• Asian Pacific Journal of Cancer Prevention
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• 제15권15호
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• pp.6411-6414
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• 2014

Background: A dense breast not only reduces the sensitivity of mammography but also is a moderate independent risk factor for breast cancer. The percentage of Western women with fat breast tissue is higher aged 40 years or older. To a certain extent, mammography as a first choice of screening imaging method for Western women of this group is reasonable. Hitherto, the frequency and age distribution of mammographic breast density patterns among Chinese women had not been characterized. The purpose of this study was to investigate the frequency and age distribution of mammographic breast density patterns among a group of Chinese screening women and breast cancer patients in order to provide useful information for age-specific guidelines for breast cancer screening in Chinese women. Methods: A retrospective review of a total of 3,394 screening women between August and December 2009 and 2,527 breast cancer patients between July 2011 and June 2012 was conducted. Descriptive analyses were used to examine the association between age and breast density. The significance of differences of breast density between the screening women and the breast cancer patients was examined using nonparametric tests. Results: There was a significant inverse relationship between age and breast density overall (r=-0.37, p< 0.01). Breast density of the breast cancer patients in the subgroups of 40-49 years old was greater compared with that of the screening women, the same in those aged 50-54 years and in those 55 years old or older, less than in the screening group. Conclusions: With regard to the Chinese women younger than 55 years old, the diagnostic efficiency of breast cancer screening imaging examinations may be potentially improved by combining screening mammography with ultrasound.

• Communications for Statistical Applications and Methods
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• 제11권3호
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• pp.619-629
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• 2004

Binomial group testing or composite sampling is often used to estimate the proportion, p, of positive(infects, defectives) in a population when that proportion is known to be small; the potential benefits of group testing over one-at-a-time testing are well documented. The literature has focused on maximum likelihood estimation. We provide two Bayes estimators and compare them with the MLE. The first of our Bayes estimators uses an uninformative Uniform (0, 1) prior on p; the properties of this estimator are poor. Our second Bayes estimator uses a much more informative prior that recognizes and takes into account key aspects of the group testing context. This estimator compares very favorably with the MSE, having substantially lower mean squared errors in all of the wide range of cases we considered. The priors uses a Beta distribution, Beta ($\alpha$, $\beta$), and some advice is provided for choosing the parameter a and $\beta$ for that distribution.

• 인터넷정보학회논문지
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• 제11권6호
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• pp.87-110
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• 2010

국내 기업의 우수 기술 관련 기밀 정보량은 늘어났지만 정보 유통의 디지털화로 유출 위험은 커지고 불법유출 경로를 파악하기가 매우 어려워서, 실제 유출 사례가 늘어감에도 막을 대책이 없어 재정적 피해는 점점 커지고 있다. 그러나 현재 문서보호 시스템은 저작물 보호 차원에서 설계되어 있어서, 합법적 사본이 유출될 경우 불법적 사용 방지 및 추적에 무방비이고, 내부자가 공모한 유출에는 대책이 전혀 없다는 것이 문제이다. 기업비밀의 특성상 폐쇄된 멀티캐스트 그룹 내 유통으로 제한하는 것이 적합하지만 그룹 기반 표준 프로토콜을 적용하여 기업비밀보호에 필요한 보호조건을 충분히 만족시키는 설계 연구가 없었다. 본 연구는 원천봉쇄 시스템 구조 설계 연구의 후속 연구로서 MSEC 기반 키-관리 프로토콜을 IGMP, SNMP와 접목하여 완전한 보호기능을 달성하는 비밀정보 유통 프로토콜을 제안하고, 프로토콜 구현의 단계적 시간 순서 차트까지 설계하였다. 본 연구는 비밀정보보호의 강력 보안조건인 암호화 유통원칙, 키와 정보 분리원칙, 반출시 처리와 저장의 분리원칙, 사용자와 호스트의 이중 인증 원칙을 적용한 키-관리 프로토콜 및 비밀정보 유통 프로토콜을 제안한다.

• Steel and Composite Structures
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• 제30권4호
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• pp.315-325
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• 2019

Double skin composite walls offer structural and economic merits over conventional reinforced concrete counterparts in terms of higher capacity, greater stiffness, and better ductility. This paper investigated the axial behavior of double skin composite walls with steel truss connectors. Full-scaled tests were conducted on three specimens with different height-to-thickness ratios. Test results were evaluated in terms of failure mode, load-axial displacement response, buckling loading, axial stiffness, ductility, strength index, load-lateral deflection, and strain distribution. The test data were compared with AISC 360 and Eurocode 4 and it was found that both codes provided conservative predictions on the safe side.

• 컴퓨터교육학회논문지
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• 제7권1호
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• pp.55-66
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• 2004

오늘날의 인터넷은 그룹 통신 모뎀인 멀티캐스트 서비스를 제공하고 있으며 멀티캐스트 통신의 보안을 유지하는 것이 중요하다. 멤버의 탈퇴는 그룹키 관리의 확장성 문제와 관련이 있다. 그룹의 한 멤버가 제거되면 새로운 그룹키를 생성하여 그룹의 나머지 모든 멤버들에게 전달되어야 한다. 새로운 키를 생성하여 분재하는 것은 많은 연산을 요구하므로 rekey하기 위하여 보내는 메시지의수와 복합키를 행성하기 위하여 연산비용을 최소화하는 것은 키 관리기법을 평가하는 중요한 기준이다. 주기적인 rekey는 멤버를 순차적으로 1개씩 제거하는 것보다 rekey에 대한 메시지의 수와 복합키의 연산 비용을 줄일 수 있다. 본 논문에서는 그룹에서 제거될 멤버들간의 해밍거리가 임계치보다 작은 멤버들만 동시에 제거한다. 여러 개의 멤버를 제거할 때 라운드 조정 알고리즘을 수행하면 rekey하기 위한 메시지의 수와 복합키를 생성하기 위한 비용을 줄일 수 있는 이점이 있다.

