• Earthquakes and Structures
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• 제26권5호
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• pp.401-416
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• 2024

Long-span structures, such as bridges, can experience different seismic excitations at the supports due to spatially variability of ground motion. Regarding current bridge designing codes, it is just EC 2008 that suggested some regulations to consider it and in the other codes almost ignored while based on some previous studies it is found that the effect of mentioned issue could not be neglected. The current study aimed to perform a comprehensive study about the effect of spatially varying ground motions on the dynamic response of a reinforced concrete bridge under asynchronous input motions considering soil-structure interactions. The correlated ground motions were generated by an introduced method that contains all spatially varying components, and imposed on the supports of the finite element model under different load scenarios. Then the obtained results from uniform and non-uniform excitations were compared to each other. In addition, the effect of soil-structure interactions involved and the corresponding results compared to the previous results. Also, to better understand the seismic response of the bridge, the responses caused by pseudo-static components decompose from the total response. Finally, an incremental dynamic analysis was performed to survey the non-linear behavior of the bridge under assumed load scenarios. The outcomes revealed that the local site condition plays an important role and strongly amplifies the responses. Furthermore, it was found that a combination of wave-passage and strong incoherency severely affected the responses of the structure. Moreover, it has been found that the pseudo-static component's contribution increase with increasing incoherent parameters. In addition, regarding the soil condition was considered for the studied bridge, it was found that a combination of spatially varying ground motions and soil-structure interactions effects could make a very destructive scenarios like, pounding and unseating.

• 한국지진공학회논문집
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• 제28권3호
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• pp.149-158
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• 2024

Piloti-type structures with vertical irregularity are vulnerable to earthquakes due to the soft structure of the first story. Structural characteristics of buildings can significantly affect the seismic loss function, calculated based on seismic fragility, and therefore need to be considered. This study investigated the effects of the number of stories and core locations on the seismic loss function of piloti-type buildings in Korea. Twelve analytical models were developed considering two variations: three stories (4-story, 5-story, and 6-story) and four core locations (center core, x-eccentric core, y-eccentric core, and xy-eccentric core). The interstory drift ratio and peak floor acceleration were assessed through incremental dynamic analysis using 44 earthquake records, and seismic fragility was derived. Seismic loss functions were calculated and compared using the derived seismic fragility and repair cost ratio of each component. The results indicate that the seismic loss function increases with more stories and when the core is eccentrically located in the piloti-type structure model. Therefore, the uncertainty due to the number of stories and core location should be considered when deriving the seismic loss function of piloti-type structures.

• 아태비즈니스연구
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• 제14권4호
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• pp.191-204
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• 2023

Purpose - The purpose of this study was to analyse the relationship between R&D tax support policy and firm innovation activity using data on firms engaged in 12 national strategic technology sectors. Design/methodology/approach - This study collected survey data from 664 companies engaged in national strategic technologies. The data were then analysed using the Propensity Score Matching (PSM) analysis. Findings - First, corporate R&D tax support had a statistically significant positive (+) relationship with firm innovation performance. Second, there was a statistically significant positive (+) relationship with incremental innovation, but there was no statistical significance with radical innovation. Third, there was a statistically significant positive (+) relationship with the firm's first innovation, but there was no statistical significance with the world's first innovation. Fourth, there was a statistically significant positive (+) relationship with the number of R&D projects of a firm. Finally, there was a statistically significant positive (+) relationship with a firm's open innovation. Research implications or Originality - First, in terms of policy effectiveness, the government needs to consider promoting R&D tax support policies in areas where R&D competition is fierce. For private companies engaged in the 12 national strategic technology fields, the R&D tax support policy is working in the direction of promoting corporate innovation activities, and this positive policy effect is likely to be effective in areas where R&D competition is fierce. Second, if the government wants to improve the quality of corporate innovation activities through R&D tax support policies, it needs to provide incentives higher than the current level.

