Triboelectric Nanogenerator (TENG)를 위한 Rutile TiO₂ 박막 성능 및 특성 평가

문지현(Ji-Hyeon Moon),김한재(Han-Jae Kim),김효배(Hyo-Bae Kim),안지훈(Ji-Hoon Ahn) 한국표면공학회 2021 한국표면공학회지 Vol.54 No.6

As energy harvesting technology becomes important in relation to environmental issues, piezoelectric materials that convert mechanical energy into electrical energy are attracting attention. However, PZT, a representative material for piezoelectricity, is becoming difficult to use due to the problem that its components can cause environmental pollution. For this reason, recent research suggests a triboelectric nanogenerator (TENG) that generates energy through the combined effect of triboelectricity and electric induction for alternative piezoelectric devices. In TENG, electrical power is determined by the dielectric constant, thickness, and grain generation of the charged material. Therefore, in this study, a Rutile phase TiO₂ thin film with high dielectric constant was formed using the spin-coating process and the effect of annealing was investigated. For electrical analysis, a TENG device was fabricated using PTFE as a material with an opposite charge, and electrical output according to film thickness and grain formation was comparatively analyzed.

고온 환경에서 KSLV-I 발사체용 GPS 안테나의 성능 분석

문지현(Ji-Hyeon Moon),권병문(Byung-Moon Kwon),최형돈(Hyung-Don Choi),정호락(Ho-Rac Jung) 한국항공우주연구원 2007 항공우주기술 Vol.6 No.1

GPS 안테나는 위성발사체의 전 비행 구간에서 GPS 위성 신호를 정상적으로 수신하기 위하여 발사체의 외피에 설치되어야 한다. 위성발사체의 표면 온도는 발사체가 대기권을 통과하면서 발생하는 열공력의 영향으로 급격하게 상승하며 발사체 외피에 설치되는 GPS 안테나는 극심한 고온 환경에 직접적으로 노출된다. 따라서 위성발사체의 외피에 설치되는 GPS 안테나에 대한 고온 환경 시험 규격은 발사체 내부 시스템의 고온 환경 시험 규격보다 더 가혹하게 설정되어야 한다. 본 논문에서는 KSLV-I 발사체에 탑재될 GPS 안테나의 고온 환경에서 성능 분석 절차 및 결과를 기술하며, GPS 안테나가 고온 환경에서 물리적인 변형이나 내부 LNA(Low Noise Amplifier)의 성능 저하 없이 정상적으로 동작하였음을 보여주고 있다. For a GPS antenna to normally receive GPS satellite signals during full flight mission of a satellite launch vehicle, it should be installed on skin of the vehicle. The surface of a launch vehicle is drastically heated up due to aerodynamic heating effect during flight, so that the GPS antenna mounted on surface of the launch vehicle is directly exposed to extremely hot temperature environment. Hot temperature test specification of the GPS antenna, therefore, is severer than inner components. This paper describes that procedures and results of performance analysis of the GPS antenna for KSLV-I under hot temperature environment. The GPS antenna was not deformed physically and inner LNA(Low Noise Amplifier) operated normally without performance degradation.

진공환경에서 GPS 수신기의 성능분석

문지현(Ji-Hyeon Moon),권병문(Byung-Moon Kwon),신용설(Yong-Sul Shin),최형돈(Hyung-Don Choi) 한국항공우주연구원 2009 항공우주기술 Vol.8 No.1

본 논문에서는 KSLV-I 전자탑재물의 하나인 GPS 수신기의 진공환경에서의 동작성을 검증하기 위하여 수행된 단품수준의 열진공시험 및 시스템수준의 진공시험에 대하여 소개하고 GPS 수신기의 운용방법 및 진공환경에서의 성능분석 결과를 제시하며, 압력변화 및 고진공 조건에서 나타날 수 있는 전자부품의 손상 및 성능저하 정도를 GPS 수신기에서 계산된 최대신호대잡음비와 항법해 오차를 분석한 추적성능 및 항법성능을 통해 살펴보았다. In order to verify the operability of a GPS receiver which is one of the KSLV-I onboard electrical equipments under the vacuum conditions, this paper describes the operation methods and performance results of the GPS receiver under the thermal-vacuum and vacuum environments. The damages and degradations of electrical parts of the GPS receiver caused by the pressure change and high-degree vacuum conditions are analyzed in terms of tracking and navigation capabilities through the signal-to-noise ratio and navigation error.