• 정보보호학회논문지
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• 제17권2호
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• pp.3-17
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• 2007

본 논문에서는 IGMP(Internet group management protocol)를 부당하게 사용함으로써 발생하는 DoS(Denial-of Service) 공격으로부터 멀티캐스트 분배트리를 보호하기 위해 IGMP의 보안관련 기능을 확장시킴으로써 수신자 접근제어기법을 제안하였다. IP 멀티캐스트 애플리케이션의 상업적인 적용을 위해 채택된 특정 네트워크와 비즈니스 모델을 기반으로, CP(Content Provider), NSP(Network Service Provider), 그룹멤버(group member)에 대한 회계 및 청구와 함께 제안 접근제어기법의 부트스트래핑(bootstrapping)을 위해 키 관리기법 또한 제시하였다.

• ALGAE
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• 제26권4호
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• pp.299-315
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• 2011

The morphology, taxonomy, and distribution of species belonging to the diatom family Rhizosoleniaceae were studied from the marine coastal waters of Korea. Rhizosolenid diatom taxa were collected at 30 sites from September 2008 to February 2010 and were analyzed by light and scanning electron microscopy. We identified 6 rhizosolenid genera, including Rhizosolenia, Proboscia, Pseudosolenia, Neocalyptrella, Guinardia, and Dactyliosolen. We describe 5 genera in this study, except Rhizosolenia. Five genera were compared in detail with congeneric species. Six genera within the family Rhizosoleniaceae were divided into two groups based on morphological diagnostic characters including valve shape, areolae pattern, the shape of external process, and girdle segments in the column. The first group had a conoidal valve and loculate areolae, which comprised Rhizosolenia, Proboscia, Pseudosolenia, and Neocalyptrella, and the second group of Guinardia and Dactyliosolen showed a flat or rounded valve and poroid areolae. Important key diagnostic characters were based on valve shape, areolae pattern on the segment, external process, position of the tube, and the valve margin. D. phuketensis was new to Korean coastal waters.

• 한국수산과학회지
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• 제54권1호
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• pp.80-89
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• 2021

In Korea, marine fish landed at ports are randomly sampled on a periodic basis (e.g., daily or weekly), and body sizes (e.g., lengths and weights) of those sampled fish are measured. The motivation for our study is whether or not such measurements reflect the size distribution, especially the length distribution of fish landed (= a population), because such length measurements are key data for a length-based assessment model. The current sampling method is to sample fish landed at ports by body size group (e.g., very small, small, medium, large, very large), using the sampling weights as the number of boxes by body size group. In this study, we showed that length composition data about fish sampled by the current method did not represent the length frequency distribution of the fish landed, and suggested that an alternative sampling method should be applied of using the sampling weights as the number of fish landed by body size group. We also introduced a method for determining an appropriate sample size.

• 정보보호학회논문지
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• 제18권5호
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• pp.103-113
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• 2008

IEEE 802.11 기반 무선랜에서 실시간으로 대용량의 데이터 전송이 필요한 멀티미디어 서비스를 원활히 제공하기 위해서는 빠른 핸드오프가 필수적이다. 핸드오프 지연을 줄이기 위해서는 인증 지연을 최소화하는 것이 필요하며, 이를 위해 Mishra 등은 예측을 통해 표준 기법의 인증 지연을 개선하였으며, 박찬일 등은 Blom의 키 사전분배 기법을 이용하여 인증 지연을 개선하고자 하였다. 이 논문에서는 Bresson 등의 그룹키 프로토콜을 활용한 개선된 형태의 인증 프로토콜을 제안한다. 제안하는 프로토콜의 경우 네트워크에 참여한 경험이 있는 이동 노드는 해시 연산만을 사용하여 액세스 포인트와 빠르게 상호인증을 수행할 수 있어 박찬일 등의 기법보다 효율적이며. Mishra 등의 예측 기법까지 적용하면 매우 빠른 상호인증을 제공할 수 있다.

• Geomechanics and Engineering
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• 제28권6호
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• pp.613-624
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• 2022

A study of the evolution of overburden fractures under the solid-fluid coupling state was conducted based on the geological and mining characteristics of the coal seam depth, weak strata cementation, and high-intensity mining in the mining areas of West China. These mining characteristics are key to achieving water conservation during mining or establishing groundwater reservoirs in coal mines. Based on the engineering background of the Daliuta Coal Mine, a non-hydrophilic simulation material suitable for simulating the weakly cemented rock masses in this area was developed, and a physical simulation test was carried out using a water-sand gushing test system. The study explored the spatial distribution and dynamic evolution of the fractured zone in the mining overburden under the coupling of stress and seepage. The experimental results show that the mining overburden can be vertically divided into the overall migration zone, the fracture extension zone and the collapse zone; additionally, in the horizontal direction, the mining overburden can be divided into the primary fracture zone, periodic fracture zone, and stop-fracture zone. The scope of groundwater flow in the overburden gradually expands with the mining of coal seams. When a stable water inrush channel is formed, other areas no longer generate new channels, and the unstable water inrush channels gradually close. Finally, the primary fracture area becomes the main water inrush channel for coal mines. The numerical simulation results indicate that the overlying rock breaking above the middle of the mined-out area allows the formation of the water-conducting channel. The water body will flow into the fracture extension zone with the shortest path, resulting in the occurrence of water bursting accidents in the mining face. The experimental research results provide a theoretical basis for the implementation of water conservation mining or the establishment of groundwater reservoirs in western mining areas, and this theoretical basis has considerable application and promotion value.