• 천문학회보
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• 제38권2호
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• pp.65.2-65.2
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• 2013

We present a study of outflows on 24 embedded young stellar objects (YSOs), which are selected from the sources of the Dust, Ice, and Gas in Time (DIGIT) Herschel key program. Molecular outflow activity, which is believed to have strong dependence on accretion process, is the most powerful in the early embedded phase of star formation and declines as the central protostars evolve to the main sequence stage. In order to study the relation between the CO outflow observed in low J transitions and the properties of protostars, we mapped the CO outows of the selected targets in J = 1-0 and J = 2-1 lines with the 14-m TRAO telescope and the 6-m SRAO telescope, respectively. We estimate CO outflow momentum fluxes (Fco) and compare with bolometric luminosity, Lbol, bolometric temperature, Tbol, and the FIR molecular line luminosities of CO, $H_2O$, OH and [O I], which were detected by the Herschel-PACS observations. We found that $Fco_{1-0}$ is greater than $Fco_{2-1}$, and the mean ratio is about 2. L1455-IRS3 and IRAM04191 have high Fco in spite of low $L_{bol}$. The well known correlation between Fco and $L_{bol}$. is not very evident from all our samples. However, Fco and $L_{bol}$. show a rather strong correlation if L1455-IRS3 and IRAM04191 are excluded. Fco shows little correlation with FIR line luminosities of individual species, while the total FIR line luminosity summed over CO, $H_2O$, OH, and [OI] lines seems to have some correlation. In addition, we report 22 GHz $H_2O$, and 44 GHz CH3OH maser line detections in four sources out of the 24 YSOs.

• 한국농림기상학회:학술대회논문집
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• 한국농림기상학회 2018년도 하계 학술발표초록집
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• pp.109-110
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• 2018

• 천문학회지
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• 제14권1호
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• pp.43-49
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• 1981

Making use of log $T_{eff}-M_{bol}$ diagram along with Stohers' stellar evolutionary tracks (1972), we estimated the masses of 107 O stars in HII regions, which were selected from the catalogue compiled by Goy (1973). It is found that our estimated masses of O stars range from $20M_{\odot}\;to\;120M_{\odot}$ and about 20% of them falls in the mass range above $60M_{\odot}$ in agreement with earlier findings of Conti et al. (1975).

• Korean Chemical Engineering Research
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• 제59권3호
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• pp.393-398
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• 2021

리튬이온전지의 성능을 최적화하기 위해서는 여러 열화 요소들을 고려한 성능 예측 모델링 기술이 필요하다. 본 연구에서는 리튬이온전지의 사이클 노화로 인한 방전 거동 및 사이클 수명 변화를 수학적으로 모델링하였다. 모델링의 신뢰성을 검증하기 위해 0.25C로 사이클 시험을 진행했으며, 30 사이클 간격으로 진행한 RPT (Reference performance test)를 통해 전기적 거동을 파악하였다. 기존의 리튬이온전지의 사이클 수명 예측 모델에 BOL (Beginning of life)에서 일어나는 현상 중 하나인 Break-in 메커니즘을 반영하여 수명예측 정확도를 개선시켰다. 모델에 근거하여 예측된 사이클 수명 변화는 실제 시험 결과와 잘 일치하였다.

• 산업공학
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• 제19권3호
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• pp.181-189
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• 2006

This study introduces an overall framework for RFID applications in product lifecycle management(PLM). PLM is a new strategic approach to manage product related information efficiently over the whole product lifecycle. Recently, with emerging technologies such as radio frequency identification(RFID), global positioning system(GPS), and wireless communication, PLM provides a new environment that enables us to gather and analyze product lifecycle information, and make decisions on several issues without spatial and temporal constrains. However, a PLM system just provides us with new opportunities to gain the PLM system, first and foremost, it is necessary to look into its overall framework in the viewpoint of hardware, software, and business model. For this purpose, in this study, first, we introduce the technical framework of the new PLM environment with the concept of extended RFID system, called product embedded information device(PEID). Then, for each lifecycle phase such as beginning of life(BOL), middle of life(MOL), and end of life(EOL), we explore several research problems that become highlighted under the new PLM environment.