KSLV-Ⅰ 상단조립체의 전자파시험에서 GPS 수신기 시스템의 성능분석

문지현(Ji-Hyeon Moon),권병문(Byung-Moon Kwon),신용설(Yong-Sul Shin),최형돈(Hyung-Don Choi) 한국항공우주연구원 2008 항공우주기술 Vol.7 No.1

본 논문에서는 KSLV-Ⅰ 상단조립체에 대하여 수행된 시스템 인증수준의 전자파시험에서 GPS 수신기 시스템을 위한 시험 구성 및 운용 방법을 소개하고 성능분석 결과를 기술한다. GPS 수신기 시스템은 이미 단품 수준에서 수차례의 설계 변경을 통하여 MIL-STD￢461E 기준으로 규정된 KSLV-Ⅰ 상단 전자장비 시험 규격을 만족함을 확인하였다. 시스템 인증수준으로 수행된 전자파시험에서 GPS 수신기 시스템은 다른 탑재물들과의 전자파적 간섭에도 정상적으로 동작하였으며 전계필드 입사 및 정전기 방전의 조건에서도 성능저하가 발생하지 않아. KSLV-Ⅰ 상단 전자파환경 조건에서의 동작성이 검증되었다. This paper introduces test configuration and operation method for the GPS receiver system under electromagnetic test of KSLV-Ⅰ upper-stage as a system qualification level and describes performance analysis of the test results. The GPS receiver system has clearly passed the electromagnetic test specifications of component level which is based on MIL-STD-461E through several design changes. Under electromagnetic test as a system qualification level, the GPS receiver system normally operates in spite of electromagnetic interferences with other systems. Performance of the GPS receiver system is also, not degraded on the condition of electromagnetic field incidence and electrostatic discharge. The KSLV-Ⅰ GPS receiver system, as a result, is verified on the electromagnetic condition of the KSLV-Ⅰ upper-stage.

GPS 수신기 데이터의 후처리를 통한 항공기 비행시험 기준궤적 생성

문지현(Ji-Hyeon Moon),권병문(Byung-Moon Kwon),신용설(Yong-Sul Shin),최형돈(Hyung-Don Choi) 한국항공우주연구원 2010 항공우주기술 Vol.9 No.1

본 논문에서는 항공기 비행시험의 기준 비행 궤적을 획득하기 위해 수행된 CPS 수신기 데이터의 후처리에 대하여 다룬다. 항공기 비행시험은 나로우주센터의 추적 및 통신 장비의 성능을 검증하기 위해 나로호 탑재 시스템과 지상 장비들에 대해 수행된 통합 시험으로서 2007년부터 수차례 수행되었다. 항공기 시험에서 추적 및 항법 장비의 성능을 분석하기 위해서는 데이터 비교를 위한 참값인 기준 데이터가 반드시 필요하므로 본 논문에서는 이를 위해 성능이 검증된 이중주파수용 CPS 수신기인 NovAtel 사의 DL-V3 수신기를 운용하여 비행 데이터를 수집하고, 검증된 후처리 프로그램인 GrafNav로 후처리하여 수십 ㎝ 오차 수준을 가지는 기준 궤적을 생성하였다. This paper deals with a post-processing of GPS receiver data in order to acquire a reference flight trajectory of an aircraft test. The flight test using an aircraft that is carried out several times since 2007 is the integrated test to verify the performance of the tracking and communications facilities in Naro Space Center and Jeju Tracking Center. In order to analyze performance of the tracking and navigation equipments, true reference data should be used for performance comparisons. Therefore off-the-shelf commercial GPS receiver, DL-V3 made by NovAtel Inc., is operated on the test to collect the GPS navigation data and the collected data is post-processed by GrafNav which is the off-the-shelf post-processing program made by NovAtel Inc. Through the post-processing of the collected data, a reference trajectory is generated with small error range about several decade centimeter level.