• 한국구조물진단유지관리공학회 논문집
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• 제11권6호
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• pp.113-120
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• 2007

연약지반에 시공되는 보강토옹벽과 개비온옹벽에 대해서 옹벽의 안정성을 확보하기 위해 필요한 적정 치환영역을 유한요소해석을 통해 검토하였다. 해석은 연약토층의 압밀단계를 포함하여 시공순서를 모사하는 단계별 해석방법으로 수행되었다. 적정 치환영역의 제안을 위한 첫 단계로 치환깊이를 변화시킨 경우들에 대해서 시공단계에 따른 벽체 및 주변 지반의 거동을 조사하는 일련의 해석을 수행하였다. 이들 해석결과를 문헌연구를 통하여 설정한 옹벽의 안정성을 보장할 수 있는 벽체변위, 지반의 침하량 및 전단변형율 등의 한계값과 비교, 평가하였다. 그 결과, 본 연구에서 검토한 지반조건에서 벽체의 높이가 변하는 경우에 대한 적정 치환영역을 벽체의 높이에 대한 치환깊이의 비로 나타내는 시공표준도를 제안하였다

• 대한핵의학회지
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• 제24권2호
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• pp.244-253
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• 1990

Sixty-four patients with paradoxical ventricular wall motion noticed both in angiocardiography or 2-dimensional echocardiography were assessed by ECG gated blood pool scan (GBPS). Endless cine loop image, phase and amplitude images and paradox image obtained by visual inspection of each cardiac beat or Fourier transformation of acquired raw data were investigated to determine the incremental value of GBPS with these processing methods for identification of paradoxical ventricular wall motion. The results were as follows: 1) Paradoxical wall motions were observed on interventricular septum in 34 cases, left ventricular free wall in 26 and right ventricular wall in 24. Underlying heart diseases were ischemic (23 cases) valvular(9), congenital heart disease (12), cardiomyopathy (5). pericardial effusion(5), post cardiac surgery(3), col pulmonale (2), endocarditis(1) and right ventricular tumor(1). 2) Left ventricular ejection fractions of patients with paradoxical left ventricular wall motion were significantly lower than those with paradoxical septal motion(p<0.005). 3) The sensitivity of each processing methods for detecting paradoxical wall motion was 76.9% by phase analysis, 74.6% by endless cine loop mapping and 68.4% by paradox image manipultion respectively. Paradoxial motions visualized only in phase, paradox or both images were appeared as hypokinesia or akinesia in cine loop image. 4) All events could be identified by at least one of above three processing methods, however only 34 cases (48.4%) showed the paradoxical molies in all of the three images. By these findings, we concluded that simultaneous inspection of all above three processing methods-endless cine loop, phase analysis and paradox image-is necessary for accurate identification and assessment of paradoxical ventricular wall motion when performing GBPS.

• 콘크리트학회논문집
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• 제14권3호
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• pp.382-391
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• 2002

본 연구에서 초기재령 콘크리트의 크리프 특성을 고려한 단면 내 온도 및 수축응력을 구하는 3차원 유한요소 해석 프로그램을 개발하기 위한 수치해석 절차에 관하여 정립하였다. 최근 들어 구조물의 노후화에 따른 콘크리트의 내구성에 대한 관심이 고조되고 있고, 초기재령에서 발생하는 균열은 구조물의 내구성 및 사용성과 같은 장기적인 성능에 큰 영향을 미친다. 많은 토목 기술자들이 초기재령 콘크리트의 체적변화에 의한 응력 및 균열 문제를 심도 깊게 다루지 않는 데는 장기적인 내구성과 사용성에 대한 인식이 부족하고, 경화가 진행되는 콘크리트의 체적변화는 매우 복잡한 영향인자를 고려해야 되기 때문이다. 또한 초기재령 콘크리트의 체적변화로 인한 응력을 예측하는 기존 프로그램들은 주로 수화열에 의한 온도 및 열응력 해석에 국한되거나, 수화과정과 연계되지 않은 습도분포에 의한 수축 응력해석을 대상으로 한다. 따라서 본 연구에서는 초기재령 콘크리트의 체적 변화에 의한 모든 응력 요소를 하나의 통합적인 해석 시스템으로 구성하여, 초기재령 콘크리트의 균열 제어 수단으로 활용하고자 한다. 본 연구는 초기재령 콘크리트의 온도 및 수분에 관련된 재료 물성 뿐 만 아니라 역학적 특성 등 모든 재료 물성을 수화도에 기초하여 모델링하였다. 또한 콘크리트가 강성을 가지는 시점부터의 초기재령 크리프 실험을 수행하고, 그 결과로부터 수화도에 따른 크리프 거동을 모델링하여 해석 프로그램에 반영하였다. 개발된 해석프로그램을 이용하여 수치해석 결과와 실험결과를 비교하여 그 타당성을 검증하고, 해석 예제를 통하여 각 변형률 성분에 의한 잔류 응력의 변화 양상을 비교, 분석하였다.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제5권3호
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• pp.155-164
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• 2016

