• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.48.2-48.2
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• 2010

Korean-Japanese Planet Search Program has been carried out since 2005 to search for planets around intermediate-mass giant stars (1.5-5.0 solar masses) by an international collaboration between Korean and Japanese researchers. In this program, we have been carrying out a precise radial velocity survey of about 190 G-type giant stars (6.21.9 solar masses) giant stars. These results extend the planet mass distribution of massive intermediate-mass stars to higher and lower mass region, and may further constrain substellar system formation mechanisms. We report the recent results and current status of Korean-Japanese Planet Search Program.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.65-65
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• 2019

Near-Earth objects consist of a mixture of bodies originated from outer solar system and main asteroidal belt, which are recognized as comets and near-Earth asteroids. In principal, they have orbits distinguishable by their orbital elements. It is, however, that some comets are recognized as asteroids because they could have lost the most of volatile materials in their subsurface layers. Due to their asteroidal appearances, it has been challenging to discriminate such dormant comets from a list of known asteroids. Here we propose to utilize polarimetric technique for finding such dormant comets. We thus conducted a polarimetric observations of three candidates of dormant comet nuclei, (331471) 1984 QY1, (3552) Don Quixote and (944) Hidalgo, by using the 1.6-m Pirka Telescope at the Nayoro observatory (operated by Hokkaido University, Japan). We selected these asteroids in comet-like orbits (ACOs) based on the orbital elements (i.e., the Tisserand parameter with respect to Jupiter TJ < 3). We found that 1984 QY1 has a polarimetric albedo (geometric albedo determined via polarimetry) pV = 0.16 +/- 0.06 while both Don Quixote and Hidalgo have Rc-band polarimetric albedos pR < 0.05. In accordance with the polarimetric result together with a dynamical analysis, we surmised that 1984 QY1 could be an S-type asteroid evolved into the current orbit via 3:1 mean motion resonance with Jupiter. On the contrary, the previous spectroscopic studies indicated that Don Quixote and Hidalgo are classified into D-type taxonomic group, which are typical of comet nuclei. In this presentation, we will introduce our polarimetric observations of ACOs and emphasize that polarimetry is powerful for discriminating the asteroidal and cometary origins.

• Clinics in Shoulder and Elbow
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• v.24 no.3
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• pp.156-165
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• 2021

Background: This study aimed to determine: the perspectives of the patient cohort that underwent telehealth consultation and shoulder rehabilitation during coronavirus disease 2019 (COVID-19) and the differences in the patients' perspectives with the two different telehealth video applications (apps) used in the study. Methods: This is a prospective study carried out during the COVID lockdown period of April to July 2020. Thirty consecutive patients from the orthopedics department of a tertiary institute in India underwent their first-ever session of a video app-based (Zoom or WhatsApp) telehealth consultation with shoulder rehabilitation exercises on a handheld mobile, tablet, or laptop device. After the virtual consultation, the patients were sent a validated telehealth usability questionnaire (TUQ) to evaluate their perspectives. Scores obtained from the TUQ were the primary outcome measure. Results: The study was completed by 30 patients (16 men and 14 women) with an average age of 56 years (range, 20-77 years). The patients who contacted us during the lockdown period with either a stiff shoulder or a conservatively treated shoulder fracture were included in the study. The average TUQ score was 13.6 (median, 14.5; range, 6-21) out of a maximum of 21 points. Eighty percent of the patients were satisfied and found the telehealth service useful. Use of the Zoom app scored significantly higher (median, 17; average, 15.6) than the WhatsApp app (median, 8.5; average, 9.6) (p=0.004). Conclusions: Patients who received telehealth consultation and shoulder rehabilitation were overall satisfied. Telehealth apps with advanced video calling features such as Zoom should be preferred for higher patient satisfaction.

• Clinics in Shoulder and Elbow
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• v.16 no.1
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• pp.33-39
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• 2013

Purpose: The aim of this study is to evaluate the clinical result of intra-articular fractures of the distal humerus (AO type C) in elderly osteoporotic patients treated with double tension band osteosynthesis. Materials and Methods: From January 2006 to December 2010, 10 elderly osteoporotic patients(1 male, 9 females) with intra-articular fractures of the distal humerus (AO type C) were treated with double tension band osteosynthesis. The mean age of patients at the time of surgery was 74.6(66~84) years and the mean follow-up period was 39.2(20~74) months. The fracture union and complications were assessed and the functional result was evaluated by the rating system of Jupiter et al. and the Mayo elbow performance index. Results: Bone union was achieved in all patients with no secondary displacement. The mean time for union was 16.6(13~22) weeks. The average postoperative arc of elbow flexion was 119(100~140) degrees with a mean flexion contracture of 8.5(0~15) degrees. The recovery in two patients was rated as excellent, in 7 as good, and in 1 as fair in terms of the Mayo elbow performance index with average value of 82(70~90) points. Seven patients were rated as excellent, 1 as good, and 2 as fair in terms of the rating system of Jupiter et al. Changing tension band wiring was performed in one patient as skin irritation was noticed due to tension band knots. Heterotopic ossification developed in one patient but had no symptom. Conclusion: Double tension band osteosynthesis in intra-articular fractures of distal humerus (AO type C) in elderly osteoporotic patients can provide sufficient and secure stability to allow early rehabilitation.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.47-47
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• 2003

