초소형위성 SNIPE(Scale Magnetospheric and Ionospheric Plasma Experiment) 시제인증모델의 발사환경시험 및 분석

김민기,김해동,최원섭,김진형,김기덕,김지석,조동현,Kim, Min-Ki,Kim, Hae-Dong,Choi, Won-Sub,Kim, Jin-Hyung,Kim, KiDuck,Kim, Ji-Seok,Cho, Dong-Hyun 한국우주과학회 2021 우주기술과 응용 Vol.1 No.3

본문은 과학관측임무 초소형위성인 SNIPE(Scale magNetospheric and Ionospheric Plasma Experiment)의 시제인증모델(EQM)에 대한 발사환경시험 수행 결과 및 이를 통해 얻을 수 있는 신뢰성 있는 초소형위성 개발 방향에 대해 논한다. SNIPE는 우주기상관측을 포함한 다양한 탑재체를 지닌 6U급 초소형위성으로 4기가 편대비행을 하며 임무를 수행한다. 다수의 비행모델 제작 전 시제인증모델을 통해 먼저 설계 및 제작의 유용성을 검증하고자 하였다. 시제인증모델의 발사환경시험은 2019년 1차 시험이 수행되었고, 여기서 발견된 일부 문제점을 교정하여 2021년에 2차 시험을 수행함으로써 모든 문제가 해결되었음을 확인할 수 있었다. 두 차례의 시험에서 특이할 점은 1차 시험의 발사관과 2차 시험의 발사관이 다르다는 점인데, 1차 시험용 발사관과 달리 2차 시험의 발사관은 내부의 초소형위성을 고정하는 기능이 있어서 내부 초소형위성이 실제 받는 구조적 하중이 1차 시험에 비해 훨씬 경감되었다는 점이다. 본 논문은 두 시험의 결과로 나타난 특징을 분석하고, 차후 여타 초소형위성의 구조 설계에 반영할 수 있는 지침들을 제시하였다. This paper discusses the results of launch environment tests for the engineering qualification model (EQM) of nanosatellite Scale magNetospheric and Ionospheric Plasma Experiment (SNIPE) for scientific missions and lessons learned for the design of nanosatellites. SNIPE is a group of four formation-flying 6U nanosatellites with a range of payloads for missions including space weather measurement. We developed the EQM to verify the preliminary design prior to fabricating the flight model. Launch environment test of EQM was conducted for the first time in 2019, and all failures were corrected and verified at the second test conducted in 2021. A notable point of the two tests is that the nanosatellite deployer used in the first test is different from that of the second test. The second deployer has the capability to fix the internal satellite whereas the first deployer just contains and deploys the satellite. Thus actual mechanical loads the satellite receives is reduced for the second test compared to the first test. This work compares the mechanical responses of two tests and proposes general guidelines for structural design of nanosatellites.

국내에서 보고된 비회귀성 반회후두신경 증례 분석

김민기,최영수,김기현,배자성,이동호,성기영,김정수,박우찬,Min-Ki Kim,M,D,Young-Soo Choi,M,D,Ki-Hyun Kim,M,D,Ja-Sung Bae,M,D,Dong-Ho Lee,M,D,Ki Young Sung,M,D,Jung-Soo Kim,M,D,and Woo-Chan Park,M,D 대한갑상선-내분비외과학회 2009 The Koreran journal of Endocrine Surgery Vol.9 No.1