발사체 시나리오에서 PLL 루프필터의 대역폭에 따른 GPS 수신기의 성능 분석

문지현(Ji-Hyeon Moon),권병문(Bung-Moon Kwon),신용설(Yong-Sul Shin),최형돈(Hyung-Don Choi) 한국항공우주연구원 2013 항공우주기술 Vol.12 No.1

본 논문에서는 GPS 수신기의 반송파 추적루프를 3차 PLL로 구성하고 대역폭을 변화시켰을 때 발사체 시나리오를 이용한 시뮬레이션에서 GPS 수신기의 추적 및 항법성능을 분석한다. 시험에 사용된 GPS 수신기는 발사체가 가지는 동특성으로 인해 3차 PLL로 구성된 추적루프의 대역폭에 따라 추적 및 항법성능에 차이가 나타났으며, 특히 대역폭이 좁게 설정된 경우에는 신호추적을 놓쳐 항법 계산을 하지 못하는 경우도 발생하였다. This paper describes the analysis of the tracking and navigation performance of a GPS receiver in a launch vehicle simulation when the carrier tracking loop is designed as a 3rd order phase-locked loop with variable bandwidths. There are differences of tracking and navigation performance according to the variable bandwidths under the dynamics condition. When the bandwidth is set to narrow, the GPS receiver could not track the satellite signals so that the navigation information could not be calculated.

CIGS 태양전지용 Cd-Free 버퍼층 제조

문지현 ( Jee Hyun Moon ),김지현 ( Ji Hyeon Kim ),유인상 ( In Sang Yoo ),박상준 ( Sang Joon Park ) 한국공업화학회 2014 공업화학 Vol.25 No.6

Indium hydroxy sulfide (In(OH)xSy) as a cadmium (Cd)-free buffer layer for CuInGaSe2 (CIGS) solar cells was prepared by the chemical bath deposition (CBD) and the reaction time was optimized. The band gap energy and transmittance data alongside the thickness results from the direct observation with focused ion beam system (FIB) could be a powerful tool for optimizing the conditions. In addition, X-ray diffractometer (XRD), X-ray photoelectron microscopy (XPS), and scanning electron microscope (SEM) were also employed for the layer characterization. The results indicated that the optimum reaction time for In(OH)xSy buffer layer deposition by CBD was 20 min at 70 ℃ under the conditions employed. At the optimum conditions, the buffer layer thickness was near 57 nm and the band gap energy was 2.7 eV. In addition, it was found that there was no XPS peak shift in between the buffer layers deposited on molybdenum (Mo)/glass and that on CIGS layer.

Relationship Between Prostate Volume and Lower Urinary Tract Symptom in Health Checkup Subjects

Hyeon Ju Kim(김현주),Ji Hyun Moon(문지현),Yun Hwan Oh(오윤환),Mi Hee Kong(공미희),Kyung Kgi Park(박경기),Jung Sik Huh(허정식) 대한비뇨기종양학회 2020 대한비뇨기종양학회지 Vol.18 No.1