대용량 데이터베이스의 빈도패턴 분석을 위해 기존의 Apriori 방식의 단점을 보완할 수 있는 새로운 트리 기반의 빈도 패턴 분석 알고리즘이 최근 다양하게 연구되고 있다. 그 중 FP-tree는 이러한 빈도 패턴을 분석하기 위해 빈도 패턴을 표현하는 트리 구조로 단 두 번의 전체 데이터베이스 스캔을 통해 빠르게 트리를 구성할 수 있으며 FP-grwoth를 통해 빈도 패턴을 분석할 수 있다. 이처럼 빈도 패턴 트리의 노드 수는 트리 자체의 메모리 할당량과도 연관이 있지만 그 후 growth의 메모리 자원 소비 및 처리 속도에도 영향을 미치게 된다. 따라서 빈도 패턴 트리의 노드 수의 감소는 트리 자체뿐만 아니라 빈도 패턴 분석에 있어서도 매우 중요하다. 하지만 FP-tree는 전체 아이템 수 라는 고정된 기준 문제로 인해 충분한 노드 수의 압축률을 갖지 못하고 있다. 본 논문에서는 이러한 FP-tree의 문제를 보완하여 좀 더 노드 수를 감소시킬 수 있도록 교집합 규칙이라는 새로운 패러다임을 적용한 빈도 패턴 트리인 IRFP-tree를 제시하고 실험을 통해 그 성능에 대해 증명하였다.

• 한국산학기술학회논문지
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• 제20권2호
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• pp.605-621
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• 2019

본 연구는 사회경제적 계층에 대한 고정관념과 편견을 측정하는 한국판 대학생용 계층차별주의 태도 척도를 개발하고 타당화하는데 그 목적이 있다. 이를 위해 연구 1에서는 관련 문헌, 대학생들 대상으로 한 개방형 설문지 자료를 수정된 합의적 질적 연구 방법으로 분석한 결과 및 전문가 자문을 토대로 주요 구인과 초기예비문항을 제작한 후 440명의 대학생을 대상으로 탐색적 요인분석과 신뢰도 분석을 실시하였다. 다음으로 연구 2에서는 400명의 대학생을 대상으로 총 14문항에 대해 확인적 요인분석을 실시하였고, 그 결과 연구 1에서 도출된 상향 계층차별주의 태도와 하향 계층차별주의 태도의 2개 요인이 자료에 적합한 것으로 나타났다. 신뢰도 및 타당도 검증 결과, 높은 수준의 검사-재검사 신뢰도와 더불어, 연령, 주관적 계층, 정당한 세상에 대한 일반적인 믿음, 부정 정서(우울, 불안), 적대감과의 유의미한 상관관계를 통해 준거타당도가 확인되었다. 또한, 연령, 주관적 계층, 가정의 총수입, 및 정당한 세상에 대한 일반적 믿음 외에 K-CAS가 추가적으로 부정정서(우울, 불안) 변량의 5%를 설명하여 증분타당도도 확인되었다. 본 연구는 향후 국내에서 계층차별주의 관련 개입 및 예방 연구 및 프로그램 개발 등에 활용 할 수 있는 도구를 개발하고 타당화하였다는 점에서 주요 시사점이 있다.

• 대한간호학회지
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• 제26권4호
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• pp.768-781
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• 1996