Purpose: This study was performed to readjust the clinical implications of a nonrecurrent laryngeal nerve by assessing the reported Korean cases of a nonrecurrent laryngeal nerve. Methods: We analyzed the cases of nonrecurrent laryngeal nerve that have been reported in Korea between 1997 and 2008 by reviewing the literature. An internet search was conducted in the NDSL (National Digital Science Library) and the Korean Medical Database. Results: The data included 3 men and 25 women with an average age of 45.1 (age range: 28∼58). All the cases were right-sided, and the incidence rate was 0.38% and 0.86% in two articles, respectively. There was a type I variation in 4 cases (17.4%), type IIa in 19 cases (82.6%), and the others are unknown. Twenty-five cases (89.3%) had the vascular anomaly called arteria lusoria. Only 8 cases (28.6%) were preoperatively predicted as possibly having a nonrecurrent laryngeal nerve. Iatrogenic nerve injury developed in 1 case (3.57%) with a type I variation during the postoperative period. Conclusion: A similar tendency for the incidence rate, the genderratio, the type distribution and vascular anomaly was observed when comparing the Korean reports with those reports of overseas. The nonrecurrent laryngeal nerve can be preoperatively predicted if proper attention is given when vascular anomaly is noted on CT or USG, and injury will be avoided by intraoperatively following the standard operation technique. There is currently an increasing incidence of thyroid diseases, and so adequate attention must be given to the possibility of a nonrecurrent laryngeal nerve and its management. (Korean J Endocrine Surg 2009;9:24-29)

Advanced Dual Refrigerant Expansion Cycle for LNG Liquefaction

김민기,김문규,이기환,김효빈,이동훈,민준호,김진모,Kim, Minki,Kim, Mungyu,Lee, Kihwan,Kim, Hyobin,Lee, Donghun,Min, Joonho,Kim, Jinmo Korea Institute of Plane Engineering and Construct 2019 플랜트 저널 Vol.15 No.2

기존 메탄 & 질소 팽창 사이클의 효율 개선을 위해 2개의 메탄 팽창 공정 (cold composite curve에 변곡점을 하나 더 추가하기 위해 warm & cold 2개 공정으로 나눔)과 1개의 질소 팽창 공정을 사용한 천연가스 액화 사이클을 소개하기 위한 논문이다. 이전 질소 팽창 사이클 및 메탄 & 질소 사이클과 비교했을 때, 13.92 및 13.13에서 12.08 kW/ton/day로 효율이 8~15% 정도 개선되었다. 순 현재가치(NPV) 기준으로 한 수명 주기 비용 분석(LCC analysis) 또한 약간의 CAPEX 증가는 있지만 프로젝트 순 현재가치가 개선된 결과를 보여준다. This paper presents a LNG Liquefaction cycle configuration using two stages of methane expansion (i.e. spliting into two stages as warm & cold to generate an additional inflection point within a cold composite curve) and a single stage of nitrogen expansion to improve the efficiency of the conventional Methane & Nitrogen Expansion Cycle. In comparison with Double Nitrogen Expansion Cycel and Methane & Nitrogen Expansion Cycle, the cycle efficiency has increased approximately from 13.92 and 13.13 to 12.08 kW/ton/day (8~15% efficiency increase). A Life Cycle Cost (LCC) analysis based on Net Present Value (NPV) also show an improvement in therms of project NPV, against a minor increment of a CAPEX.

Bee Venom과 Sweet Bee Venom이 지방세포 대사에 미치는 영향

김민기,이시형,신조영,김강산,조남근,임태진,권기록,Kim, Min-Ki,Lee, Si-Hyeong,Shin, Jo-Young,Kim, Kang-San,Cho, Nam-Guen,Rhim, Tae-Jin,Kwon, Ki-Rok 대한약침학회 2007 Journal of pharmacopuncture Vol.10 No.3

