• Journal of Positioning, Navigation, and Timing
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• 제11권3호
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• pp.157-161
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• 2022

The Nuri rocket developed by South Korea was launched at approximately 07:00 UT on June 21, 2022. We use GPS observations obtained from the Korean GNSS network to analyze ionospheric total electron content (TEC) disturbances induced by the 2022 Nuri rocket launch. TEC disturbances are observed south over South Korea 4-5 min after the rocket launch. In addition, the maximum depletion in the vertical TEC shows approximately 8 TEC units (TECU). We also compute a horizontal velocity from initial ionospheric disturbances triggered by the 2022 Nuri rocket launch. Its velocity is about 1.4 km/s. It may be related to the rocket's flight trajectory at the observation time of the ionospheric TEC disturbance.

• 천문학회보
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• 제44권2호
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• pp.40.4-40.4
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• 2019

Interplanetary coronal mass ejections (ICMEs) are regarded as one of the most powerful sources of space weather disturbances observed near the Earth orbit (1 AU). In this study, we aim at investigating the relation between these disturbances and the physical properties of an ICME. Toward this end, we used an spheromak-type ICME and performed a series of three-dimensional magnetohydrodynamic (MHD) simulations with different sets of ICME parameters. The ICME is injected into the background solar wind generated from near-Sun data and interplanetary scintillation (IPS) data via an MHD-IPS tomography method. We will compare simulation results to in situ observations near the Earth and discuss how the physical properties of an ICME affect the space weather disturbances at 1 AU.

• 국제지역연구
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• 제14권1호
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• pp.3-29
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• 2010

본 논문의 목적은 해외에서 발생하는 화폐교란과 실물교란이 중간재를 수입하는 소국경제에 어떤 영향을 미치는지 알아보고, 또한 소국에서의 물가상승에 대한 명목임금연동정도가 해외경제교란이 소국경제에 전파되는 과정에 어떤 영향을 미치는지 알아보는데 있다. 이를 위해 본 논문에서는 변동환율제 하에서 자본이동이 완전하며, 합리적 기대가정 하에서 2국 2재화 모형을 채택하였다. 본 논문의 분석결과에 의하면 해외에서 발생하는 화폐교란과 실물교란은 가격효과, 해외승수효과, 자본이동을 통한 이자효과, 물가와 환율변동에 의한 상대가격효과, 그리고 실질잔고효과를 통하여 소국경제에 영향을 미치는 것으로 나타났다. 본 논문에서는 한국과 미국의 통계자료를 사용하여 실증분석을 하였다. 이를 통해 미국에서 발생하는 화폐교란과 실물교란이 한국경제에 어떤 영향을 미치는지, 그리고 한국에서의 임금연동지수가 미국에서 발생하는 경제교란이 한국경제에 전파되는 과정에 어떤 영향을 미치는지 알아보았다.

• Journal of Yeungnam Medical Science
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• 제40권4호
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• pp.394-401
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• 2023

Background: Pregnancy is associated with a number of physical, emotional, and biological changes that can exacerbate maternal psychological disturbances, such as body image concerns and depression. Sleep disturbances during pregnancy can also have adverse impacts. This study aimed to determine the prevalence of depression, sleep disturbances, and body image concerns among pregnant women. The study also examined the relationship between these factors and pregnancy-related variables, such as bad obstetric history and whether the pregnancies were unplanned. Methods: A cross-sectional study of 146 pregnant patients was conducted at a tertiary care center over 15 months. The patients were administered the Beck Depression Inventory, Pittsburgh Sleep Quality Index, and Body Image Concern Inventory questionnaires. Contingency tables, Fisher exact test, and Spearman correlation were used to identify underlying relationships. Results: The prevalence of depression was 22.6%. Although body image disturbance was noted in only 2.7% of patients, 46.6% had poor sleep quality. Poor sleep was associated with primigravida status. Bad obstetric history and unplanned pregnancy were associated with depression. Depression was found to be significantly correlated with body image disturbances and poor sleep quality. Conclusion: Psychiatric disorders were prevalent during pregnancy. This study highlights the importance of screening for depression in pregnant patients. Counselling and caregiver education can be useful for mitigating psychological disturbances. Management of pregnancies by multidisciplinary teams that include psychiatrists could be immensely useful in improving the pregnancy experiences of patients.