Purpose: This study aimed to evaluate the relationship between prostate volume and lower urinary symptom (LUTS) in subjects undergoing health checkup and to know the usefulness of TRUS in health screening. Materials and Methods: The study was conducted in 883 men aged ≥20 years who underwent TRUS for health screening. All participants had filled in the international prostate symptom score (IPSS) and were tested for prostate-specific antigen; prostate volume, central gland volume, and transitional zone index were measured using TRUS. We analyzed the differences in the IPSS by prostate volume and differences in prostate volume by severity of LUTS and correlation between prostate volume and each component of IPSS. Results: There were differences in the total IPSS, storage score, and voiding score between the subjects with prostate volumes of ≥30 mL or not (p=0.027, p=0.037, and p=0.029, respectively). However, the differences were found only for urgency and weak stream. The volume of the severe symptom group was bigger than those of the mild and moderate symptom groups (p=0.002 and p=0.014). The correlation between prostate volume and IPSS was significant only for the between the central volume and nocturia (r=0.112, p<0.01). Conclusions: The relationship between prostate volume and urinary symptoms showed significant but low correlation and found only in some components. For the accurate diagnosis, it would be more useful to accompany various voiding-related surveys in addition to TRUS during health screening.

나로우주센터 발사장에서 나로호 GPS 수신기 시스템의 운용

권병문(Byung-Moon Kwon),문지현(Ji-Hyeon Moon),신용설(Yong-Sul Shin),최형돈(Hyung-Don Choi),조광래(Gwang-Rae Cho) 한국항공우주학회 2010 韓國航空宇宙學會誌 Vol.38 No.7

본 논문은 고흥에 위치한 나로우주센터 발사장에 나로호가 발사대기하고 있을 때에 나로호에 탑재된 GPS 수신기 시스템의 운용결과에 대하여 다룬다. 나로호가 발사대에서 수직으로 기립하고 있는 동안에 GPS 수신기 시스템을 포함한 나로호의 모든 탑재장비들은 나로호의 이륙 직전까지 동작상태와 성능이 점검되어야 한다. 나로호에 탑재된 GPS 수신기는 기체 표면에 설치된 3개의 패치형 GPS 안테나와 연결된다. 각각의 GPS 안테나에서 수신된 GPS 위성신호를 바탕으로 나로호가 발사대에 발사대기중일 때에 발사장 환경에 의해 GPS 수신기에서 관찰된 신호간섭과 다중경로로 인해 발생한 현상 등을 분석한다. This paper describes the operation results of the GPS receiver system for KSLV (Korea Space Launch Vehicle)-I on the launch site at Naro Space Center that is the first spaceport of South Korea located at Goheung. All equipments of KSLV-I including the GPS receiver system should be monitored and controlled through hard-wired interface during KSLV-I is on standby at the launch pad. The GPS receiver for KSLV-I is connected to triple almost omni-directional patch antennas mounted on the cylindrical surface of KSLV-I that should be erected vertically on the launch pad until lift-off. Signal interference and multipath effects observed in the GPS receiver on the launch site are analyzed in this paper based on the GPS signals received from each GPS antenna.

위성발사체용 GPS 수신기 시스템의 전자파시험

권병문(Byung-Moon Kwon),문지현(Ji-Hyeon Moon),최형돈(Hyung-Don Choi),조광래(Gwang-Rae Cho) 한국항공우주학회 2007 韓國航空宇宙學會誌 Vol.35 No.4

본 논문은 전자파 방사 및 내성 요구조건을 만족하도록 개발되어야 하는 위성발사체용 GPS 수신기 시스템에 대하여 수행된 전자파시험을 다루고 있다. 수차례에 걸쳐서 수행된 전자파시험을 통하여 전자파환경에서의 성능이 개선된 GPS 수신기 시스템은 주어진 전자파환경 규격을 모두 만족하였다. 본 논문은 수행된 전자파시험의 Part Ⅰ으로 시험개요와 MIL-STD-461E에 주어진 CE102, CE106, RE102 규격에 대한 방사시험 결과를 제시한다. This paper deals with electromagnetic tests of the GPS receiver system that should be developed to satisfy emission and susceptibility requirements for a satellite launch vehicle. Performance of the GPS receiver system against electromagnetic environment that is improved through several tests satisfies all requirements about electromagnetic tests. The outline of the electromagnetic tests and emission test results of CE102, CE106 and RE102 on MIL-STD-461E are described in Part Ⅰ.