• 대한예방한의학회지
• /
• 제14권3호
• /
• pp.63-75
• /
• 2010

Vascular dementia(VaD) is currently considered to be the second most common type of dementia. VaD is not a single diagnostic entity, but a heterogeneous syndrome which encompasses several clinicopathological forms of dementia resulting from cerebrovascular diseases. A common form of VaD is subcortical VaD which is characterized by lacunar infarcts and deep white matter changes, leading to a progressive decline in memory and cognitive function. The neuropsychological and cognitive profiles of subcortical VaD have been reported relatively homogeneous. At present, subcortical vascular dementia is regarded as the most important subtype of VaD with getting the attention of vascular dementia. The aims of this study are to discuss the concept of subcortical VaD and its importance focusing on diagnosis, prevention and treatment with a case report.

• 농촌계획
• /
• 제11권1호
• /
• pp.1-8
• /
• 2005

The purpose of this study is to develop a simulation model of rural road path for infrastructure of green-tourism and public service in rural areas. This study makes an objective function for moving cost minimization considering car travel time according to road characteristics, which can route the optimal shortest road paths between the center places and all rear villages, based on GIS coverages of road-village network for connecting between center places and rural villages as input data of the model. In order to verify the model algorithm, a homogeneous hexagonal network, assuming distribution of villages with same population density and equal distance between neighborhood villages on a level plane area, was tested to simulate the optimal paths between the selected center nodes and the other rear nodes, so that the test showed reasonable shortest paths and road intensity defined in this study. The model was also applied to the actual rural area, Ucheon-myun, which is located on Hoengsung-gun, Kangwon-do, with 72 rural villages, a center village (Uhang, 1st center place) in the area, a county conte. (Hoengsung-eup, 2nd center place), and a city (Wonju, 3rd center place), as upper settlement system. The three kinds of conte. place, Uhang, Hoengsung-eup, and Wonju, were considered as center places of three scenarios to simulate the optimal shortest paths between the centers and rural villages, respectively. The simulation results on the road-village network with road information about pavement and width of road show that several spans having high intensity of road are more important that the others, while some road spans have low intensity of road.

• Archives of Reconstructive Microsurgery
• /
• 제14권2호
• /
• pp.105-111
• /
• 2005

Perforator flaps have become increasingly popular in microsurgery nowadays and are being used widely for many cases of reconstruction after trauma and cancer ablation. And thoracodorsal perforator based free flap is one of them having the merits of carrying a large skin paddle with leaving intact innervation and function of the remaining latissimus dorsi muscle. We made a homogeneous thin flap excluding the main muscle with a long vascular pedicle and tried to decrease the donor site morbidity. But, it needs a long learning-curve and we have met marginal flap necrosis frequently. Besides, prolonged operation time for complete perforator dissection may be a tedious job to the microsurgeon. To overcome these disadvantages, we usually included very small portion of the latissimus dorsi muscle during this flap elevation around the pedicled 2-3 thoracodorsal perforators during this flap elevation. We performed 3 cases of thoracodorsal perforator based free flap at Hallym university sacred heart hospital between May and August 2005 for the soft tissue defect of the scalp and feet. The average flap size was $8{\times}14\;cm$. Although it is not a true perforator flap, we can get the reliability for the flap survival with much better blood circulation and save the time of one or two hours to dissect the perforators completely. All cutaneous flaps survived completely without any complication except one fatty female who had the very small superficial fat necrosis due to flap bulkiness. We believe the thoracodorsal perforator based free flap can be extended its versatility and reliability by including the very small portion of the muscle around the perforators.

• 한국정보통신학회논문지
• /
• 제11권12호
• /
• pp.2311-2318
• /
• 2007

유한고장수를 가진 비동질적인 포아송 과정에 기초한 모형들에서 잔존 오류 1개당 고장 발생률은 일반적으로 상수, 혹은 단조증가 및 단조 감소 추세를 가지고 있다. 소프트웨어 제품의 정확한 인도시기를 예측하거나 효용성 및 신뢰성을 예측하기 위해서는 소프트웨어 테스팅 과정에서 중요한 요소인 테스트 커버리지를 이용하면 보다 효율적인 테스팅 작업을 할 수 있다. 이런 모형을 ENHPP모형이라고 한다. 본 논문에서는 기존의 소프트웨어 신뢰성 모형인 지수 커버리지 모형과 S-커버리지 모형을 재조명하고 이 분야에 적용될 수 있는 Kappa 분포를 이용한 모형인 Kappa 커버리지 모형을 제안하였다. 고장 간격시간으로 구성된 자료를 이용한 모수추정 방법은 최우추정법과 일반적인 수치해석 방법인 이분법을 사용하여 모수 추정을 실시하고 효율적인 모형 선택은 편차자승합(SSE) 및 콜모고로프 거리를 적용하여 모형들에 대한 효율적인 모형 선택도 시도 하였다. 수치적인 예에서는 실제 고장자료를 통하여 분석하였다 이 자료들에서 기존의 모형과 Kappa 커버리지 모형의 비교를 위하여 산술적 및 라플라스 검정, 편의 검정 등을 이용하였다.