• Journal of Cardiovascular Imaging
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• 제30권1호
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• pp.62-75
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• 2022

BACKGROUND: Due to its location very close to the bundle of His, mitral annulus calcification (MAC) might be associated with the development of atrioventricular (AV) conduction disturbances. This study assessed the association between MAC and AV conduction disturbances identified by cardiac implantable electronic device (CIED) use and electrocardiographic parameters. The association between MAC and traditional cardiovascular risk factors was also assessed. METHODS: This cross-sectional study analyzed 14,771 participants, predominantly men aged 60-75 years, from the population-based Danish Cardiovascular Screening trial. Traditional cardiovascular risk factors were obtained. Using cardiac non-contrast computed tomography imaging, MAC scores were measured using the Agatston method and divided into absent versus present and score categories. CIED implantation data were obtained from the Danish Pacemaker and Implantable Cardioverter Defibrillator Register. A 12-lead electrocardiogram was available for 2,107 participants. Associations between MAC scores and AV conduction disturbances were assessed using multivariate regression analyses. RESULTS: MAC was present in 22.4% of the study subjects. Participants with pacemakers for an AV conduction disturbance had significantly higher MAC scores (odds ratio [OR], 1.11; 95% confidence interval [CI], 1.01-1.23) than participants without a CIED, whereas participants with a CIED for other reasons did not. Prolonged QRS-interval was significantly associated with the presence of MAC (OR, 1.45; 95% CI, 1.04-2.04), whereas prolonged PQ-interval was not. Female sex and most traditional cardiovascular risk factors were significantly associated with high MAC scores. CONCLUSIONS: MAC was associated with AV conduction disturbances, which could improve our understanding of the development of AV conduction disturbances.

• Journal of the Korean Statistical Society
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• 제23권1호
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• pp.33-38
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• 1994

The OLS-estimator of the distribance variance in the linear regression model is shown to be asymptotically unbiased when the disturbances are MA(1)-process or particular s-th autocorrelated AR(s)-process.

• Communications for Statistical Applications and Methods
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• 제1권1호
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• pp.112-118
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• 1994

The generalized least squares estimator in the linear regression model is equivalent to difference estimator irrespective of the particular form of the regressor matrix when the disturbances are generated by a seasonally autoregressive provess and autocorrelation is closed to unity.

• 한국군사과학기술학회지
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• 제11권2호
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• pp.53-65
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• 2008

This paper proposes the qualitative method for planning the operation of multi-AUVs with environmental disturbances, which is considered to be a very difficult task. In this paper we use an extension collision map as a collision free motion planner. The tool was originally developed for the multiple ground vehicles with no internal/external disturbance. In order to apply the method to a water environment where there are tides and waves, and currents, we analyze the path deviation error of AUVs caused by external disturbances. And we calculate safety margin for the collision avoidance on the extension collision map. Finally, the simulation result proves that the suggested method in this paper make multi-AUVs navigate to the goal point effectively with no collision among them.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권9호
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• pp.413-422
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• 2002

In a power plant, disturbance detection and diagnosis are massive and complex problems. Once a disturbance occurs, it can be either persistent, self cleared, cleared by the automatic controllers or propagated into another disturbance until it subsides in a new equilibrium or a stable state. In addition to the Physical complexity of the power plant structure itself, these dynamic behaviors of the disturbances further complicate the fault monitoring and diagnosis tasks. A data structure called a disturbance interrelation analysis graph(DIAG) is proposed in this paper, trying to capture, organize and better utilize the vast and interrelated knowledge required for power plant disturbance detection and diagnosis. The DIAG is a multi-layer directed AND/OR graph composed of 4 layers. Each layer includes vertices that represent components, disturbances, conditions and sensors respectively With the implementation of the DIAG, disturbances and their relationships can be conveniently represented and traced with modularized operations. All the cascaded disturbances following an initial triggering disturbance can be diagnosed in the context of that initial disturbance instead of diagnosing each of them as an individual disturbance. DIAG is applied to a typical cooling water system of a thermal power plant and its effectiveness is also demonstrated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2047-2049
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• 1997

Computers and automatic equipment are very sensitive to the disturbances such as voltage transients, voltage sag, and harmonics. These disturbances cause them to have a malfunction or fault which brings about damages and losses. UPS (uninterruptible power supply) and SPS(stand-by power supply) have been used to provide the required voltage in a critical load without disturbances. However, UPS has appreciable losses due to the operation of the inverter in full rated power at all times. SPS, although whose inverter losses are smaller than those of UPS, transfers disturbances with a short duration to the load, due to the limited reaction time. In this research, a dynamic voltage compensator, which can make up for the weakness of UPS and SPS, is proposed. The operation of the proposed system was verified by a computer simulation. A hardware scaled-model was fabricated and tested to conform the feasibility of the actual system development.