• 제목/요약/키워드: hurdle model

검색결과 31건 처리시간 0.024초

Risk Prediction Using Genome-Wide Association Studies on Type 2 Diabetes

  • Choi, Sungkyoung;Bae, Sunghwan;Park, Taesung
    • Genomics & Informatics
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    • 제14권4호
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    • pp.138-148
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    • 2016
  • The success of genome-wide association studies (GWASs) has enabled us to improve risk assessment and provide novel genetic variants for diagnosis, prevention, and treatment. However, most variants discovered by GWASs have been reported to have very small effect sizes on complex human diseases, which has been a big hurdle in building risk prediction models. Recently, many statistical approaches based on penalized regression have been developed to solve the "large p and small n" problem. In this report, we evaluated the performance of several statistical methods for predicting a binary trait: stepwise logistic regression (SLR), least absolute shrinkage and selection operator (LASSO), and Elastic-Net (EN). We first built a prediction model by combining variable selection and prediction methods for type 2 diabetes using Affymetrix Genome-Wide Human SNP Array 5.0 from the Korean Association Resource project. We assessed the risk prediction performance using area under the receiver operating characteristic curve (AUC) for the internal and external validation datasets. In the internal validation, SLR-LASSO and SLR-EN tended to yield more accurate predictions than other combinations. During the external validation, the SLR-SLR and SLR-EN combinations achieved the highest AUC of 0.726. We propose these combinations as a potentially powerful risk prediction model for type 2 diabetes.

전산유체역학모형에 근거한 미기상 바람환경 영향평가 시스템 (An Environmental Impact Assessment System for Microscale Winds Based on a Computational Fluid Dynamics Model)

  • 김규랑;구해정;권태헌;최영진
    • 환경영향평가
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    • 제20권3호
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    • pp.337-348
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    • 2011
  • Urban environmental problem became one of major issues during its urbanization processes. Environmental impacts are assessed during recent urban planning and development. Though the environmental impact assessment considers meteorological impact as a minor component, changes in wind environment during development can largely affect the distribution pattern of air temperature, humidity, and pollutants. Impact assessment of local wind is, therefore, a major element for impact assessment prior to any other meteorological impact assessment. Computational Fluid Dynamics (CFD) models are utilized in various fields such as in wind field assessment during a construction of a new building and in post analysis of a fire event over a mountain. CFD models require specially formatted input data and produce specific output files, which can be analyzed using special programs. CFD's huge requirement in computing power is another hurdle in practical use. In this study, a CFD model and related software processors were automated and integrated as a microscale wind environmental impact assessment system. A supercomputer system was used to reduce the running hours of the model. Input data processor ingests development plans in CAD or GIS formatted files and produces input data files for the CFD model. Output data processor produces various analytical graphs upon user requests. The system was used in assessing the impacts of a new building near an observatory on wind fields and showed the changes by the construction visually and quantitatively. The microscale wind assessment system will evolve, of course, incorporating new improvement of the models and processors. Nevertheless the framework suggested here can be utilized as a basic system for the assessment.

De-Centralized Information Flow Control for Cloud Virtual Machines with Blowfish Encryption Algorithm

  • Gurav, Yogesh B.;Patil, Bankat M.
    • International Journal of Computer Science & Network Security
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    • 제21권12호
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    • pp.235-247
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    • 2021
  • Today, the cloud computing has become a major demand of many organizations. The major reason behind this expansion is due to its cloud's sharing infrastructure with higher computing efficiency, lower cost and higher fle3xibility. But, still the security is being a hurdle that blocks the success of the cloud computing platform. Therefore, a novel Multi-tenant Decentralized Information Flow Control (MT-DIFC) model is introduced in this research work. The proposed system will encapsulate four types of entities: (1) The central authority (CA), (2) The encryption proxy (EP), (3) Cloud server CS and (4) Multi-tenant Cloud virtual machines. Our contribution resides within the encryption proxy (EP). Initially, the trust level of all the users within each of the cloud is computed using the proposed two-stage trust computational model, wherein the user is categorized bas primary and secondary users. The primary and secondary users vary based on the application and data owner's preference. Based on the computed trust level, the access privilege is provided to the cloud users. In EP, the cipher text information flow security strategy is implemented using the blowfish encryption model. For the data encryption as well as decryption, the key generation is the crucial as well as the challenging part. In this research work, a new optimal key generation is carried out within the blowfish encryption Algorithm. In the blowfish encryption Algorithm, both the data encryption as well as decryption is accomplishment using the newly proposed optimal key. The proposed optimal key has been selected using a new Self Improved Cat and Mouse Based Optimizer (SI-CMBO), which has been an advanced version of the standard Cat and Mouse Based Optimizer. The proposed model is validated in terms of encryption time, decryption time, KPA attacks as well.