• 한국분말재료학회지
• /
• 제26권5호
• /
• pp.410-414
• /
• 2019

The hydrogen reduction behavior of the $CuO-SCo_3O_4$ powder mixture for the synthesis of the homogeneous Cu-15at%Co composite powder has been investigated. The composite powder is prepared by ball milling the oxide powders, followed by a hydrogen reduction process. The reduction behavior of the ball-milled powder mixture is analyzed by X-ray diffraction (XRD) and temperature-programmed reduction at different heating rates in an Ar-10%H2 atmosphere. The scanning electron microscopy and XRD results reveal that the hydrogen-reduced powder mixture is composed of fine agglomerates of nanosized Cu and Co particles. The hydrogen reduction kinetics is studied by determining the degree of peak shift as a function of the heating rate. The activation energies for the reduction of the oxide powders estimated from the slopes of the Kissinger plots are 58.1 kJ/mol and 65.8 kJ/mol, depending on the reduction reaction: CuO to Cu and $SCo_3O_4$ to Co, respectively. The measured temperature and activation energy for the reduction of $SCo_3O_4$ are explained on the basis of the effect of pre-reduced Cu particles.

• 한국시뮬레이션학회:학술대회논문집
• /
• 한국시뮬레이션학회 1992년도 제2회 정기총회 및 추계학술 발표회 발표논문 초록
• /
• pp.9-9
• /
• 1992

시뮬레이션(simulation)은 실 시스템(real system)의 효과적이고 효율적인 운영을 도모하기 위하여 실 시스템의 동작을 이해하고 분석, 예측, 평가하는 과학적인 문제해결 접근방법이다. 시뮬레이션 수행단계는 실 시스템의 행위를 정확히 반영하도록 타당한 모델을 구축하는 모델링 단계와 모델에 의도하는 명령어들을 컴퓨터 프로그램으로 작성하는 구현단계로 나누어진다. 시뮬레이션 모델은 시간, 상태, 확률변수, 상호규칙 등의 여러 관점에 따라 다양하게 존재하는데, DEVS(Descrete EVent system Specification) 모델은 연속적인 시간상에서 이산적으로 발생하는 사건에 따라 시스템의 상태를 분석할 수 있고 모델링 및 시뮬레이션 방법론의 형식화를 위한 견고한 이론적 기반을 제공하고 있다. 또한, DEVS 모델은 모듈적, 계층적 특성을 제공하고 집합론에 근거한 수학적 형식구조를 제공하여 실 시스템에 대한 체계적인 분석과정을 수행하게 되어 보다 현실적인 모델링을 가능하게 한다. 그러나 타당하지 못한 DEVS 모델이 구축되면 시뮬레이션을 통한 분석결과의 신뢰성이 떨어져 아무런 효과가 없고 경제적인 손실만이 따른다. DEVS 모델에 대한 기존의 타당성 검사가 많은 시간과 노력이 요구되고, 반복적인 DEVS 모델링 과정으로 인한 전문적이고 경험적인 지식을 요구한다. 또한, 모델설계자에 의해 설정된 실험 프레임하에서 DEVS 모델의 구성요소에 속하는 상태전이함수, 시간진행함수 및 출력함수에 대하여 commutative 성질의 보전성 검사가 어렵다는 문제점을 가지고 있다. 본 연구에서는 이와 같은 문제점을 해결하기 위하여, DEVS 모델에 대한 타당성 검사를 SPN(Stochastic Petri Net) 모델로 변환하여 SPN 모델을 이용하는 간단하고 효과적인 타당성 검사 방법을 제안한다. 먼저, DEVs 모델에 대한 개념과 기존의 DEVS 모델에 대한 타당성 검사 방법을 고찰하고 그 문제점에 대하여 자세히 설명한다. DEVS 모델의 타당성 검사에 이용하는 SPN 모델에 대한 개념과 DEVS 모델과 행위적으로 동등한 SNP 모델로 변환을 위한 관점을 제조명하다. 동일한 관점에서 두 모델의 상태표현이 같도록 DEVS 모델이 SPN 모델로 표현됨을 보이는 변환이론을 제시하고 변환이론을 바탕으로 모델 변환과정을 제시한다. 모델 변환이론과 변환고정을 기본으로 타당성 검사를 위한 새로운 동질함수(homogeneous function)를 정의하고 이와 함께 SPN 모델의 특성을 이용하여 DEVS 모델에 대한 타당성 검사 방법을 새롭게 제안한다.

• 한국환경과학회지
• /
• 제28권9호
• /
• pp.785-795
• /
• 2019

In order to analyze the sensitivity of carbon dioxide flux by soil temperature in the grassplot, carbon dioxide flux and soil temperature were observed 24 times from March, 2010 to March, 2011 at nine sites in the grassplot. The average of $CO_2$ in the grassplot is $2.2{\sim}36.7^{\circ}C$, the highest in August, the lowest in January, and the average of carbon dioxide flux is $12{\sim}1479mgCO_2{\cdot}m^{-2}{\cdot}hr^{-1}$, and the carbon dioxide emission from the grassplot to the atmosphere was 10 times higher in summer than in winter. The temperature response coefficient estimated by the exponential function of carbon dioxide flux according to soil temperature was ranged from 0.1065 to 0.1274, and the increase tendency of $CO_2$ flux with soil temperature was linear at $0{\sim}20^{\circ}C$ and exponential at $20{\sim}40^{\circ}C$. The $Q_{10}$ values for each of nine observation sites on the grassplot was in the range of 2.901 ~ 3.575, and the $Q_{10}$ value using the total data observed in the lawn was estimated to be 3.374. In the homogeneous grassplot area, the average of $Q_{10}$ values by observation point and the $Q_{10}$ value by the total data were estimated similarly.