Analytical formulae are presented to approximate the evolution of the semi major axis, the maneuver time, and the final mass fraction for low thrust orbital transfers with circular initial orbit, circular target orbit, and constant thrust directed either always along or always opposite the velocity vector. For comparison, the associated results for high-thrust transfers, i.e. the two-impulse Hohmann transfer, are summarized. All results are implemented in a computer code designed to analyze planar planetary and interplanetary space missions. This implementation yields fast and reasonably accurate approximations to trajectory performance boundaries. Consequently, the approach can provide trajectory analysis for each spacecraft configuration during the conceptual space mission design phase. As an example, a mission from Low-Earth Orbit (LEO) to Jupiter's moon Europa is analyzed.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.22.4-22.4
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• 2008

The anomalous acceleration of Pioneer-10 and Pioneer-11 is known since 1992. These spacecrafts show the unexplainable acceleration near $10^{-7}\;cm/sec^2$ in the direction to the Sun. Later the unknown acceleration of the same order was found in the motion of Ulysses in its motion from the Jupiter to Mercury, and in the motion of Galileo, NEAR, Cassini, Rosetta, and Messenger at the flybys of these spacecrafts near the Earth. The possibility of unexplainable acceleration near $10^{-7}\;cm/sec^2$ was discussed also for stellar globular clusters and for galaxies. We propose the empirical formula for taking into account this acceleration and overview the predictions of this formula at cosmological scales. Several unknown observational effects are found. One of these effects is the anomalous redshifts in the clusters of galaxies. It was known previously only for small groups of galaxies. We show the existence of anomalous redshifts in the clusters of galaxies using the spectral observations of near one million galaxies from the SLOAN 5th data release.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.351-354
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• 1996

In this paper it is explained how most of asteroids can avoid very close approach to Jupiter, to the earth for earth orbit crossing asteroids, and to Neptune for Kuiper-belt asteroids by mechanisms which work also for Neptune-Pluto system. In fact the mutual distance of the planets cannot become very small as the critical argument librates around $180^{\circ}$ because of 2:3 mean motion resonance and the argument of perihelion of Pluto librates around $90^{\circ}$. And it is found that among nearly 40 Kuiper-belt asteroids discovered in recent years $40\%$ have orbits similar to Pluto. For main-belt asteroids the distribution with respect to the semi-major axes has peculiar characteristics and the author tries to explain how their peaks and gaps are created. It is also found that $30\%$ of 80 earth orbit crossing asteroids which have minimum perihelion distances less than 1.04AU have no chance to collide with the earth. Still $30\%$ of them have a few probability to collide with the earth as they have dynamical characteristics of short-periodic comets.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.78.1-78.1
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• 2010

We obtained the spectra of 93 Planet host stars and 73 normal field stars in F, G, K type using BOES at BOAO. We measured the equivalent width of Fe and 13 elements lines using the automatic EW measurement program, TAME(Tools for Automatic Measurement of Equivalent-widths) and estimated the abundances by synth and abfind driver of MOOG code. Since the absence of planets in the normal field stars cannot be "completely" proved, this work focused on the chemical abundances and planet properties of planet host stars, which have the massive planets close to the parent star relatively. We carried out an investigation for the difference of abundances between stars with "Hot Jupiter" and normal field stars with no known planets. We examined the chemical composition of 12 elements, such as Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Co, and Ni by EW measurements, and the S abundances were estimated using synthetic spectrum.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.53.2-53.2
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• 2010

A Jupiter-family comet, 17P/Holmes, suddenly underwent a spectacular outburst on 2007 October 23, about 173 days after the perihelion passage. There has been no more outstanding comet outburst than the 17P/Holmes event since the beginning of modern astronomical observations. However, little is known about the activity of the comet before the outburst because of the accidental event. We found that 17P/Holmes appeared in the AKARI all sky survey data. It was taken on 2007 August 23, 112 days after the perihelion passage and 61 days before the outburst. The 9 micron images shows obvious coma and tail. We study the dust production rate from these images and evaluate the fractional active area. We compare these results with those of data after the outburst, and discuss the aftermass.

• Proceedings of the CALSEC Conference
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• 2003.09a
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• pp.307-312
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• 2003

업계의 배경 ■ 주 5일제 근무를 맞이한 레저와 여행산업의 시장규모 증가 ■ 2002년 이후 항공권, 호털 등을 포함한 여행상품이 정자상거래 분야에서 가장 높은 매출액을 올릴 것이라고 전망했다. (eMarketer 2002/03) ■ Biz여행 예약도 6개월 동안 2배규모로 성장 (Greenfield Online (2000/5/28)) ■ 1999년 현재 온라인 여행시장에서 항공 여행의 비중은 80％ → 2003년에는 60％ (렌터카, 호텔 예약의 비중이 높아짐) (Jupiter Communication (1999/5/17)) ■ 3/4의 인터넷 사용자가 시간표, 비행편, 가격, special deal을 탐색하기 위해 방문, 70％의 응답자가 좀더 시스템이 유연해진다면, 온라인 구매 의도 있다고 응답(가능한 여앵편, 좌석 선정 가능, 비행시의 특식 등의 욕구) (Gartner Group (2000/1/7)) ■ 75％의 응답자가 오프라인보다 온라인에서의 여행 브랜드가 중요하다고 응답함, Travel Industry Association of America (98. 99년 자료) ■ 개별여행자 (F.I.T)의 급증과 온라인을 통한 예약이 증가 (관광정보 연구원, 2002)(중략)