Foreign Direct Investment -Small and Medium Enterprises Linkages and Global Value Chain Participation: Evidence from Vietnam

  • NGUYEN, Thi Minh Thu;NGUYEN, Thi Tuong Anh;NGUYEN, Thi Thuy Vinh;PHAM, Huong Giang
    • The Journal of Asian Finance, Economics and Business
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    • 제8권3호
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    • pp.1217-1230
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    • 2021
  • Using a multinomial logit model with the panel-data set of Vietnam manufacturing firms, this paper investigates the impacts of foreign direct investment (FDI) - small and medium enterprises (SMEs) linkages and other factors on SMEs' participation in the global value chain (GVC). We consider GVC firms are those engaging in any of the three modes including (i) using domestic inputs to export (D2E), (ii) using imported inputs to produce for the domestic market (I2P), (iii) using imported inputs to export (I2E). We discover that FDI-SME linkages statistically encourage Vietnamese SMEs to integrate into the GVC via I2P and I2E, while no statistical association between FDI-SME linkage and D2E participation is found. GVCs participation likelihood is also positively correlated with the introduction of new product introduction. The establishment of firms' production facilities in industrial zones and foreign ownership are both reported to be significantly decisive factors to SMEs' decisions on GVC participation. Besides, there is a strong association between firms' attributes, i.e. employment, capital intensity as well as financial access, and their participation in the GVC. Local governance quality (proxied by the Provincial Competitiveness Index) and the share of skilled labor at the province-level can facilitate firms' integration into GVCs, while greater market concentration may be a hurdle to such potential.

기계산업의 제품혁신 성과 및 결정요인에 관한 연구 (The Study on the Performance and Determinants of Product Innovation in Machinery Industry)

  • 봉강호;박준영;박재민
    • 한국산학기술학회논문지
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    • 제19권9호
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    • pp.427-434
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    • 2018
  • Pavitt(1984)과 Malerbar(2002)의 지적과 같이 혁신은 산업의 특성에 따라 다른 면모를 갖는다. 이 같은 관점에서 기계산업의 혁신을 다룬 기존 연구들은 주로 전체 제조업과 비교한 산업간 차이를 규명하는 데 초점을 두었다. 기계산업과 같은 기술 숙련집약적 산업에서의 혁신은 특히 다른 산업의 혁신과 상이한 특성과 메커니즘을 가질 것으로 예상되는 반면, 논의는 부족한 실정이다. 이에 본 연구에서는 기계산업의 제품혁신이 어떠한 요인들에 의해 결정되는 지를 다룸에 있어 제품혁신의 성과를 양적 측면과 질적 측면으로 구분해 접근하였고, 특히 Heckman 2단계 모형과 허들음이항 모형을 적용해 기업의 혁신활동에 수반되는 단계적 선택과정을 명시적으로 분석에 반영하였다. 분석 결과, 기계산업의 제품혁신에 있어 제품의 품질 및 성능향상 및 특허에 영향을 미치는 요인은 서로 상이하였으며, 문지방효과와 혁신의 강도 역시 구분되는 것으로 나타났다. 이는 결과적으로 기계산업은 연구개발 역량을 일정 수준 이상 축적하고 외부의 혁신을 효과적으로 조직 내 체화하고, 조직 구성원들에 대한 동기부여가 성과 향상에 중요한 역할을 수행한다고 하겠다.

