• Archives of Plastic Surgery
• /
• v.37 no.3
• /
• pp.309-312
• /
• 2010

Purpose: An osteoma is one of the common benign tumors that penetrate the nasal portion, paranasal and frontal sinus. This tumor is mostly found by radiation test accidentally, however in rare cases; it can be found to be touched or with its symptoms as the tumor grows. We report this case since we found and healed the benign tumor which was affecting orbit and the both sides of fronal sinus. Methods: A 19 year old female patient visited to our hospital due to the mass on her forehead. The symptoms began 3 years ago but no special symptom was found except for touchable mass. She was diagnosed as the osteoma of superior orbital parts and both sides of frontal sinus using X-ray and CT scanning. The size of osteoma was $5{\times}2.5{\times}3.5\;cm$ and indicated the patterns penetrated to the right side of orbital region. The osteoma excision was conducted with coronal incision and wide area of defect part in frontal sinus and superior orbital part were reconstructed by cranial bone graft and resorbable fixation plates. Results: The patient recovered without any postoperative infections or complications and symptoms. Dysaesthesia was found on her frontal area but improved in 1 month after the surgery. Conclusion: The occurrences of osteoma in frontal sinus are rare and can be treated with conservative methods if there are no infections and symptoms. We report this case since we found the benign tumor, which was affecting orbit and the both sides of fronal sinus and healed it with coronal resectomy without any complications.

• Journal of Aerospace System Engineering
• /
• v.17 no.2
• /
• pp.94-102
• /
• 2023

A nylon wire holding and release mechanism (HRM) has been widely used for deployable applications of CubeSat owing to its simplicity and low cost. In general, structural safety of solar panel with an HRM has been designed by performing structural analysis under a launch environment. However, previous studies have not performed thermal analysis for HRM in an on-orbit environment. In this study, Launch and Early Orbit Phase (LEOP) thermal analysis was performed to evaluate thermal stability of the mechanism in the orbital thermal environment of the pogo pin-based HRM applied to CubeSat. In addition, the effectiveness of the thermal design and performance of the pogo pin-based HRM were verified through a thermal vacuum test.

• Journal of the Korean Society of Earth Science Education
• /
• v.9 no.3
• /
• pp.323-340
• /
• 2016

The purpose of this study is to investigate the effect of observing material on the phase change of moon considering the orbits of earth and moon for elementary school students. For this study, the material which shows the orbit of moon tilted at $5^{\circ}$ with the orbit of earth is developed. 110 6th grade students in an elementary school are sampled. They are divided into the experimental group and the control group. The lessons using the material developed in this study are implemented to the experimental group, and the lessons using the material proposed in ordinary textbook are implemented to the control group. The pre, post, delayed concept tests on the phase change of moon are administered to the students of the experimental group and the control group, and semi-structured interviews are conducted for each concept level. According to students' responses, the concept levels are divided into 'Phase recognition', 'Space viewpoint', 'Earth viewpoint', and 'No recognition'. The experimental group and the control group are homogeneous in the pre-test. The result of this study shows that the experimental group gains significantly more scores than the control group in the post and delayed tests. Also, in the post and delayed tests, more students of the experimental group are in the highest level 'Phase recognition' than the control group. Finally, students of the experimental group who were in the 'Phase recognition' and 'Space viewpoint' explain more scientifically than the students of the control group. Therefore the results of this study show that the observing material on the phase change of moon considering the orbits of earth and moon is effective.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.12
• /
• pp.945-952
• /
• 2020

In this study, the effects of Low Earth Orbit(LEO) environments on the degradation behavior of epoxy nano silica composite materials were investigated. The nanocomposite materials containing silica particles in different weight ratios of 10% and 18% were prepared and degraded in a LEO simulator to compare with the neat epoxy cases. Thermogravimetric analysis (TGA) was performed on the degraded nanocomposites and the activation energies were calculated by Friedman method, Flynn-Wall-Ozawa (FWO) method, Kissinger method, and DAEM (Distributed Activation Energy Method) based on the iso-conversional method. As the results, for the neat epoxy sample cases, it was found that the average activation energy was increased as the degradation was progressed. When the nano particles were mixed, however, the energy increased to the 15 environmental test cycles, and decreased afterwards, meaning that the particle mixture contributed adversely to the thermal degradation. Discussions on the results of the different calculation methods were also given.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.108-111
• /
• 2017

High performance upper stage engine is necessary for space launch vehicles of geostationary orbit, and staged combustion cycle engine is suitable due to high specific impulse. Technology demonstration model for 9 tonf class staged combustion cycle engine, which is consisted of turbopump, preburner, combustion chamber and supply system, was assembled, and hot-firing test was conducted for three seconds in Upper-stage Engine Test Facility of Naro Space Center. Ignition, combustion and shut down of engine system was performed normally, and its performance parameters were evaluated.

