• Journal of Chest Surgery
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• 제52권2호
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• pp.91-99
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• 2019

Background: The relationship between the size of bullae and pneumothorax recurrence is controversial. The aim of this study was to retrospectively evaluate the role of blebs or bullae in predicting ipsilateral recurrence in young patients experiencing their first episode of primary spontaneous pneumothorax (PSP) who underwent conservative treatment. Methods: A total of 299 cases of first-episode PSP were analyzed. The status of blebs or bullae was reviewed on high-resolution computed tomography (HRCT). The dystrophic severity score (DSS; range, 0 to 6 points) was calculated based on HRCT. Results: The 5-year recurrence rate was 38.2%. In univariate analysis, age (<20 years), body mass index (<$20kg/m^2$), a unilateral lesion, and intermediate risk (DSS 4 and 5) were associated with recurrence. Sex; smoking history; and the presence, number, and maximal size of blebs or bullae were not related to recurrence. In Cox regression, age and intermediate risk were independent risk factors for recurrence. High risk (DDS 6) was not an independent risk factor. Conclusion: The presence, number, and size of blebs or bullae did not affect ipsilateral recurrence. DSS failed to show a positive correlation between severity and recurrence. The decision to perform surgery in patients experiencing their first episode of PSP should not be determined by the severity of blebs and bullae.

• 대한방사선기술학회지:방사선기술과학
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• 제46권1호
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• pp.9-14
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• 2023

When measuring cerebrovascular with 3D rotational angiography, the accuracy was verified by comparing the actual size and measurement size, respectively. It is intended to help select therapeutic materials and instruments during cerebrovascular intervention by comparing the average error rates for measured values in the 3DRA and CTA methods by examining with protocols such as brain CTA, which are always performed in emergency situations. The mean error rate between the groups of measurers was ±3.655% for radiation technologist and ±3.331% for university students, and the mean error rate of the student group was within tolerance (±10%), and the independent sample T-test result t =0.879, p=0.394 (p>0.05) showed no statistically difference between the two. In addition, the average error rate measured by both groups by 3DRA was measured below ±5% within the tolerance error rate (±10%), and most of CTA was measured within the tolerance range (±10%), but showed an average error rate of up to 5.65%, and the independent sample T-test result was statistically more accurate than 3DRA. Both the 3DRA method and the brain CTA method for measuring cerebrovascular size could be accurately measured within tolerance, but it would be better to measure cerebrovascular blood vessels using a more accurate 3DRA method during cerebrovascular intervention.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.790-802
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• 2017

This paper proposes the modeling and control strategy to track the MPPs of hybrid PV and Wind power systems, using a new dual input boost converter. The dual input power conditioning system with an independent MPPT control scheme is introduced with minimum number of circuit elements in order to reduce the switching loss, size and cost of the system. Since the operating conditions for the PV and Wind power systems are very distinct from each other, an efficient and superior control system is required to track the MPPs of both renewable sources with the use of a simply-structured single-ended single-inductor converter. The design of Power-Conditioning System (PCS) and detail control strategy are presented in this paper. To provide independent tracking of MPPs, a variable duty-cycle control strategy is employed for the wind system and a variable frequency strategy is employed for the PV system. Finally, the proposed dual-input converter for hybrid power conditioning system is implemented and the hardware test results are presented. From the hardware experiment, it is concluded that the proposed system successfully tracks the MPPs of both of the renewable power systems independently.

• 콘크리트학회논문집
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• 제13권6호
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• pp.637-644
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• 2001

본 논문에서는 콘크리트 댐체의 균열 발생 및 진전해석을 포함하는 비선형 지진해석에서 유한요소망 의존성을 제거시키고 안정적인 해를 얻기 위하여 균열모형으로 사용되는 소성손상모형 및 손상역학모형을 duvaut-lions모형에 기초한 점소성모형으로 정규화하는 방법을 기술하였다. 제안된 방법으로 정규화된 소성손상모형과 그렇지 않은 소성손상모형를 이용하여 지진하중을 받는 콘크리트 댐체의 동적 손상해석을 수행하여 여러 형태의 유한요소망이 해석결과에 미치는 영향을 분석하였다. 해석결과로부터 정규화한 소성손상모형은 유한요소망의 크기 및 배열에 영향을 크게 받지 않고 객관적이며 안정적인 해를 계산하는 반면, 정규화되지 않은 균열모형은 요소망에 의존적인 불안정한 결과를 산출함을 관찰할 수 있었다.