Objectives The purpose of this study was to investigate the effects of Bee Venom and Sweet Bee Venom to the primary cultured preadipocyte, adipocytes, and localized fat tissue. Methods Decreased preadipocyte proliferation and decreased lipogenesis are mechanisms to reduce obesity. So, preadipocytes and adipocytes were performed on cell cultures using Sprague-Dawley Rats and treated with 0.01-1mg/ml Bee Venom and Sweet Bee Venom. And porcine skin including fat tissue after treated Bee Venom and Sweet Bee Venom according to the dosage dependent variation are investigated the histologic changes after injection of these Pharmacopuncture. Result Following results were obtained from the preadipocyte proliferation and lipolysis of adipocyte and histologic investigation of fat tissue. 1. Bee Venom and Sweet Bee Venom showed the effect of decreased preadipocyte proliferation depend on concentration. 2. Bee Venom and Sweet Bee Venom showed the effect of decreased the activity of glycerol-3-phosphate dehydrogenase(GPDH) significantly. 3. Bee Venom was not showed the effect of lipolysis, but Sweet Bee Venom was increased in low dosage and decreased in high dosage. 4. Investigated the histologic changes in porcine fat tissue after treated Bee Venom and Sweet Bee Venom, we knew that these Pharmacopuncture was activated nonspecific lysis of cell membranes depend on concentration. Conclusion These results suggest that Bee Venom and Sweet Bee Venom efficiently induces decreased proliferation of preadipocyte and lipolysis in adipose tissue.

센서 모니터링을 위한 칼만필터 기반의 효율적인 적응적 샘플링 기법

김민기,민준기,Kim, Min-Kee,Min, Jun-Ki 한국정보처리학회 2010 정보처리학회논문지D Vol.17 No.3

In sensor network environments, each sensor measures the physical environments according to the sampling period, and transmits a sensor reading to the base station. Thus, the sample period influences against importance resources such as a network bandwidth, and a battery power. In this paper, we propose new adaptive sampling technique that adjusts the sampling period of a sensor with respect to the features of sensor readings. The proposed technique predicts a future readings based on KF (Kalman Filter). By using the differences of actual readings and estimated reading, we identify the importance of sensor readings, and then, we adjust the sampling period according to the importance. In our experiments, we demonstrate the effectiveness of our technique. 센서 네트워크 환경에서는 각 센서는 정의된 샘플링 주기에 따라서 외부 환경을 측정하고 측정된 값을 기지국으로 전송한다. 따라서, 샘플링 주기는 대역폭, 전력량 등 센서들의 중요 자원의 소비에 지대한 영향을 끼친다. 본 논문에서는 측정값 특성에 따라서 센서의 샘플링 주기를 조절하는 새로운 적응적 샘플링 기법을 제안한다. 제안하는 기법은 KF (Kalman-Filter)에 기반하여 미래의 측정값을 예측한다. 그리고, 실측값과 예측값의 차이에 따라서 센서 측정값들의 중요도를 파악하고 이에 따라서 샘플링 주기를 변화시킨다. 실험에서 제안하는 기법의 효과성을 보였다.

설계조건에 따른 고온 초전도 마그넷의 특성변화

김민기,고요,한병성,Kim, Min-Ki,Ko, Yo,Han, Byoung-Sung 한국전기전자재료학회 1995 電氣電子材料學會誌 Vol.8 No.4

Most important study on development of high-Tc superconducting magnet is magnetic properties with design conditions To study optimal design condition of high-Tc superconducting magnet, small size solenoid magnet was designed and simulated. Design conditions are radius of bobbin, radius of magnet, length of magnet, critical cur-rent and notch size. We know that intensity of magnetic fields was controled by critical current and uniformity of magnetic fields was controled by notch size. The optimal design conditions to get the high intensity and uniformity of magnetic field in this experiments were radius of bobbin=3[cm], radius of magnetic=12[cm], length of Z=10[cm], notch size=6[cm] and critical current=12[A].

누설전류를 줄이기 위한 원형 AlGaN/GaN 쇼트키 장벽 다이오드

김민기,임지용,최영환,김영실,석오균,한민구,Kim, Min-Ki,Lim, Ji-Yong,Choi, Young-Hwan,Kim, Young-Shil,Seok, O-Gyun,Han, Min-Koo 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.9

We proposed circular AlGaN/GaN schottky barrier diode, which has no mesa structure near the current path. Proposed device showed low leakage current of 10 nA/mm at -100 V while that of the rectangular device was 34 nA/mm at the same condition. Proposed circular AIGaN/GaN SBD showed high forward current of 88.61 mA at 3,5 V while that of the conventional device was 14.1 mA at the same condition.

