• Korean Journal of Mathematics
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• 제24권1호
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• pp.1-13
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• 2016

This paper shows that the solutions to the perturbed functional dierential system $$y^{\prime}=f(t,y)+{\int_{t_0}^{t}}g(s,y(s),Ty(s))ds$$ have uniformly Lipschitz stability and asymptotic property. To sRhow these properties, we impose conditions on the perturbed part ${\int_{t_0}^{t}}g(s,y(s),Ty(s))ds$ and the fundamental matrix of the unperturbed system $y^{\prime}=f(t,y)$.

• 대한디지털의료영상학회논문지
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• 제14권1호
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• pp.7-12
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• 2012

The purpose of this study was to examine usefulness of 3T equipment-based time-of-flight magnetic resonance angiography (3T-TOF MRA) by comparing standard technique (ST) with high resolution technique (HRT) in evaluation of cerebral blood vessel. The 3T-TOF MRA was performed for 31 patients who were suspected of having cerebrovascular disease from March to July 2010. For evaluation of cerebral blood vessel, classification was conducted randomly: group I that included vertebral artery and basilar artery, group II that ranged from 2.5cm before basin part of common carotid artery to basin part of internal and external carotid arteries and to genu part of internal carotid artery, group III that ranged from vertebral part of internal carotid artery to the first basin art of anterior and middle cerebral through education recognizes the importance of dose reduction and examine if their efforts and further reduce patient dose could achieve optimization of the medical exposure is considered.

• Journal of Welding and Joining
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• 제27권4호
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• pp.49-53
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• 2009

For Al 6k21-T4 alloy, linear laser welding produced the lower shear-tensile strength than the base metal. This study improved the shear-tensile strength by using the weaving laser at the optimized welding condition, i.e., 2mm weaving width and 25Hz frequency. The large weaving width increased the weld width, therefore improving the joint strength. For the specimen of low strength, the porosity was distributed continuously along the intersection between the plates and fusion line. However, for the optimized welding condition, large oval-shaped porosities were located only in the advancing track of the concave part. Regardless of the welding condition, solidification cracking was initiated at the intersection and propagated through small porosities in the weld part. furthermore, the concave part had more significant porosity in the weld and HAZ, respectively than the convex part. The continuity of porosities played a key role to determine the strength. And, the weaving width was an important parameter to control the strength.

• 한국통신학회논문지
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• 제37C권12호
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• pp.1281-1288
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• 2012

본 논문은 재난 정보를 다양한 모바일방송 규격에 따라 인코딩 및 송출, 수신 및 디코딩하는 멀티모드 방송용 EWS 송 수신 시스템의 설계 및 구현 방법을 제안한다. 제안한 시스템은 전 세계 모바일 방송 표준 중 T-DMB, DVB-H, ISDB-T와 디지털 라디오 규격인 DRM을 지원하며, 각각의 방송 규격에 따라 재난 정보를 인코딩하는 송출부와 각 표준에 따른 RF 방송 신호를 수신 및 디코딩하는 수신부 형태로 구성된다. 제안한 멀티모드 방송용 EWS 송신시스템은 단일 시스템상에서 각각의 방송규격으로 EWS 재난 데이터 생성하고 상용 방송 송출 장비규격에 만족하는 채널 인터페이스를 통해 재난정보가 송출 가능하며 수신 시스템에서는 단일 H/W에서 해당 모드의 재난 정보를 수신, 디코딩하여 단말기 화면에 표출한다. 제안된 시스템은 실시간으로 각 모드별 상용 방송장비에서 송출되는 RF 신호를 수신하여 문자기반의 재난 정보를 표출하는 정합 검증 과정을 통해 정상동작 결과를 제시한다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.173-178
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• 2005

In this paper, an efficient and robust analysis system for the flutter optimization of laminated composite wings has been developed using the coupled computational method based on the genetic algorithm. General three-dimensional doublet-lattice method is efficiently used to compute generalized aerodynamic forces of T-tail configuration in the frequency domain. Structural dynamic analyses of laminated composite T-tail models are conducted using finite clement method. The classical P-k flutter analysis technique is applied to effectively solve the aeroelastic governing equations in the frequency domain. Optimum design studies using genetic algorithm have been conducted in order to obtain maximum flutter stability of a composite T-tail configuration. The results show that flutter stability can be significantly increased using composite materials with proper optimum design concepts even for the same weight and shape condition. In the view point of engineering design, it is also importantly shown that the optimization of the vertical wing part is highly effective comparing to the optimization of horizontal wing part.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1923-1924
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• 1996

Some part of the route in KEPCO 765kV transmission line being constructed passes through a high mountain area which is 800m above the sea level (Taebaek, Sabuk area in Gangwon province). This area is the top part of Taebaek mountains corresponding to the backbone of korean peninsula and has lots of snow during the winter season because the winter seasonal wind gone up along the mountainside of Taebaek Mts. meets open air of the East sea. KEPCO has experienced 63 faults of T/L between 1968 and 1993 in this area, which is a very serious problem. Especially 154kV Hwang-Ji T/L fault in 1990, 2 was a unprecedented case which needs to be analyzed carefully to take proper measures. After reviewing ice and snow loading conditions and analyzing the fault of Hwang-Ji T/L, we're going to determine the revisement of ice and snow loading condition in this area to increase reliability of 765kV transmission line.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.246-253
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• 2000

