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        검색결과 29

        1.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        서로 다른 숙기를 가진 여섯 개의 자두 품종을 이용하여 과실 발육 단계에 따른 주요 과실 특성의 변 화를 조사하였다. 자두 과실의 산도는 유과기에 가장 높은 수치를 보였다가 과실의 발육이 급속하게 이 루어지는 시기를 기점으로 감소되고 이후 수확기까지 점진적으로 감소하였다. 가용성 고형물 함량은 산 도와 거의 반대로 증가하는 경향을 보였고 숙기가 빠른 품종 일수록 보다 빠른 시기에 변화가 나타났 다. 수확기에 측정 된 산도와 가용성 당함량의 축적량은 품종에 따라 차이가 있어 품종 특이적인 변이 가 있음을 확인하였다. 과실의 발육동안 유리당과 유기산의 조성변화와 수확기에 조사된 총 유리당과 유기산 함량의 검정 결과에서도 품종에 따른 변이를 관찰하였다. 이를 통하여 과실의 발육과정 중 일어 나는 품종 특이적 과실특성의 다양한 변화 양상이 결과적으로 수확기 품종 간 과실품질에 있어서 변이 를 일으키는 주요한 요인으로 작용하고 있음을 간접적으로 확인하였다. 과실의 특성과 관련된 형질들의 값을 이용하여 주성분 분석을 실시한 결과, 본 실험에 이용된 여섯 개의 품종을 대조적인 과실 특성을 가진 세 개의 그룹으로 나눌 수가 있었다. 본 연구를 통해서 밝혀진 과실발육 기간 동안과 수확기에 대 조적인 과실특성을 가진 품종들을 이용한 추가적인 생리 및 육종 연구들은 고품질 자두의 육종에 도움 을 줄 수 있을 것이다.
        4,300원
        2.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We investigated the period variation for 79 eclipsing binary systems using 20 years (1990-2009) of EROS, Macho, and OGLE survey observations. We discovered 9 apsidal motions, 8 mass transfers, 5 period increasing and decreasing systems, 12 light-travel-time effects, 5 eccentric systems and 40 other systems showing no period variations. We select 3 representative eclipsing binary systems; EROS 1052 for apsidal motion, EROS 1056 for mass transfer, and EROS 1037 for the light-travel-time effect. We determine the period variation rate (dP/dt), orbital parameters of the 3rd body (e3, ω3, f(m3), P3, T3), apsidal motion parameters (dω/dt, U, Ps, Pa, e) and apsidal motion period by analyzing the light curves and O-C diagrams.
        3,000원
        3.
        2014.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present the rst period variation study for the Algol eclipsing binary V346 Cyg by constructing the (O-C) residual diagram using all the available precise minima times. We conclude that the period variation can be explained by a sine{like variation due to the presence of a third body orbiting the binary in about 68:89  4:69 years, together with a long-term orbital period decrease (dP=dt = -1:23 x 10-7day=yr) that can be interpreted to be due to slow mass loss from the δ-Scuti primary component. The sinusoidal variation may also be explained by using the the Applegate (1992) mechanism involving cyclic magnetic activity due to star-spots on the secondary component. The present preliminary solution needs more precise photometric observations to be con rmed.
        4,000원
        4.
        2013.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We discuss the orbital period changes of the Algol semi-detached eclipsing binary DI Peg by con- structing the (O−C) residual diagram via using all the available precise minima times. We conclude that the period variation can be explained by a sine–like variation due to the presence of a third body orbiting the binary, together with a long-term orbital period increase (dP/dt = 0.17 sec/century) that can be in- terpreted to be due to mass transfer from the evolved secondary component (of rate 1.52×10−8M⊙/yr) to the primary one. The detected low-mass third body (M3 min. = 0.22±0.0006 M⊙) is responsible for a periodic variation of about 55 years light time effect. We have determined the orbital parameters of the third component which show a considerable eccentricity e3 = 0.77± 0.07 together with a longitude of periastron ω3 = 300° ± 10°.
        4,000원
        5.
        2011.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The photometric light curves of the W-type W UMa eclipsing contact binary system BB Pegasi have been found to be extremely asymmetric over all the observed 63 years in all wavelengths UBVR. The light curves have been characterized by occultation primary minima. Hence, the morphology of these light curves has been studied in view of these different asymmetric degrees. The system shows a distinct O'Connell effect, as well as depth variation. A 22.96 years of stellar dark spots cycle has been determined for the system. Almost the same cycle (22.78 yr) has been found for the depth variation of MinI and MinII. We also present an analysis of mid-eclipse time measurements of BB Peg. The analysis indicates a period decrement of 5.62X 10-8 day/yr, which can be interpreted in terms of mass transfer at a rate of -4.38 X 10-8M⊙/yr, from the more to the less massive component. The O - C diagram shows a damping sine wave covering two different cycles of 17.0 yr and 12.87 yr with amplitudes equal to 0.0071 and 0.0013 day, respectively. These unequal durations show a non-periodicity which may be explained as a result of magnetic activity cycling variations due to star spots. The obtained characteristics are consistent with similar chromospherically active stars, when applying the Applegate's (1992) mechanism.