IC 패키지 마킹검사를 위한 적응적 다단계 이진화와 정합단위의 동적 선택

김민기,Kim, Min-Ki 한국정보처리학회 2002 정보처리학회논문지B Vol.9 No.2

머신비전을 이용한 IC 패키지 마킹검사 시스템은 입력영상으로부터 검사할 요소들의 위치를 식별하고, 추출된 요소들을 학습된 표준 패턴과 비교하여 마킹의 불량 여부를 판단한다. 본 논문에서는 검사 대상 IC 패키지의 위치 판별, 마킹문자 추출, 핀원딤플 검출과 같은 일련의 작업들에 적합한 적응적 다단계 이진화 방법과 마킹문자의 국소적인 오류검출은 물론 잡영에 강건한 정합단위의 동적 선택 방법을 제안한다. 제안하는 이진화 방법은 이진화 대상 영역과 명도 값의 범위를 제한하여 Otsu의 이진화 알고리즘을 적용함으로써 특정 응용에 적응적인 이진화가 가능하다. 정합단위의 동적 선택 방법은 문자추출 및 배치분석에 대한 결과에 따라 정합단위를 선택한다. 그러므로 문자추출 및 배치분석 과정에서 발생하는 예기치 못한 부적절한 상황에서도 가능한 범위내에서 최소의 정합단위를 선택할 수 있다. 제안된 방법을 구현하여 8종의 IC 패키지, 총 280개의 영상에 대하여 실험한 결과, IC 패키지와 핀원딤플의 검출율은 100%였으며, 마킹상태에 대한 판정은 98.8%의 정확도를 나타내어 제안된 방법이 효과적임을 확인할 수 있었다. IC package marking inspection system using machine vision locates and identifies the target elements from input image, and decides the quality of marking by comparing the extracted target elements with the standard patterns. This paper proposes an adaptive multi-level thresholding (AMLT) method which is suitable for a series of operations such as locating the target IC package, extracting the characters, and detecting the Pinl dimple. It also proposes a dynamic matching unit selection (DMUS) method which is robust to noises as well as effective to catch out the local marking errors. The main idea of the AMLT method is to restrict the inputs of Otsu's thresholding algorithm within a specified area and a partial range of gray values. Doing so, it can adapt to the specific domain. The DMUS method dynamically selects the matching unit according to the result of character extraction and layout analysis. Therefore, in spite of the various erroneous situation occurred in the process of character extraction and layout analysis, it can select minimal matching unit in any environment. In an experiment with 280 IC package images of eight types, the correct extracting rate of IC package and Pinl dimple was 100% and the correct decision rate of marking quality was 98.8%. This result shows that the proposed methods are effective to IC package marking inspection.

딥러닝 기반 차량 통행속도 예측 연구

김민기,류승규 한국ITS학회 2022 한국ITS학회 학술대회 Vol.2022 No.06

나노위성 전개스위치 구현 사례 및 고찰

김민기,Min Ki Kim 한국우주과학회 2023 우주기술과 응용 Vol.3 No.1

Most Nanosatellites are launched in nanosatellite deployers. Nanosatellites in the deployer are turned off during launch, and they start boot sequence after deploying at their mission orbit. For this reason, nanosatellites must have deployment switch. Most of the nanosatellite deployment switch has two part, first is electric switch to boot the satellite system and second is mechanical assembly to push the switch. In most cases, electric switches are installed in the satellite main body, and the switch operations are translated via the mechanical assembly. These implementations are mechanically complicated and hard to guarantee the appropriate operation without the problems due to friction between pusher and satellite structure. This paper proposes the another implementation method of deployment switch for nanosatellites by installing the electric switch outside the main body without any kind of mechanical parts.