프로세스 관점에서의 기술혁신 및 고용성과에 관한 연구 : 중소기업을 중심으로 (A Study on Technological Innovation and Employment Performance from the Perspective of Process : Focused on Small and Medium Sized Enterprises)

  • 봉강호;박재민
    • 기술혁신학회지
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    • 제21권4호
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    • pp.1508-1535
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    • 2018
  • 기업들에 있어서 고용은 혁신활동의 결과를 바탕으로 하는 연속된 의사결정과정이다. 따라서 기술혁신을 통한 고용성과를 살펴봄에 있어서 이 같은 관계성을 명시적으로 분석에 고려할 필요가 있다. 이러한 문제의식을 바탕으로 본 연구에서는 중소기업의 기술혁신과 고용효과의 관계를 선행 연구와 같이 단일방정식을 추정하는 순위로짓(ordered logit) 모형으로 분석할 뿐 아니라, 연립방정식을 추정하는 외견무관회귀(SUR) 모형을 활용하여 실제 동시적으로 수행되어지는 기술경영 과정의 상관성을 반영하여 기업의 혁신활동과 기술혁신 성과, 보상제도 그리고 고용 창출의 구조적 관계를 분석하고자 하였다. 분석 결과, 보상제도의 시행은 기술개발 및 기술사업화 성과를 높이고, 이것은 다시 기업의 고용을 촉진하는 구조적 관계를 확인할 수 있었다. 특히 고용성과에 있어 기술개발 뿐 아니라 사업화 성과가 일종의 허들로 작용한다는 점에서 기술혁신을 프로세스 관점에서 관리할 때 기업의 고용성과는 높아진다고 볼 수 있겠다.

Butanol 생합성 Clostridium 속 미생물 대사공학용 게놈 편집 도구 개발 (Development of Genome Engineering Tools for Metabolic Engineering of Butanol-producing Clostridium Species)

  • 우지은;김민지;이지원;서효주;이상엽;장유신
    • KSBB Journal
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    • 제31권4호
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    • pp.193-199
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    • 2016
  • Global warming caused from the heavy consumption of fossil fuel is one of the biggest problems to be solved. Biofuel has been gained more attention as an alternative to reduce the consumption of fossil fuel. Recently, butanol produced from the genus Clostridium has been considered as one of the promising alternatives for gasoline, fossil based fuel. Nevertheless, the lack of the genome-engineering tools for the genus Clostridium is the major hurdle for the economic production of butanol. More recently, genome engineering tools have been developed for metabolic engineering of butanol-producing Clostridium species, which includes genome scale network model and genome editing tools on the basis of mobile group II introns and CRISPR/Cas system. In this study, the genome engineering tools for butanol-producing Clostridium species have been reviewed with a brief future perspective.

CD7-Specific Single Chain Antibody Mediated Delivery of siRNA to T Cells Inhibits HIV Replication in a Humanized Mouse Model

  • Ban, Hong-Seok;Kumar, Priti;Kim, Na-Hyun;Choi, Chang-Son;Shankar, Premlata;Lee, Sang-Kyung
    • 한국미생물학회:학술대회논문집
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    • 한국미생물학회 2008년도 International Meeting of the Microbiological Society of Korea
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    • pp.62-64
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    • 2008
  • A major hurdle to the development of RNA interference as therapy for HIV infection is the delivery of siRNA to T lymphocytes which are difficult cells to transfect even in vitro. We have employed a single chain antibody to the pan T cell surface antigen CD7 was conjugated to an oligo-9-arginine peptide (scFvCD7-9R) for T cell-specific siRNA delivery in NOD/SCIDIL2${\gamma}$-/- mice reconstituted with human peripheral blood lymphocytes (Hu-PBL). Using a novel delivery, we first show that scFvCD7-9R efficiently delivered CD4 siRNA into human T cells in vitro. In vivo administration to Hu-PBL mice resulted in reduced levels of surface CD4 expression on T cells. Mice infected with HIV-1 and treated on a weekly basis with scFvCD7-9R-siRNA complexes targeting a combination of viral genes and the host coreceptor molecule CCR5 successfully maintained CD4/CD3 T cell ratios up to 4 weeks after infection in contrast to control mice that displayed a marked reduction in CD4 T cell numbers. p24 antigen levels were undetectable in 3 of the 4 protected mice. scFvCD7-9R/antiviral siRNA treatment also helped maintain CD4 T cell numbers with reduced plasma viral loads in Hu-PBL mice reconstituted with PBMC from donors seropositive for HIV, indicating that this method can contain viral replication even in established HIV infections. Our results show that scFvCD7-9R could be further developed as a potential therapeutic for HIV-1 infection.