• Fisheries and Aquatic Sciences
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• 제17권1호
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• pp.129-136
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• 2014

Using the criteria of previous study, we analyzed the morphological characters of 66 specimens of the Sebastes pachycephalus complex collected from Korea between 2008 and 2013. As a result, the 37 specimens were identified as Sebastes nudus, and the remaining specimens as Sebastes pachycephalus. Sebastes nudus is characterized by the absence of scales below the base of the dorsal fin spines; the absence of dark spots on the dorsal, anal, and caudal fins; and the presence of distinct yellow or brownish-red markings on the dorsum (when fresh). The most similar species S. pachycephalus differs from S. nudus in having minute scales below the base of the dorsal fin spines. We propose the new Korean name "Hwang-jeom-gae-bol-rak" for S. nudus, and redescribe S. pachycephalus.

• Nuclear Engineering and Technology
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• 제52권3호
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• pp.469-476
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• 2020

Research reactors in-core experimental facilities are designed to provide the highest steady state flux for user's irradiation requirements. However, fuel conversion from highly enriched uranium (HEU) to low enriched uranium (LEU) driven by the ongoing effort to diminish proliferation risk, will impact reactor physics parameters. Preserving the reactor capability to produce the needed flux to perform its intended research functions, determines the conversion feasibility. This study investigates the neutron flux in the central experimental facility of two material test reactors (MTR), the IAEA generic10 MW benchmark reactor and the 22 MW s Egyptian Test and Research Reactor (ETRR-2). A 3D full core model with three uranium enrichment of 93%, 45%, and 20% was constructed utilizing the OpenMC particle transport Monte Carlo code. Neutronics calculations were performed for fresh fuel, the beginning of life cycle (BOL) and end of life cycle (EOL) for each of the three enrichments for both the IAEA 10 MW generic reactor and core 1/98 of the ETRR-2 reactor. Criticality calculations of the effective multiplication factor (K_eff) were executed for each of the twelve cases; results show a reasonable agreement with published benchmark values for both reactors. The thermal, epithermal and fast neutron fluxes were tallied across the core, utilizing the mesh tally capability of the code and are presented here. The axial flux in the central experimental facility was tallied at 1 cm intervals, for each of the cases; results for IAEA 10 MW show a maximum reduction of 14.32% in the thermal flux of LEU to that of the HEU, at EOL. The reduction of the thermal flux for fresh fuel was between 5.81% and 9.62%, with an average drop of 8.1%. At the BOL the thermal flux showed a larger reduction range of 6.92%-13.58% with an average drop of 10.73%. Furthermore, the fission reaction rate was calculated, results showed an increase in the peak fission rate of the LEU case compared to the HEU case. Results for the ETRR-2 reactor show an average increase of 62.31% in the thermal flux of LEU to that of the HEU due to the effect of spectrum hardening. The fission rate density increased with enrichment, resulting in 34% maximum increase in the HEU case compared to the LEU case at the assemblies surrounding the flux trap.

• 한국항공우주학회지
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• 제49권12호
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• pp.1019-1025
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• 2021

거의 모든 우주 환경에서 태양전지 열화는 양성자에 의해 좌우된다. 정지궤도는 전자 방사선 벨트에 위치하지만 태양 이벤트에서 방출된 양성자는 여전히 태양전지 열화의 주된 요소이다. 2010년 6월 26일 천리안 1호가 발사된 이후로, 2012년 1월 23일에서 29일 그리고 2012년 3월 7일에서 14일에 다년 평균 관측 수준의 약 30배 이상의 플루언스를 갖는 양성자 이벤트가 관측되었다. 본 논문은 2012년 1월과 3월에 발생한 태양 양성자 이벤트에 의해 감시 셀의 개방회로 전압(Voc)과 션트 스위치에 연결된 한 섹션의 단락회로 전류(Isc)에 대한 태양전지 열화에 대해 연구한다. 태양전지의 성능을 평가하기 위해 전압과 전류의 비행 데이터는 온도, 지구-태양 거리, 태양 각도로 보정한 후 임무 초기 태양전지 특성과 비교한다. Voc 전압은 2012년 1월 양성자 이벤트 이전과 비교하여 2012년 3월 양성자 이벤트 이후에 약 23.6mV 감소되었다. 감소된 Voc 전압은 임무 초기값 2575mV에 대해 1% 미만이다. Isc 전류는 예상대로 2012년 3월 양성자 이벤트에서 무시할 정도로 감소되었다.