The optimal equations to predict the soil tempratures of twelve cities in the region of the southern part of the Korea such as Changhung, Cheju, Chinju, Kwangju, Masan, Miryang, Mokpo, Muan, Pusan, Sogwipo, Ulsan, Yoosu, were suggested as function of time and soil depth and the time dependent variation and soil depth dependent distribution of temperature were analyzed for the back data of the geothermal energy utilization system design and agricultural usages. The equation form is $T(x,\;t)\;=\;T_{m}\;-\;T_{so}{\cdot}Exp(-\xi){\cdot}cos{\omega}(t\;-\;t_{o}\;-\;x\;/\sqrt{2{\alpha}{\omega}}$) and it can predict the soil temperatures well with the correlation factor of 0.98 or upwards for most data. The range of mean soil temperature was $14.99~18.53^{\circ}C$ and soil surface temperature swing, 11.65~14.54 days, soil thermal diffusivity, $0.025~0.069\;m^2/day$ except Mokpo of $0.100\;m^2/day$, and phase shift, 19.66~27.81 days. During about thirty years from 1960s to 1990s, the mean soil temperature was increased by $0.04~1.25^{\circ}C$. The temperature difference depending on soil depth was not significant.

• 상하수도학회지
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• 제22권1호
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• pp.113-120
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• 2008

A large majority of clearwell must be modified with maintaining the present baffles since they were underground built with the material like concrete. Therefore it is unreasonable to apply the previous research in clearwell modification which is studied with the assumption that distance between baffles is constant. In this study, internal short-circuiting estimation method (ISEM), which has the advantage of being applied at any condition, is applied to evaluate modification of A clearwell and modify B and C clerwell which have unusual characteristics. After analyzing the hydraulic efficiency at current state, modifications, where baffles, intra basins and diffuser walls are additionally installed, are considered and evaluate using ISEM. And the effect of intra basin and diffuser wall on $T_{10}/T$ is estimated and application feasibility of ISEM is evaluated. The improvement of intra basins is almost same with that of baffles. Also, short-circuiting in effluent zone can be reduced with the same level of channel zone if intra basin is added in effluent zone. However, effect range is restricted to the next channel zone. Diffuser wall can obtain the lower ISI than minimum ISI of cases where baffles and intra basins are installed. Therefore, additional improvement of $T_{10}/T$ value can be expected after $T_{10}/T$ value converges maximum only using baffles

• 대한수의학회지
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• 제42권2호
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• pp.131-136
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• 2002

The vertebrae of female African elephant (Loxodonta africana) of twenty-eight years old were observed macroscopically. The result was summarized as follows; the vertebral formula of African elephant was $C_7$ $T_{21}$ $L_3$ $S_4$ $Cd_{21}$. The total length of the vertebral column removed intervertebreal disks was 353 cm. The length of each segment of vertebral column was 44 cm in cervical, 142 cm in thoracic, 21 cm in lumbar, 27 cm in sacral and 119 cm in caudal vertebrae. The 17th and 18th thoracic vertebrae (T) were partially fused each other in four parts: the transverse processes of 17th and 18th T, caudal articular process of 17th T and cranial articular process of 18th T, left mammilary process of 18th T and left transverse process of 17th T, and vertebral arch of 17th and 18th T, respectively. Others partial fusions also observed among the third luwbar, sacrum and ilium. These were in between transverse process of third lumbar vertebra and cranial parts of wing of sacrum, lateral part of sacrum and tuber sacrale, respectively. The sternum was consisted of three pieces; one is a part of anterior prestemum, two is the part from caudal demifacet at second facet to cranial demifacet at third facet in middle mesosternum, which is divided vertically into an half at second and third facets, respectively, and the last is the part between caudal demifacet of third facet in middle mesosternum and the posterior xiphisternum. There are 21 pairs of ribs, six sternal, ten asternal ribs and the last five being floating ribs.

• 한국음향학회지
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• 제41권1호
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• pp.87-98
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• 2022

음악은 일상생활의 어려움과 스트레스를 축소함으로 노인의 삶의 질에 긍정적인 영향을 미친다. 본 연구는 한국 노인들을 대상으로 음악지각과 참여와 관련된 한국어판 삶의 질 설문지를 개발하고자 한다. 한국어판 음악관련 삶의 질 설문지(Korean version of Music-Related Quality of Life, K-MRQoL)은 음악능력, 태도, 활동빈도(Part 1)과 음악능력, 태도, 활동중요성(Part 2)으로 구성되었고 각 하위범주는 11문항으로 구성된 음악지각과 7항목으로 구성된 음악참여로 구성되었다. 복지센터와 양로원의 난청 노인30명과 정상청력 노인 30명을 대상으로 피어슨, 크론바크 알파 상관계수와 독립 t 검사를 측정하었다. K-MRQoL의 전체점수와 하위범주(Part 1)간의 상관계수는 .701에서 .948이었고 하위범주(Part 2)간의 상관계수는 .598에서 .926이었다. K-MRQoL의 전체점수와 하위범주(Part 1) 간의 내적일관성은 .846에서 .931이었고 하위범주(Part 2) 간의 내적일관성은 .838에서 .918이었다. K-MRQoL의 전체 점수와 하위범주(Part 1과 2)의 검사-재검사의 상관계수는 각각 .979, .970, .979이었다. K-MRQoL과 의사소통 삶의 질척도(Quality of Communication Life Scale, QCL)와의 상관관계는 .449이었다. K-MRQoL 전체점수와 하위범주(Part 1과 2)는 건청과 난청 노인 간 통계적으로 의미있는 차이를 보였다. 따라서 한국어판 음악관련 삶의 질 설문지는 건청과 난청노인의 음악관련 삶의 질을 심층적으로 살펴볼 수 있는 유용한 임상적 도구임을 나타낸다.