• 천문학회보
• /
• 제37권2호
• /
• pp.106.2-106.2
• /
• 2012

A Jupiter-family comet, 17P/Holmes, underwent an outburst on 2007 October 23. Since there has been no more dramatic comet outburst than the 17P/Holmes event in the history of modern astronomical observations, active observations were made soon after the outburst. However, little is known about the activity before the outburst because of the accidental event. In addition, since the nucleus has been veiled by the thick dust cloud by the 2007 outburst, the physical status of the nucleus was unknown. In this presentation, we investigated the contrast between before and after the outburst through the imaging observations in both optical and mid-infrared wavelengths. We thus analyzed data taken by Akari infrared telescope, Subaru 8-m telescope, University of Hawaii 2.2-m telescope and Nishi-Harima Astronomical Observatory 2-m Nayuta telescope. As the result, we found that the nucleus was significantly activated through the outburst. The surface fractional active area was 0.3% in the pre-outburst data while 10% in the past-outburst data. We expect that 17P/Holmes shows strenuous activity in the next return in 2013-2014.

• 한국군사과학기술학회지
• /
• 제19권3호
• /
• pp.311-318
• /
• 2016

This paper shows storage life estimation of next IR(infrared) flare material through accelerated degradation tests. Three temperature conditions for the accelerated degradation tests are 55, 65 and $75^{\circ}C$. Six performances of IR flare material are burning time, IR peak/continuous Intensity, total energy of near/mid-IR and color ratio, and they were measured after the tests. Storage life of the IR flare material was estimated through both analyzing the degradation data of those performances and applying distribution-based degradation models to the data. Over 30 years of storage life at $20^{\circ}C$ is estimated in terms of IR peak intensity with reliability 0.99 and confidence level 99 %. Additionally, 10 years of storage period at $21^{\circ}C$ would be equivalent to 68 days of accelerated test at $65^{\circ}C$ from the activation energy in Arrhenius model.

• Journal of Ceramic Processing Research
• /
• 제20권1호
• /
• pp.59-62
• /
• 2019

Y2O3-MgO nanocomposites are promising materials for hypersonic infrared windows and domes due to their excellent midIR transmittance and mechanical properties. In this work, influence of SPS heating rate on the microstructure, IR transmittance, and mechanical properties of Y2O3-MgO nanocomposites was investigated. It was found that the average grain size decreases with a decreasing heating rate, which can be attributed to high defect concentration by rapid heating and deformation during densification. Also, the residual porosity decreases with a decreasing heating rate, which is ascribed to the enhancement of grain boundary diffusion by a large grain-boundary area (a small grain size). Consequently, high transmittance and hardness were attained by the low heating rate. On the other hand, the mechanical strength showed little difference with the heating rate change, which is somewhat different from the general knowledge on ceramics and will be discussed in this letter.

• 한국군사과학기술학회지
• /
• 제26권1호
• /
• pp.22-30
• /
• 2023

When tracking small UAVs and drone targets in cloud clutter environments, MWIR sensors are often unable to track targets continuously. To overcome this problem, the SWIR sensor is mounted on the same gimbal. Target tracking uses sensor information fusion or selectively applies information from each sensor. In this case, parallax correction using the target distance is often used. However, it is difficult to apply the existing method to small UAVs and drone targets because the laser rangefinder's beam divergence angle is small, making it difficult to measure the distance. We propose a tracking method which needs not parallax correction of sensors. In the method, images from MWIR and SWIR sensors are captured simultaneously and a tracking error for gimbal driving is chosen by effectiveness measure. In order to prove the method, tracking performance was demonstrated for UAVs and drone targets in the real sky background using MWIR and SWIR image sensors.

