능성이 매우 높다. 세계 보건기구 (WHO)의 보고서에 따르면 10명 중 1명이 식품에 의해 발생하는 질병으로 고통 받고 있으며, 전 세계적으로 매년 42만 명이 식중독으로 사망하는 것으로 밝혀졌다. 이러한 신선 식품은 농장에서 수확할 때부터 소비자의 식탁에 오르기까지 다양한 경로에서 쉽게 오염 될 수 있다. 본 리뷰논문에서는 신선식품에 의해 발생할 수 있는 질병을 이해하기 위해 화학적, 생물학적, 그리고 물리학적 위험요소로부터 식중독을 일으키는 원인과, 증상, 그리고 검출 방법에 대해서 기술 하였다. 화학적 위험요소의 대표적인 예로는 농약(살충제, 살균제, 및 제초제), 천연 독소 (곰팡이 독소 및 식물 독소), 그리고 중금속 (수은 및 카드뮴) 등이 있으며 이는 크로마토그래피 및 나노 기술 등을 이용하여 검출 할 수 있다. 하지만, 여러 실험에도 불구하고 화학적 위험 요소는 그 구조가 다양하기 때문에 위험 요소를 검출하는 하나의 표준 방법을 수립하기 힘들다. 신선한 과일과 채소는 영양분과 수분이 풍부하기 때문에 박테리아성 병원균 (Salmonella, E. coli O157: H7, Shigella, Listeria monocytogenes, Bacillus cereus), 바이러스 또는 기생충에 의해 쉽게 오염이 되며, 이를 검출하기 위해 주로 다양한 분자 생물학적 기술이 사용되고 있다. 마지막으로 물리적 위험요소인 유리, 금속, 자갈 등과 같은 매개체는 가공 공정 중에 식품에 유입되어 소비자에게 신체적 상해를 줄 수 있다. 이러한 위험요소를 줄이기 위해서 X-선 검사와 같은 투시 시스템을 이용하여 위해물질을 탐지하거나, 생산에 관여하는 직원 교육을 통해 2차 감염을 줄일수 가 있다. The health benefits associated with consumption of fresh produce have been clearly demonstrated and encouraged by international nutrition and health authorities. However, since fresh produce is usually minimally processed, increased consumption of fresh fruits and vegetables has also led to a simultaneous escalation of foodborne illness cases. According to the report by the World Health Organization (WHO), 1 in 10 people suffer from foodborne diseases and 420,000 die every year globally. In comparison to other processed foods, fresh produce can be easily contaminated by various routes at different points in the supply chain from farm to fork. This review is focused on the identification and characterization of possible sources of foodborne illnesses from chemical, biological, and physical hazards and the applicable methodologies to detect potential contaminants. Agro-chemicals (pesticides, fungicides and herbicides), natural toxins (mycotoxins and plant toxins), and heavy metals (mercury and cadmium) are the main sources of chemical hazards, which can be detected by several methods including chromatography and nano-techniques based on nanostructured materials such as noble metal nanoparticles (NMPs), quantum dots (QDs) and magnetic nanoparticles or nanotube. However, the diversity of chemical structures complicates the establishment of one standard method to differentiate the variety of chemical compounds. In addition, fresh fruits and vegetables contain high nutrient contents and moisture, which promote the growth of unwanted microorganisms including bacterial pathogens (Salmonella, E. coli O157: H7, Shigella, Listeria monocytogenes, and Bacillus cereus) and non-bacterial pathogens (norovirus and parasites). In order to detect specific pathogens in fresh produce, methods based on molecular biology such as PCR and immunology are commonly used. Finally, physical hazards including contamination by glass, metal, and gravel in food can cause serious injuries to customers. In order to decrease physical hazards, vision systems such as X-ray inspection have been adopted to detect physical contaminants in food, while exceptional handling skills by food production employees are required to prevent additional contamination.

Effect of PECVD Gate SiO2 Thickness on the Poly-Si/SiO2 Interface in Low-Temperature Polycrystalline Silicon TFTs

Choi Byoungdeog,Choi Pyungho,Kim Soonkon,Jeon Bohyeon,Lee Jongyoon,Jungmin Park 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.2