        4,300원
        6.
        2010.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present an analysis of the measurements of mid-eclipse times of V839 Oph, collected from literature sources. Our analysis indicates a period increase of 3.2 X 10-7 day/yr. This period increase of V839 Oph can be interpreted in terms of mass transfer of rate 1.76 X 10-7⊙/yr, from the less to the more massive component. The O - C diagram shows a damping sine wave covering two different complete cycles of 36.73 yr and 19.93 yr with amplitudes approximately equal to 0.0080 and 0.0043 day, respectively. The third cycle has to be expected to cover about 13.5 years with lower amplitude than those of the former two cycles. These unequal duration cycles show a non periodicity which may be explained as resulting from either the presence of a tertiary component to the system or cyclic magnetic activity variations due to star spots. For the later mechanism, the obtained characteristics are consistent when applying Applegate (1992) mechanism.
        4,200원
        8.
        2006.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        A period study of the semi-detached eclipsing binary system W Delphini based on the extensive series of minimum timings covering more than a century(109 years) indicates a cyclic(O-C) variation of the system. This variation can be explained as due either to (1) stellar magnetic activity cycles of the cool subgiant G5 secondary component of the binary with a subsurface magnetic field equals to 3 kG, or (2) a long-term orbital period increases with a rate of 1.68 × 10-8 day/cycle caused by a mass transfer rate of 4.9 × 10-8M⊙yr-1 from the less to more massive component modulated by a light time effect due to a hypothetical third body with period of 53.4±1.06 years. The former explanation is more recommended than the later one since the obtained third body mass value(M3=1.58 M⊙) is quite large but it can not manifest itself observationally and also it cannot be a white dwarf. In the contrary, from the magnetic activity point of view, the obtained characteristics are in good consistent when applying Applegate(1992) mechanism. However, further precise photometric and CCD observations for minima timings with brightness determinations are needed to confirm the present solution.
        4,000원
        9.
        2005.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        아시아의 동안에 위치한 한반도는 수리적, 지리적 요인에 의해 지역에 따라 강수현상 및 탁월 일기의 다소와 그 계절변화가 크다. 이러한 탁월한 날씨의 특징은 한국의 하계의 강수출현율과 그 순변화에 잘 반영되고 있다. 본 논문은 한국의 78개 관측지점의 하계강수량(1991~2003)의 순별 평균값에 대해 주성분분석법을 응용하여 하계강수량의 순변화형을 추출하고, 그의 공간스케일과 강수량의 다소에 따라 강수지역구분을 한 것이다. 주성분 분석에 의해 추출된 주성분 벡터와 진폭계수(Rs)에 따라 하계 강수량 순변화의 전형적인 특징은 두 개의 순변화형으로 표현되며 그 누적기여율은 64.3%이다. 또한 한국의 하계 강수량의 순변화형은 A~K형까지 9개가 추출되었고, 강수지역은 17개형으로 분류되었다.
        4,300원
        10.
        2005.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present a period analysis of the well known β Lyrae type eclipsing binary GO Cyg (P= 0d .7177). Several new times of minimum light, recorded photoelectrically, have been gathered. Analysis of all available eclipse timings of GO Cyg has confirmed a significant period increase with rate of 2.52 X 10-10day / cycle, also new period has been estimated. New linear and quadratic ephemerides have been calculated for the system.
        3,000원
        13.
        1997.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A variation of free sugar and free amino acid contents of apples during the ripening period was determined by HPLC and amino acid analyzer. The research results are as followes: Fructose, glucose and sucrose were present in the apples. The contents of fructose was the highest, followed by the order of sucrose and glucose. The contents of total sugar in Red fuji was relatively higher than that of Fuji. During the ripening period, the contents of fructose increased conspicuously for the harvesting season and then it decreased gradually. The contents of glucose increased gradually for the harvesting season and then it somewhat decreased. The contents of sucrose increased continually, while, the contents of total free sugar reached the maximum for the harvesting season and then it decreased gradually. A variation in the contents of free amino acid and composition during the ripening period didn't make a significant difference. The major free amino acid of the apples was in the order of aspartic acid, serine, threonine, glutamic acid, histidine, arginine, and alanine. During the ripening period, aspartic acid, threonin, serine, alanine, histidine, and arginine increased gradually. Especially, alanine, histidine, and arginine increased remarkably after the the harvesting season. Glutamic acid, valine, isoleucine, and leucine didn't show much change. The contents of total amino acid increased little by little as the apples ripened, dranstically increased during the harvesting season and slowly increased or slightly decreased after the harvesting seasom.