• 천문학회보
• /
• 제41권2호
• /
• pp.44.1-44.1
• /
• 2016

The Sagittarius-Carina spiral arm in the Galaxy contains several massive young open clusters. We present a deep optical photometric study on the massive young open clusters in the Sagittarius-Carina arm, Westerlund 2 and the young open clusters in the ${\eta}$ Carina nebula. Westerlund 2 is a less studied starburst-type cluster in the Galaxy. An abnormal reddening law for the intracluster medium of the young starburst-type cluster Westerlund 2 is determined to be $R_{V,cl}=4.14{\pm}0.08$. The distance modulus is determined from zero-age main-sequence fitting to the reddening-corrected color-magnitude diagrams of the early-type members to be $V_0-M_V=13.9{\pm}0.14mag$. The pre-main sequence (PMS) members of Westerlund 2 are selected by identifying the optical counterparts of X-ray emission sources from the Chandra X-ray observation and mid-infrared emission sources from the Spitzer/IRAC (the Infrared Array Camera) observation. The initial mass function (IMF) shows a slightly flat slope of ${\Gamma}=-1.1{\pm}0.1$ down to $5M_{\odot}$. The age of Westerlund 2 is estimated to be. 1.5 Myr from the main-sequence turn-on luminosity and the age distribution of PMS stars. The ${\eta}$ Carina nebula is the best laboratory for the investigation of the Galactic massive stars and low-mass star formation under the influence of numerous massive stars. We have performed deep wide-field CCD photometry of stars in the ${\eta}$ Carina nebula to determine the reddening law, distance, and the IMF of the clusters in the nebula. We present VRI and $H{\alpha}$ photometry of 130,571 stars from the images obtained with the 4m telescope at Cerro Tololo Inter-American Observatory (CTIO). RV,cl in the η Carina nebula gradually decreases from the southern part (~4.5, around Trumpler 14 and Trumpler 16) to the northern part around Trumpler 15 (~3.5). Distance to the young open clusters in the ${\eta}$ Carina nebula is partly revised based on the zero-age main-sequence fitting to the reddening-corrected color-magnitude diagrams (CMDs) and the (semi-) reddening-independent CMDs. We select the PMS members and candidates by identifying the optical counterparts of X-ray sources from the Chandra Carina Complex Survey and mid-infrared excess emission stars from the Spitzer Vela-Carina survey. From the evolutionary stage of massive stars and PMS stars, we obtain that the northern young open cluster Trumpler 15 is distinctively older than the southern young open clusters, Trumpler 14 (${\leq}2.5 Myr$) and Trumpler 16 (2.5-3.5 Myr). The slopes of the IMF of Trumpler 14, Trumpler 15, and Trumpler 16 are determined to be $-1.2{\pm}0.1$, $-1.5{\pm}0.3$, and $-1.1{\pm}0.1$, respectively. Based on the RV,cl of several young open clusters determined in this work and the previous studies of our group, We suggest that higher RV,cl values are commonly found for very young open clusters with the age of < 4 Myr. We also confirm the correlation between the slope of the IMF and the surface mass density of massive stars.

• 천문학회보
• /
• 제35권1호
• /
• pp.57-57
• /
• 2010

We report the discovery of a bright mid-infrared (MIR) source with prominent crystalline silicate emission using the space telescope AKARI and Spitzer. This source, IRAS 15099-5856, has a spectacular morphology with a bright central compact source (CCS) surrounded by knots, spurs, and several extended (~4') arc-like filaments. The source is seen only in infrared at ${\geq}10{\mu}m$. The Spitzer MIR spectrum of the CCS shows prominent emission features from Mg-rich crystalline silicates and strong [Ne II] 12.88 ${\mu}m$ and several other faint ionic lines. We model the MIR spectrum as thermal emission from several independent dust components and compare their properties to those of the Herbig Be star HD 100546 which shows very similar MIR spectrum. Our molecular line observations reveal two molecular clouds around the source, but no associated dense molecular cores. We discuss two possible origins for IRAS 15099-5856; a deeply embedded massive young stellar object on the other side of the Galaxy and a disrupted, protoplanetary disk being photoevaporated by the UV radiation from the nearby O star Muzzio 10.

• 한국산학기술학회논문지
• /
• 제19권4호
• /
• pp.103-110
• /
• 2018

함정으로부터 방사되는 적외선 신호는 주로 함정의 내연 기관에 의해 발생하는 내부적 신호와 태양열에 의해 가열된 함정 표면에서 발생하는 외부적 신호로 분류된다. 이중 내부적 신호는 주요 추진 체계를 구성하는 가스 터빈 및 디젤 엔진 폐기 가스의 화학적 조성 인자들($CO_2$, $H_2O$, CO, soot)에 의해서도 영향을 받게 된다. 따라서 본 연구에서는 현재까지 국내 함정에 탑재된 가스 터빈과 디젤 엔진에서 생성되는 폐기 가스의 화학적 조성비를 조사하여 인자와 수준을 선정하였으며, 직교 배열 실험 계획법으로 폐기 가스의 화학적 조성 인자들과 구성 비율이 함정의 적외선 신호에 미치는 영향을 연구하였다. 적외선 신호 해석 프로그램을 이용하여 계산된 폐기 가스의 적외선 신호 강도는 분석의 용이성을 높이기 위해 신호 대 잡음비로 변환하여 제시하였다. 신호 분석 결과, 가스 터빈과 디젤 엔진 모두 중적외선 대역의 신호에는 $CO_2$, soot 및 $H_2O$가 주요영향인자임이 밝혀졌다. 그리고 원적외선 대역의 신호에는 $H_2O$와 $CO_2$가 주요한 영향을 미치는 인자임을 확인하였다.