• 농촌지도와개발
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• 제8권2호
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• pp.201-208
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• 2001

The purpose of this study was to review the current studies on community attachment and its related variables to suggest directions for community attachment studies in Korea. Specific objectives of the study were to search the current studies on community attachment, to search for the significant variables related to community attachment, and to draw implications for community development in Korea. The major findings of the study were as follows; 1) Current studies on community attachment used individual characteristic variables such as length of residence in the community, age, size of population and density as major independent variables. 2) Studies on community attachment used community participation, social and cultural environment as major dependent variables, however, both independent variables and dependent variables were used interchangeably in many cases. 3) Recent studied on community attachment employed community economic and cultural variables, however, studies on community attachment in Korea was relatively limited in terms of quantity as well as quality. 4) Further research on community attachment should be conducted by utilizing various independent and dependent variables in various communities to increase the community attachment in rural and urban communities to further strengthen community development in Korea.

• The Journal of Asian Finance, Economics and Business
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• 제5권2호
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• pp.53-61
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• 2018

Corporate governance has received massive attention in academic research nowadays due to several recent corporate failures. Inefficiency of corporate governance mechanisms have driven the minds of the researchers and the policy makers to look with more insights into this area. Board composition, as part of corporate governance mechanism, plays a significant role to achieve company's goals or objectives and ensure transparency and accountability. The objective of this study is to find out the efficiency of board composition through board size, independent directors and female directors on firm performance in the listed manufacturing firms of Bangladesh. In this study, a sample of 162 firm years are considered as the sample during the period of 2011 to 2016. This study finds that large board is the significant explanatory variable in improving firm performance. This study also shows that board independence and female directors have no significant association with firm performance which implies that instrument of corporate governance mechanism particularly board composition is very weak. This study recommends that code of corporate governance, specially the role of independent directors and female directors, should be reformed in the light of cultural and institutional context along with the effective enforcement.

• 대한전자공학회논문지SD
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• 제38권2호
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• pp.145-153
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• 2001

조합회로에 대한 ATPG 알고리듬이 효율적으로 100%의 고장 검출율을 달성할 수 있게 되어 감에 따라서 고장 검출율을 그대로 유지한 상태에서 테스트 패턴을 줄이는 압축 기법의 중요성이 점차로 부각되고 있다. 본 논문에서 제시하는 알고리듬은 고장들간의 독립과 양립 관계에 기초해서, 압축된 테스트 패턴을 위해서는 양립할 수 있는 고장 집합의 크기를 크게 해야 하므로, 고장-패턴 쌍과 고장들간의 독립과 양립 관계를 이용해서 고장-패턴 쌍의 트리 구조를 생성하였다. 이 고장-패턴 트리를 바탕으로 해서 효율적으로 압축된 테스트 패턴을 생성할 수 있었고, ISCAS 85와 ISCAS 89 측정 기준 회로에 대한 결과로 제시된 알고리듬의 우수성을 검증하였다.

• Current Optics and Photonics
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• 제4권6호
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• pp.558-565
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• 2020

A wavelength-independent optical sensor based on an asymmetric Mach-Zehnder interferometer (AMZI) is proposed. The optical sensor based on an AMZI is very sensitive to wavelength, and wavelength drift will lead to measurement error. The optical sensor is compensated to reduce its dependence on wavelength. The insensitivity of the optical sensor to wavelength mainly depends on the compensation structure, which is composed of an AMZI cascaded with another AMZI and can compensate the wavelength drift. The influence of wavelength drift on the optical sensor can be counteracted by carefully designing the size parameters of the compensation structure. When the wavelength changes from 1549.9 nm to 1550.1 nm, the error after compensation can be lower than 0.066%. Furthermore, the effect of fabrication tolerance on compensation results is analyzed. The proposed compensation method can also be used to compensate the drift of other parameters such as temperature, and can be applied to the compensation of other interference-based optical devices.

• 유통과학연구
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• 제12권7호
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• pp.77-88
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• 2014

Purpose - Based on the existing retail policy literature, this study aims to compare Korea with foreign countries, to propose better ideas for the Korean retail market. Research design, data, and methodology - It is necessary to analyze the existing retail regulations after categorizing them into several groups, depending on why governments have regulated retailers and the background for the retail policy. Results - Given that Korean retail regulations have focused on protecting conventional markets, comparing the retail policy objectives of South Korea and foreign countries is difficult. Conclusions - It is necessary examine how to protect independent stores, irrespective of store locations across the country. Rather than limiting the distance between traditional markets and the projected locations suggested by large retailers, various factors such as store size limit, opening and closing times, below-cost selling, land use planning, and competition tests are needed to protect small stores. Further, centralized authority for store operations should be delegated to local governments, to tackle the aggressive expansion of retail giants. To protect independent stores, political background is among the most important factors.

• 대한수학회보
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• 제50권2호
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• pp.611-626
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• 2013

In the paper we study the finite-time ruin probability in a general risk model with constant interest force, in which the claim sizes are pairwise quasi-asymptotically independent and arrive according to an arbitrary counting process, and the premium process is a general stochastic process. For the case that the claim-size distribution belongs to the consistent variation class, we obtain an asymptotic formula for the finite-time ruin probability, which holds uniformly for all time horizons varying in a relevant infinite interval. The obtained result also includes an asymptotic formula for the infinite-time ruin probability.