Jung-Kyu Lee

Detailed study of the Mare Crisium northern magnetic anomaly

Low-altitude Lunar Prospector Magnetometer (LP-MAG) data for Mare Crisium show two magnetic anomalies near its inner northern and southern edges. Because these features are located inside a basin, they were likely formed by slow cooling of the basins melt, or the partially melted mantle, instead of by any impact-related shock magnetization process. Therefore, they are important for assessing the nature of the ancient dynamo field that produced them. In this study we confine our attention to the simpler northern anomaly (CNA) and use low altitude (∼ 22 km) LP data to model its source body as a dipole and magnetized disks of different radii. We infer that the source is likely located ∼20-30 km from the surface and horizontally localized within a small region (<1∘ or <∼30 km radius). The surface field intensity calculated from the best-fit dipole is in good agreement with that obtained from LP Electron Reflectometer (LP-ER) data. Our magnetization directions are substantially different from two previous studies, largely due to using lower altitude data to perform our inversions. We also find a surprising sensitivity to small changes in source body latitude (∼1∘). The magnetic paleopoles implied by our best-fit models are distant from previous estimates by up to ∼50∘ of great circle arc, and are substantially distant from the Moons present rotation axis. Our results demonstrate how multiple altitude datasets must be used when estimating paleopoles and other properties of even the simplest of the Moons magnetic anomalies.

Development of Flight Software for SIGMA CubeSat

ABSTRACT SIGMA(Scientificcubesat with Instrumentsfor GlobalMagnetic field and rAdiation)CubeSathasbeendevelopedformagneticfieldmeasurementoftheEarthandspaceradiationmeasurementatKyungHeeuniversity.Theflightsoftwareplaysimportantrolesincontrollingthesatelliteandprocessingthedatainthespacemission.Inthispaper,theFlightSoftwarehasbeenimplementedtoprocessallthetasksintheonethreadwithoutRTOS(RealTimeOperatingSystem).ThisisaneffectivemothednotonlytoconcentratethespacemissionofCubeSatbutalsotoreducetheoverheadoftheFlightSoftwarebyconsideringthemissionperformproceduresandthesystemcontrolmethods. 초 록 SIGMA(ScientificcubesatwithInstrumentsforGlobalMagneticfieldandrAdiation)큐브위성은 근 지구 자기장 세기와 우주 방사선량 측정을 위해 경희대학교에서 개발한 초소형 인공위성이다.우주 임무 수행을 위해 비행 소프트웨어는 위성을 제어하고 데이터를 처리하는 중요한 역할을 담당한다.본 연구에서는 SIGMA큐브위성의 임무 수행을 위해 비행 소프트웨어를 구현한 것으로서 일반적으로 임베디드 시스템에서 사용하는 실시간 운영체제를 사용하지 않고 단일 프로세스 내에서 모든 태스크를 처리하도록 구현하였다.이는 SIGMA큐브위성의 임무 수행 절차와 시스템 제어 방법을 고려한 것으로서 소프트웨어의 오버헤드(overhead)를 낮추고 임무 수행에 집중할 수 있는 효과적인 방법이다.KeyWords:CubeSat(큐브위성),FlightSoftware(비행 소프트웨어),SIGMAKHUSAT-3(시그마 KHUSAT-3)

P25.09: First trimester umbilical cord cyst

0.940, P = 0.076) whereas XI VOCALTM (15 slices) showed good correlation with VOCAL TM (12 degrees) (r = 0.961, P = 0.092). ICC between XI VOCAL TM (10 slices) with VOCAL TM (18 degrees) was 0.962 (95% CI 0.920 to 0.982, P = 0.182) whereas between XI VOCAL TM (15 slices) and VOCAL TM (12 degrees) was 0.979 (95% CI 0.957 to 0.990, P = 0.190). The means of the two sets of measurements were not significantly different (mean difference = 1.00 and 0.90; P = 0.136 and 0.285; respectively). 95% limits of agreement were −2.80 to 4.80 between XI VOCALTM (10 slices) and VOCAL TM (18 degrees) and −1.90 to 3.70 between XI VOCALTM (15 slices) and VOCAL TM (12 degrees). There was a small difference in time required to complete the fetal volume measurement between XI VOCAL TM and VOCAL TM when similar number of slices or rotational steps were used (P < 0.05). Conclusion: XI VOCAL TM (with 10, 15, 20 slices) can be used interchangeably with multiplanar technique (1 mm interval) for the measurement of fetal volume. Besides, XI VOCAL TM (10 slices) and XI VOCAL TM (15 slices) can be used interchangeably with VOCAL TM

P36.06: The implication of bilateral hyperechogenic enlargement of kidney for surviving twin after intrauterine death of one monochorionic twin: a case report

Structural or karyotypic discordance in monozygotic twins has important implications for prenatal diagnosis and management, particularly when considering selective fetocide of the affected cotwin. Here we present the ultrasound and cytogenetic findings of monozygotic twins discordant for phenotype and genotype. A 39year-old woman was referred at 15 weeks’ gestation owing to a twin pregnancy with a structurally abnormal co-twin. She had conceived naturally, without any assisted reproductive treatment. Ultrasound revealed a normal male fetus and an abnormal female co-twin with cystic hygroma and hydrops fetalis. We performed a chorionicity scan and presumed a monochorionicity on the basis of sonographic findings, which included a thin dividing membrane, positive ‘T sign’ and single placenta. In addition, a previous ultrasound procedure had shown a single gestational sac at 6 weeks’ gestation. However, the discordant gender was puzzling. Therefore, we decided to perform cytogenetic studies to determine the chorionicity, which is a critical factor in the contemplation of selective fetocide in a twin pregnancy. We conducted genetic amniocentesis for each of the amnionic cavities. Cytogenetic analysis revealed a 46, XY karyotype in the amniocytes of the normal fetus and a 45, X karyotype in the amniocytes of the abnormal co-twin. Molecular analysis of polymorphic small tandem repeat markers by quantitative fluorescent PCR confirmed the presence of monozygotic twins. Considering the high probability of spontaneous death in the abnormal co-twin and the risks associated with selective fetocide, the pregnancy was terminated at 17 weeks’ gestation. Postmortem findings confirmed the prenatal sonographic findings, and the placenta was monochorionic-diamnionic. This case demonstrates that prenatal sonographic determination of the zygosity of twins can be as important as cytogenetic studies in the diagnosis and management of a twin pregnancy with discordant structural anomalies.