• 천문학논총
• /
• 제32권1호
• /
• pp.109-111
• /
• 2017

We detected bright mid- to far-infrared emission from the helium nova V445 Puppis in the AKARI all-sky survey data taken in 2006. Assuming an optically thin condition, we decomposed the spectral energy distribution (SED) of V445 Puppis in October 2006 by model fitting and found that the SED can be explained by a combination of cold amorphous carbon (125 K and the mass of $4.5^{+6.6}_{-2.7}{\times}10^{-4}M_{\odot}$) and warm amorphous carbon (250 K and the mass of $1.8^{+1.0}_{-0.5}{\times}10^{-5}M_{\odot}$). Assuming that the former is pre-existing dust formed in the past nova outbursts and the latter is newly formed dust in December 2000's nova wind, this result suggests that the amount of dust formed around V445 Puppis in a single outburst is larger than $10^{-5}M_{\odot}$, which is larger than those in any other classical novae ever reported.

• 천문학회보
• /
• 제35권1호
• /
• pp.76.1-76.1
• /
• 2010

With advancement of infrared space telescopes during the past decade, infrared wavelength regime has been a focal point to study various properties of galaxies, such as stellar mass, dust contents and dust-hidden star formation with respect to evolution of galaxies. Polycyclic Aromatic Hydrocarbons (PAHs) have emerged as one of the most important features since these features dominate mid-infrared spectra of galaxies. These PAH features provide a great handle to calibrate star formation rates and diagnose ionized states of grains. However, PAH $3.3{\mu}m$ feature has not been studied as much as other PAH features since it is weaker than others and resides outside of Spitzer's capability. Still its calibration and characterization are important since it will be the only PAH feature accessible by JWST for high-z galaxies. AKARI mJy Unbiased Survey of Extragalactic Sources in 5MUSES (AMUSES) intends to take advantage of AKARI's capability of spectroscopy on 2 to 5 ${\mu}m$ to provide an unbiased library of 44 sample galaxies selected from a parent sample of 5MUSES, one of Spitzer legacy projects. For these 3.3mm flux limited sample galaxies whose redshifts range between 0 < z <1, AMUSES will calibrate PAH $3.3{\mu}m$ as a SFR while measuring ratios between PAH features and investigating Bra's potential as a SFR indicator. We present preliminary results of AMUSES.

• 한국임상수의학회지
• /
• 제15권2호
• /
• pp.472-475
• /
• 1998

A female Green iguana (Iguana iguana) was brought to the small animal clinic in Hannover Veterinary school because of anorexia and convulsion. Two months ago, the owner bought two iguanas, one female and one male and had to take a female to the one of local small animal clinic because she, born in 19931 didn't eat well and showed the tremor of the legs. The veterinarian suspected it to have a calcium deficiency and gave an injection of calcium and vitamin D3. But still during the last two months, the female iguana did only eat some lettuce while the other male ate lettuce, fruits and commercial cat-food ($Whiskas^{\circledR}$, Effem, Verden). It was not possible to evaluate the rations of these different "food-components". They are kept in the terrarium with water container. By palpation of the abdomen, hard thing like stone was palpated in the mid-region. The blood test wasn't carried out because of the difficulties of getting blood and because of her bad condition. It was firmly diagnosed as cystic calculus through radiography. Since the animal is in shock state already, the prognosis after surgery was bad. It was assumed to be too late to expect its surviving with the surgery carried out or without it. Cystotomy was performed in the cranial ventral paramedian incision in order to preserve the large ventral abdominal vein in the linen alba region. After two stay sutures ("holding suture" ) with 5-0 polyglactin 910 ($Vicryl^{\circledR}, Ethicon$) on the bladder, cystotomy was carried out and the stone inside was removed. Then, the bladder was closed in one-layer sutures. The abdomen was closed in simple interrupted suture with same material after the instillation of 10 ml saline solution into the abdominal cavity. The cystic calculus was in a size of $5.8{\times} 5.O{\times} 3.5 cm$. The analysis of the stone was carried out in two ways which are the infrared spectroscopy of the stone and quick analysis by $Merckognost^{\circledR}$(Diagnostica Merck, Merck). In the result of the infrared spectroscopy, the stone wee composed of 10% ammonium urate and 90% dihydrated uric acid. This iguana wasn't able to survive.n't able to survive.