This study investigates the eff ect of the gate SiO 2 thickness (80, 100, and 130 nm) deposited by plasma enhanced chemical vapor deposition on the interface and reliability characteristics of low-temperature polycrystalline silicon thin fi lm transistors. Field eff ect mobility is signifi cantly degraded as the gate oxide thickness decreases. The border trap density (N bt ) extracted from capacitance–voltage hysteresis exhibits no trend with respect to the gate oxide thickness, indicating that fi eld eff ect mobility is not governed by N bt . The quantitative interface trap density (N it ) was obtained using a 3-terminal charge pumping method; results showed that N it decreased as the gate oxide thickness increased. However, it was observed that the threshold voltage (V th ) shift during negative bias temperature stress is worse in the thicker SiO 2 fi lm, which has a low N it . After activation annealing, the amount of hydrogen in the gate oxide increased as the thickness of the insulator was raised. This in turn caused a larger shift in V th . To validate this mechanism, the amount of hydrogen with respect to the device depth was analyzed via secondary ion mass spectroscopy. It has been found that the presence of more hydrogen concentration in the SiO 2 fi lm and the interface to the thicker SiO 2 results in more V th shifts under bias temperature stress.

Effect of ALD- and PEALD- Grown Al2O3 Gate Insulators on Electrical and Stability Properties for a-IGZO Thin-Film Transistor

Jungmin Park,Hyojung Kim,Pyungho Choi,Bohyeon Jeon,Jongyoon Lee,Changyong Oh,Bosung Kim,Byoungdeog Choi 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.4

This study investigated the electrical and stability characteristics of Al 2 O 3 as a gate insulator, which was deposited by variousatomic layer deposition methods in top-gate staggered amorphous InGaZnO (a-IGZO) thin fi lm transistors. A trimethylaluminumprecursor was used as an Al source, and H 2 O gas (H 2 O device) and O 2 plasma with a long plasma time (O 2 LP device)and a short plasma time (O 2 SP device) were used as oxidants. The initial electrical characteristics, including the hysteresis,on–off current ratio, and subthreshold swing, were superior in the H 2 O device compared to the O 2 LP and O 2 SP devices. Inthe positive bias stress (PBS) results, the degradation characteristics showed a tendency similar to the transfer properties. However, under the negative bias illumination stress (NBIS), the stability of the H 2 O device was signifi cantly reduced comparedto the O 2 LP and O 2 SP devices. In this paper, the mechanism of instability, which has opposite results in terms of thePBS and NBIS for the three devices, was identifi ed using capacitance–voltage, three-terminal charge pumping as electricalanalysis techniques and secondary ion mass spectroscopy (SIMS) as a physical analysis technique. It was confi rmed thatthe surface oxidation of a-IGZO deteriorates the interfacial properties, causing the transfer characteristics to degrade. Thecarbon of the Al 2 O 3 fi lm identifi ed via SIMS analysis acts as a trap layer, causing deterioration in the PBS. Alternatively, inthe NBIS, it was observed that the carbon acts as a capture site for photo-excited holes, thereby promoting device stability.

Potential Contamination Sources on Fresh Produce Associated with Food Safety

Jungmin Choi,Sang In Lee,Bryna Rackerby,Ian Moppert,Robert McGorrin,하상도,박시홍 한국식품위생안전성학회 2019 한국식품위생안전성학회지 Vol.34 No.1

The health benefits associated with consumption of fresh produce have been clearly demonstrated and encouraged by international nutrition and health authorities. However, since fresh produce is usually minimally processed, increased consumption of fresh fruits and vegetables has also led to a simultaneous escalation of foodborne illness cases. According to the report by the World Health Organization (WHO), 1 in 10 people suffer from foodborne diseases and 420,000 die every year globally. In comparison to other processed foods, fresh produce can be easily contaminated by various routes at different points in the supply chain from farm to fork. This review is focused on the identification and characterization of possible sources of foodborne illnesses from chemical, biological, and physical hazards and the applicable methodologies to detect potential contaminants. Agro-chemicals (pesticides, fungicides and herbicides), natural toxins (mycotoxins and plant toxins), and heavy metals (mercury and cadmium) are the main sources of chemical hazards, which can be detected by several methods including chromatography and nano-tech-niques based on nanostructured materials such as noble metal nanoparticles (NMPs), quantum dots (QDs) and mag-netic nanoparticles or nanotube. However, the diversity of chemical structures complicates the establishment of one standard method to differentiate the variety of chemical compounds. In addition, fresh fruits and vegetables contain high nutrient contents and moisture, which promote the growth of unwanted microorganisms including bacterial pathogens (Salmonella, E. coli O157: H7, Shigella, Listeria monocytogenes, and Bacillus cereus) and non-bacterial pathogens (norovirus and parasites). In order to detect specific pathogens in fresh produce, methods based on molec-ular biology such as PCR and immunology are commonly used. Finally, physical hazards including contamination by glass, metal, and gravel in food can cause serious injuries to customers. In order to decrease physical hazards, vision systems such as X-ray inspection have been adopted to detect physical contaminants in food, while exceptional han-dling skills by food production employees are required to prevent additional contamination.