The problem of care of patients and families with Alzheimer's disease has become a conscious raising social policy issue in Korea. The government of the Republic of Korea has become cognizant of the situation and has begun searching for ways to remedy it. Thus, there is a need for a comprehensive under-standing of the situation in which patients and their families are struggling and the enormous problems of care. With a realization of the urgent need, this study was done to investigate the situation and the care needs of families with patients with Alzheimer's Disease, and to compare the effectiveness of services utilized by the families in terms of cost and effects on patient's conditions and on family live. The Subjects for the study were 29 families with hospitalized patients, 25 families utilizing hospital outpatient clinics, 14 families utilizing day care facilities, and 16 families with homebound patients. A total of 84 families were interviewed by four trained interviewers using structured and semistructured questionnaires. The data produced from these interviews included : the patient's stage of Alzheimer's disease, patient's bizarre behavior, hours spent on patient care per day, family burden and quality of life, direct and indirect costs encountered in the care of patients, and the families' evaluation of the effectiveness of the services received. The data were analyzed to determine the relationships between family charactersistics, patient's conditions and services utilization. The effectiveness of each of the service entities was assessed through families evaluation and hoped for service and comparisons were made between services in terms of the cost-effectiveness ratios. After initial comparison of cost-effectiveness ratios, further analysis was done to compare between groups for incremental effectiveness for each incremental unit of cost to determine the most cost-effective service entities. The findings of the study are as fellows : 1. The choice of living arrangement and the types of services are a function of the stage of Alzheimer's condition and the economic status of the family. 2. Comparision of the cost of care showed that most expenses were encountered in by families with hospitalization, families using outpatient services, and families using day care services in that order. The least expense was involved in the care of homebound patients. The economic burden felt by families was in the same order as expenses. 3. The average number of hours spent on daily patient care was 9.9 hours for the outpatient clinic users, 9.7 hours for homebound patients, and 5.4 hours for day care users. 4. There were significant differences in the patient's conditions (CDRL), bizarre behaviors and the families's burden by living arrangement and /or types of service. However, no significant difference was found between groups in the family's quality of life. 5. The families rated the services of day care center as most effective for the care of the patients and families, except for a few families who had experienced some improvement in the patient's conditions. The outpatient clinic users expressed psychological comforts mainly in that the patient was being taken care of. For those hospitalized patients, families expressed the comfort of being relieved of the burden of care and that the patient is being professionally cared for. Form the analysis of the costs, hours of patient care, patient's bizarre behaviors, family's quality of life and burdens, and family's evaluation of services, it is concluded that up to the mid stage of Alzheimer's condition, the utilization of day care center services is found to be the most cost-effective, and toward the end stage of the Alzheimer's disease, it is hoped that there will be a establishment of long term or short term in-patient facilities for the protection of patients and preservation of the integrity of families for less cost. Thus. it was concluded that the family centered system of care is the most effective for Korea with systematic support systems developed for the care of patients and their families according to the needs of families as the patient's condition deteriorates.

• Fisheries and Aquatic Sciences
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• 제22권12호
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• pp.31.1-31.12
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• 2019

Background: The black-chinned tilapia, Sarotherodon melanotheron, is the most abundant fish species in the Nakwa (an open lagoon) and Brenu (a closed lagoon) in the Central Region of Ghana. Aspects of the life history characteristics and the ecology of the fish populations in both lagoons were studied to assess the bio-ecological status of this important resource. Methods: Fish samples were obtained from fishermen that fish on the Nakwa and Brenu lagoons using cast, drag and gill nets. The age of the fish was assessed from otoliths analysis and its growth modelled following the von Bertalanffy growth function. Morphometric characteristics of the fish populations were analysed using power regression and ANOVA for parameters comparisons, and Student's t test to determine whether species grew isometrically. The percentage occurrence method was used to analyse the stomach contents of the fish. Results: A total of 382 fish samples from both lagoons were measured, comprising 209 from Nakwa lagoon and 176 from Brenu lagoon. The size and weight of fish samples ranged between 3.9-11.5 cm total length and 1.0-27.3 g for Nakwa Lagoon and 5.6-12.8 cm total length and 3.2-29.8 g for the Brenu Lagoon. The estimated von Bertalanffy growth parameters were L∞ = 12.04 cm and K = 2.76/year for the Nakwa Lagoon samples and L∞ = 13.44 cm and K = 3.27/year for Brenu Lagoon samples. Daily otolith incremental rate ranged from 0.01-0.03 mm per day to 0.01-0.02 mm per day for Nakwa and Brenu lagoons, respectively. Stomach content analysis of the fish samples revealed that the species are planktivorous and the range of food varied between the lagoons. Green algae were the most prevalent food item in the stomachs of the fish samples from Nakwa with the frequency of 69% whilst diatoms (80.5%) were most prevalent phytoplanktonic food item for the fish in Brenu lagoon. Conclusions: The estimates of asymptotic length for the species in both lagoons are close to known values of the species length at first sexual maturity and points to intensive fishing pressure. As a consequence, a comprehensive sample-based survey is required in both lagoons to derive estimates of management reference points. The results of the stomach content analysis are beneficial to the construction of diet matrix for ecosystem models of the two systems.