• 재활복지공학회논문지
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• 제9권1호
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• pp.45-51
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• 2015

본 연구에서는 3차원 척추 안정화 운동이 고령자의 체간 근력 및 신체 구성 변화에 미치는 효과에 대해 검증하고자 하였다. 피험자는 건강한 65세 이상 고령자 40명(훈련군 20명, 대조군 20명)으로 구성하였다. 피험자는 실험 전 후 척추안정화 훈련 장치를 이용하여 8가지 방향에 대한 근력 평가를 수행하였다. 또한 체성분 분석기를 이용하여 신체 구성 변화에 대한 평가를 수행하였다. 훈련군은 척추 안정화 훈련 시스템에서 방향성 훈련(F, FOR, R, BOR, B, BOL, L, FOL)을 제공하였으며, 탄력 밴드 운동, 근력 강화 체조, 걷기 운동으로 구성된 복합운동을 30분간 수행하였다. 대조군은 척추 안정화 운동을 제외한 복합운동을 실시하였으며, 모든 훈련은 주 3회, 총 8주간 실시하였다. 그 결과 훈련군은 체간 근력이 실험 전 79.9점에서 8주 후 85.6점으로 유의하게 증가하는 결과를 보였으며, 신체구성에서도 체중 감소, 체지방 감소, BMI 지수 감소 등의 결과를 나타내었다. 반면, 대조군의 경우 체간 근력의 변화는 없었지만 골격근량 증가, 체지방 감소 등의 운동 효과를 나타내었다. 이러한 결과는 척추 안정화 운동이 고령자의 체간 근력 및 신체구성 발달을 유도하여 고령자의 비만 및 낙상 예방에 도움이 될 것으로 판단된다. 향후 이러한 데이터를 기반으로 척추 안정화 훈련기기와 복합운동을 조합하여 고령자들에게 효과적인 재활 운동 프로그램 개발에 응용될 수 있을 것으로 판단된다.

• 천문학회보
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• 제36권1호
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• pp.83.1-83.1
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• 2011

We report multi-epoch, simultaneous 22 GHz water and 44 GHz Class I methanol maser line survey towards 180 intermediate-mass young stellar objects, including 14 Class 0, 19 Class I objects, and 147 Herbig Ae/Be stars. We detected $H_2O$ and $CH_3OH$ maser emission towards 16 (9%) and 10 (6%) sources with one new $H_2O$ and six new $CH_3OH$ maser sources. The detection rates of both masers rapidly decrease as the central (proto)stars evolve, which is contrary to the trends in high-mass star-forming regions. This suggests that the excitations of the two masers are closely related to the evolutionary stage of the central (proto)stars and the circumstellar environments. $H_2O$ maser velocities deviate on average 9 km s-1 from the ambient gas velocities whereas $CH_3OH$ maser velocities well match with. For both maser emissions, large velocity difference (${\mid}v_{H2O}-v_{sys}{\mid}\;>\; 10kms^{-1}\; and\;{\mid}v_{CH3OH}-v_{sys}{\mid}\;>\;1kms^{-1}$) is mostly confined to Class 0 objects. The formation and disappearance of $H_2O$ maser lines are frequent and the integrated intensities of them change up to two orders of magnitude. In contrast, $CH_3OH$ maser lines usually show no significant change in the intensity, shape, and velocity. This consistent with the previous suggestion that $H_2O$ maser emission originates from the base of an outflow while 44 GHz Class I $CH_3OH$ maser emission arises from the interaction region of the outflow with the ambient gas. The isotropic maser luminosities are well correlated with the bolometric luminosities of the central the objects. The fitted relations are $L_{H2O}=1.71{\ast}10^{-9}(L_{bol})^{0.97}$ and $L_{CH3OH}=1.71{\ast}10^{-10}(L_{bol})^{1.22}$.