• 한국발생생물학회지:발생과생식
• /
• 제25권3호
• /
• pp.133-143
• /
• 2021

In contrast to the human lutropin receptor (hLHR) and rat LHR (rLHR), very few naturally occurring mutants in other mammalian species have been identified. The present study aimed to delineate the mechanism of signal transduction by three constitutively activating mutants (designated M410T, L469R, and D590Y) and two inactivating mutants (D383N and Y546F) of the eel LHR, known to be naturally occurring in human LHR transmembrane domains. The mutants were constructed and measured cyclic adenosine monophosphate (cAMP) accumulation via homogeneous time-resolved fluorescence assays in Chinese hamster ovary (CHO)-K1 cells. The activating mutant cells expressing eel LHR-M410T, L469R, and D590Y exhibited a 4.0-, 19.1-, and 7.8-fold increase in basal cAMP response without agonist treatment, respectively. However, inactivating mutant cells expressing D417N and Y558F did not completely impaired signal transduction. Specifically, signal transduction in the cells expressing activating mutant L469R was not occurred with a further ligand stimulation, showing that the maximal response exhibited approximately 53% of those of wild type receptor. Our results suggested that the constitutively activating mutants of the eel LHR consistently occurred without agonist treatment. These results provide important information of LHR function in fish and regulation with regard to mutations of highly conserved amino acids in glycoprotein hormone receptors.

• Structural Engineering and Mechanics
• /
• 제85권5호
• /
• pp.593-605
• /
• 2023

This work presents a comparison between analytical and finite element analysis for bending of porous sandwich functionally graded material (FGM) plates. The plate is rectangular and simply supported under static sinusoidal loading. Material properties of FGM are assumed to vary continuously across the face sheets thickness according to a power-law function in terms of the volume fractions of the constituents while the core is homogeneous. Four types of porosity are considered. A refined higher-order shear with normal deformation theory is used. The number of unknowns in this theory is five, as against six or more in other shear and normal deformation theories. This theory assumes the nonlinear variation of transverse shear stresses and satisfies its nullity in the top and bottom surfaces of the plate without the use of a shear correction factor. The governing equations of equilibrium are derived from the virtual work principle. The Navier approach is used to solve equilibrium equations. The constitutive law of the porous FGM sandwich plate is implemented for a 3D finite element through a subroutine in FORTRAN (UMAT) in Abaqus software. Results show good agreement between the finite element model and the analytical method for some results, but the analytical method keeps giving symmetric results even with the thickness stretching effect and load applied to the top surface of the sandwich.

• 천문학회보
• /
• 제46권2호
• /
• pp.40.3-41
• /
• 2021

Minor mergers leave behind long lived, but extremely faint and extended tidal features including tails, streams, loops and plumes. These act as a fossil record for the host galaxy's past interactions, allowing us to infer recent accretion histories and place constraints on the properties and nature of a galaxy's dark matter halo. However, shallow imaging or small homogeneous samples of past surveys have resulted in weak observational constraints on the role of galaxy mergers and interactions in galaxy assembly. The Rubin Observatory, which is optimised to deliver fast, wide field-of-view imaging, will enable deep and unbiased observations over the 18,000 square degrees of the Legacy Survey of Space and Time (LSST), resulting in samples of potentially of millions of objects undergoing tidal interactions. Using realistic mock images produced with state-of-the-art cosmological simulations we perform a comprehensive theoretical investigation of the extended diffuse light around galaxies and galaxy groups down to low stellar mass densities. We consider the nature, frequency and visibility of tidal features and debris across a range of environments and stellar masses as well as their reliability as an indicator of galaxy accretion histories. We consider how observational biases such as projection effects, the point-spread-function and survey depth may effect the proper characterisation and measurement of tidal features, finding that LSST will be capable of recovering much of the flux found in the outskirts of L* galaxies at redshifts beyond local volume. In our simulated sample, tidal features are ubiquitous In L* galaxies and remain common even at significantly lower masses (M*>10^10 Msun). The fraction of stellar mass found in tidal features increases towards higher masses, rising to 5-10% for the most massive objects in our sample (M*~10^11.5 Msun). Such objects frequently exhibit many distinct tidal features often with complex morphologies, becoming increasingly numerous with increased depth. The interpretation and characterisation of such features can vary significantly with orientation and imaging depth. Our findings demonstrate the importance of accounting for the biases that arise from projection effects and surface-brightness limits and suggest that, even after the LSST is complete, much of the discovery space in low surface-brightness Universe will remain to be explored.