• Aerospace Engineering and Technology
• /
• v.11 no.2
• /
• pp.49-56
• /
• 2012

LEO Satellite performs the operations and missions by FSW(Flight Software) after separation from a launch vehicle. Many of the operations by FSW are automatically conducted by the algorithms of FSW. In the case of the IAC(Initial Activation and Checkout) operations, a mission scheduling, an orbit transition, etc, however, a decision and a control of the satellite operators or manufacturers are required in order to operate the satellite safely. For this, the wireless communication channel between a satellite and a ground station should be prepared to receive telemetries and to transmit tele-commands for controlling FSW properly. Therefore, the verification of the interface between KOMPSAT-3 and a ground station is essential. This verification test is named the satellite end-to-end test. In this paper, we show the design process of the satellite end-to-end test and test results.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.11 no.1
• /
• pp.12-17
• /
• 2018

This study describes the design and implementation of Antenna for Digital Satellite Communication. The Antenna unit for SHF band consists of Reflector, Septom Polarizer, Feed Horn and Support Frame etc. Thought analysis of space environment before production, the possibility of the malfunction of equipment minimized and we designed a reliable Antenna through simulation for vibration and thermal analysis generated during the launch, and compared pre-simulation of main performance results to test results about main performances of Antenna after production. After fabricating the antenna, the maximum gain of the antenna main beam is 36.5dBi, which satisfies the requirement of 35dBi or more, and it also satisfies the requirement of -20dB for return loss of less than -24dB. Also, the isolation of the transmission and reception of the antenna is -22.6dB or less, which satisfies the requirement of -20dB or less. The antenna for digital satellite communication described in this paper can be used in the satellite field of geostationary earth orbit and low earth orbit requiring high reliability in the future.

• Korean Journal of Remote Sensing
• /
• v.37 no.5_1
• /
• pp.927-938
• /
• 2021

A similar magnitude of non-gravitational perturbations are act on the formation flying low earth orbit satellites with a certain time difference. Using this temporal correlation, the non-gravity acceleration of the low earth orbiting satellites can be transferred for the othersatellites. There is a period in which the accelerometer data of one satellite is unavailable for GRACE and GRACE-FO satellites. In this case, the accelerometer data transplant method described above is officially used to recover the accelerometer data at the Jet Propulsion Laboratory (JPL). In this paper, we proposed a model for predicting accelerometer data of formation flying low earth orbit satellites using a neural network (NN) model to improve the estimation accuracy of the transplant method. Although the transplant method cannot reflect the satellite's position and space environmental factors, the NN model can use them as model inputs to increase the prediction accuracy. A prediction test of an accelerometer data using NN model was performed for one month, and the prediction accuracy was compared with the transplant method. The NN model outperformsthe transplant method with 55.0% and 40.1% error reduction in the along-track and radial directions, respectively.

• Proceedings of the KSRS Conference
• /
• 2007.10a
• /
• pp.45-48
• /
• 2007

COMS satellite is a multipurpose satellite in the geostationary orbit, which accommodates multiple payloads of Meteorological Imager, Geostationary Ocean Color Imager and Ka band Satellite Communication Payload in a single spacecraft platform. In this paper, current status of Korea's first geostationary Communication, Ocean and Meteorological Satellte(COMS) program development is introduced. The satellite platform is based on the Astrium EUROSTAR 3000 communication satellite, but creatively combined with MARS Express satellite platform to accommodate three different payloads efficiently for COMS. The system design difficulties are in the different kinds of payload mission requirements of communication and remote sensing purposes and how to combine them into a single satellite to meet the overall satellite requirements. The COMS satellite critical design has been accomplished successfully to meet three different mission payloads. The platform is in Korea, KARI facility for the system integration and test. The expected launch target of COMS satellite is scheduled in June 2009.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.235-242
• /
• 2008

An innovative Panel ExTension SATellite(PETSAT) and propulsion system for PETSAT, are presented in this paper. First, we outline what PETSAT is. Next, based on PETSAT ethos, design policy of the propulsion system is provided. According to the policy, we designed propulsion system and concretely estimated and assembled mono-propellant and bi-propellant systems, and it indicated that mono-propellant propulsion with 50-60 seconds of specific impulse and 1 N of thrust is probable. In the case of bi-propellant, 120-150 seconds of specific impulse is valid even based on the design policy. We conducted captive tests of mono-propellant and bi-propellant propulsions with a breadboard model of propulsion system for PETSAT, and obtained good operations and performances. Based on the test results, we designed and manufactured flight model propulsion system for PETSAT. We are planning to demonstrate it in SOHLA-2L project progressed by the Space Oriented Higashiosaka Leading Association(SOHLA). SOHLA-2L will be the first on-orbit demonstrator of PETSAT in 2008.