        4,000원
        14.
        1994.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We have detected a SiO maser line (v=1, J=2- 1) for 15 stars out of about 80 long period variables in the wide range of period. No new sources are detected; all detected sources are variables with period longer than 300 days; no evidence is found that the dust grains in the outer envelope have influenced on this line. The time variation of this maser line for 7 stars, T Cep, μ Cep, U Her, R Leo, R Lmi, U Ori, and R Ser is observed and compared with optical light curve at the same epoch of maser observation. No universial relation between the time variation and the optical light curve is found. It implies that the radiation from a central star does not much play an important role for the direct pumping of the SiO maser line.
        4,600원
        15.
        1993.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In principle, both radiation and collision are capable of pumping the SiO masers. In order to check which pumping mechanism is more efficient, we calculated the rate equation for our model including the 3 vibrational slates with 7 rotational states of each vibrational slate. Through solving the radiative transfer equation with the Sovolev approximation, we estimated the line profiles from an expanding envelope for several transitions. It is found that the collision works more efficiently than the radiation for the inversion in excited vibrational stales. However in an expanding envelope model we could not get the strong line intensity as observed one because the population inversion is possible only in a small restricted region. For the enough population inversion to get type observed maser intensity. the number density of SiO and hydrogen molecules should be up to about 2×105cm−3 2×105cm−3 and 1×109cm−3 1×109cm−3 , respectively, and the inversion should be occured in the region of no Jess than 11014cm.
        5,800원
        16.
        1989.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        사초용유채의 품종선별선급실험과 유채용유채와 사초용유채품종들 간에 있어서 생산성과 영양가치를 비교한 실험에서 사초용유채 도인품종중 우리나라 남부지역의 특성에 적합한 품종으로 Velox가 사초생산성 및 영양가치면에서 가장 유망하다고 생각되었다. 따라서 Velox를 공시하여 고립적배와 실행群落培 사이에 생산성과 영양가치에 있어서 어떤 차이가 있는가를 비교하였으며 또한 생육과정중의 영양가치의 변화를 조사하였는데 그 결과를 요약하면 다음과 같다. 1. 수당 생산
        4,000원
        19.
        2018.06 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        El Niño is the largest fluctuation in the climate system, and it can lead to effects influencing humans all over the world. An El Niño occurs when sea surface temperatures in the central and eastern tropical Pacific Ocean become substantially higher than average. We investigated the change in sea surface temperature in the Pacific Ocean during the El Niño period of 2015 and 2016 using the advanced very-high-resolution radiometer (AVHRR) of NOAA Satellites. We calculated anomalies of the Pacific equatorial sea surface temperature for the normal period of 1981–2010 to identify the variation of the 2015 El Niño and warm water area. Generally, the warm water in the western tropical Pacific Ocean shifts eastward along the equator toward the coast of South America during an El Niño period. However, we identified an additional warm water region in the Niño 1+2 and Peru coastal area. This indicates that there are other factors that increase the sea surface temperature. In the future, we will study the heat coming from the bottom of the sea to understand the origin of the heat transport of the Pacific Ocean.
        20.
        2017.05 KCI 등재 서비스 종료(열람 제한)
        Meteorological characteristics related to variations in ozone (O3) concentrations in the Korean peninsula before, during, and after Typhoon Talas (1112) were analyzed using both observation data and numerical modeling. This case study takes into account a high O3 episode (e.g., a daily maximum of ≥90 ppb) without rainfall. Before the typhoon period, high O3 concentrations in the study areas (e.g., Daejeon, Daegu, and Busan) resulted from the combined effects of stable atmospheric conditions with high temperature under a migratory anticyclone (including subsiding air), and wind convergence due to a change in direction caused by the typhoon. The O3 concentrations during the typhoon period decreased around the study area due to very weak photochemical activity under increased cloud cover and active vertical dispersion under a low pressure system. However, the maximum O3 concentrations during this period were somewhat high (similar to those in the normal period extraneous to the typhoon), possibly because of the relatively slow photochemical loss of O3 by a H2O + O(1D) reaction resulting from the low air temperature and low relative humidity. The lowest O3 concentrations during the typhoon period were relatively high compared to the period before and after the typhoon, mainly due to the transport effect resulting from the strong nocturnal winds caused by the typhoon. In addition, the O3 increase observed at night in Daegu and Busan was primarily caused by local wind conditions (e.g., mountain winds) and atmospheric stagnation in the wind convergence zone around inland mountains and valleys.
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