Orbit Determination of Korea Regional Navigation Satellite System Using Inter-Satellite Links and Ground Observations

Choi, Jungmin,Oh, Hyungjik,Park, Chandeok,Park, Sang-Young The Korean Society for Aeronautical and Space Scie 2017 International Journal of Aeronautical and Space Sc Vol.18 No.2

This study presents the orbit determination (OD) of a candidate Korea Regional Navigation Satellite System (KRNSS) using both inter-satellite links (ISLs) and ground observations. The candidate constellation of KRNSS is first introduced. The OD algorithm based on both ISL and ground observation is developed, and consists of three main components: dynamic model for Korean navigation satellites, measurement model for ISLs and ground observations, and the batch least-square filter for estimating OD parameters. As numerical simulations are performed to analyze the OD performances, the present study focuses on investigating the effects of ISL measurements on the OD accuracy of KRNSS. Simulation results show that the use of ISLs can considerably enhance the OD accuracy to one meter (design preference) under certain distributions of ground stations.

A Study on Relationship between Physical Elements and Tennis/Golf Elbow

Jungmin Choi,Jungwoo Park,Hyunseung Kim 대한인간공학회 2017 大韓人間工學會誌 Vol.36 No.3

Objective: The purpose of this research was to assess the agreement between job physical risk factor analysis by ergonomists using ergonomic methods and physical examinations made by occupational physicians on the presence of musculoskeletal disorders of the upper extremities. Background: Ergonomics is the systematic application of principles concerned with the design of devices and working conditions for enhancing human capabilities and optimizing working and living conditions. Proper ergonomic design is necessary to prevent injuries and physical and emotional stress. The major types of ergonomic injuries and incidents are cumulative trauma disorders (CTDs), acute strains, sprains, and system failures. Minimization of use of excessive force and awkward postures can help to prevent such injuries Method: Initial data were collected as part of a larger study by the University of Utah Ergonomics and Safety program field data collection teams and medical data collection teams from the Rocky Mountain Center for Occupational and Environmental Health (RMCOEH). Subjects included 173 male and female workers, 83 at Beehive Clothing (a clothing plant), 74 at Autoliv (a plant making air bags for vehicles), and 16 at Deseret Meat (a meat-processing plant). Posture and effort levels were analyzed using a software program developed at the University of Utah (Utah Ergonomic Analysis Tool). The Ergonomic Epicondylitis Model (EEM) was developed to assess the risk of epicondylitis from observable job physical factors. The model considers five job risk factors: (1) intensity of exertion, (2) forearm rotation, (3) wrist posture, (4) elbow compression, and (5) speed of work. Qualitative ratings of these physical factors were determined during video analysis. Personal variables were also investigated to study their relationship with epicondylitis. Logistic regression models were used to determine the association between risk factors and symptoms of epicondyle pain. Results: Results of this study indicate that gender, smoking status, and BMI do have an effect on the risk of epicondylitis but there is not a statistically significant relationship between EEM and epicondylitis. Conclusion: This research studied the relationship between an Ergonomic Epicondylitis Model (EEM) and the occurrence of epicondylitis. The model was not predictive for epicondylitis. However, it is clear that epicondylitis was associated with some individual risk factors such as smoking status, gender, and BMI. Based on the results, future research may discover risk factors that seem to increase the risk of epicondylitis. Application: Although this research used a combination of questionnaire, ergonomic job analysis, and medical job analysis to specifically verify risk factors related to epicondylitis, there are limitations. This research did not have a very large sample size because only 173 subjects were available for this study. Also, it was conducted in only 3 facilities, a plant making air bags for vehicles, a meat-processing plant, and a clothing plant in Utah. If working conditions in other kinds of facilities are considered, results may improve. Therefore, future research should perform analysis with additional subjects in different kinds of facilities. Repetition and duration of a task were not considered as risk factors in this research. These two factors could be associated with epicondylitis so it could be important to include these factors in future research. Psychosocial data and workplace conditions (e.g., low temperature) were also noted during data collection, and could be used to further study the prevalence of epicondylitis. Univariate analysis methods could be used for each variable of EEM. This research was performed using multivariate analysis. Therefore, it was difficult to recognize the different effect of each variable. asically, the difference between univariate and multivariate analysis is that univariate analysis deals wit

이름 기반 네트워크에서의 캐시 교체 정책 성능 비교

유정민(Jungmin Yoo),최훈규(Hoongyu Choi),권태경(Ted "Taekyong" Kwon),최양희(Yanghee Choi) 한국통신학회 2013 한국통신학회 학술대회논문집 Vol.2013 No.11