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국립대학 공간 활용과 관리에 관한 조사연구 (A Survey Study on Space Use and Management at National Universities)

  • 이화룡;조창희;류수훈;김태형;류춘근;서붕교
    • 교육시설 논문지
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    • 제21권3호
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    • pp.3-10
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    • 2014
  • A study of facility securement and space utilization at national universities in Korea was conducted in order to help develop an efficient model for space management at national universities going forward. For the study, 36 national universities were asked to submit answers to a questionnaire on usage of campus facilities in 2013. We then analyzed the results of space management for the 27 universities that participated in the questionnaire in each of the past three years (2011-2013). Lastly, we conducted an awareness test on the space utilization policies and space management for these universities. The results are as follows. First, the aggregate average score for space utilization over the past three years is 74.06. The annual average score increased year-over-year and then decreased; it was 69.44 in 2011, 80.68 in 2012, and 72.05 in 2013. A decline in the sense of responsibility of universities to effectively manage space appears to be a factor in the decrease. Second, with 53% of respondents in agreement, treatment of campus area as private space appears to be the biggest hurdle for efficient space management. As such, a plan to foster a more communal view of campus facility area is required. Third, resistance from constituents to existing guidelines for space allocation on campuses appears to be limited (78.1% of respondents answered the guidelines currently in place were average, satisfactory, or very satisfactory). We believe this result points to a mutual understanding forming amongst constituents regarding guidelines on space allocation on campus.results of satisfaction research: the users are generally satisfied with education and student.

무선인지 멀티홉 릴레이 네트워크의 시스템 스루풋 (System Throughput of Cognitive Radio Multi-hop Relay Networks)

  • 임룰하싼;노창배;송주빈
    • 대한전자공학회논문지TC
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    • 제46권4호
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    • pp.29-39
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    • 2009
  • 제한된 전파 스펙트럼 자원은 전파 네트워크의 빠른 발전에 큰 장벽이 되고 있다. 대부분의 전파 스펙트럼은 면허 방식으로 분배되어 서비스에 이용되고 있다. 반면 비면허 방식으로 분배된 전파 스펙트럼은 전파를 이용한 서비스와 기술을 크게 향상하는데 큰 기여를 하였다. 최근에 무선인지 기술은 이러한 전파 스펙트럼 자원의 부족을 해결하기 위한 기술로써 주목받고 있다. 이 기술은 전파 스펙트럼을 효율적으로 사용 가능하도록 한다. 한편으로 멀티홉 기술이 에드홀 및 피어 투 피어 네트워크에서 집중적으로 연구되고 있으나 이동통신 네트워크에서 성능 향상을 위하여 멀티홉 기술의 연구는 최근에야 이루어지고 있다. 멀티홉 기술은 음영 지역에 고속의 데이터를 제공하고 적은 비용으로 서비스 영역을 효율적으로 확장할 수 있는 기술이다. 이동통신 시스템에서 스펙트럼 이용률을 극대화하는 무선인지 멀티홉 기술의 연구는 그 유용성에도 불구하고 아직까지 많지 않았다. 따라서 본 논문에서는 시스템 스루풋을 최대화 하는 무선인지 멀티홉 기술을 적용한 네트워크를 제안한다. 본 논문에서 제안된 시스템의 스루풋 성능을 주사용자와 부사용자의 전파 반경 및 이용률 파라메터와 같은 다양한 파라메터를 사용하여 해석적으로 모델링하고 수치해석을 통하여 제안된 시스템의 성능이 현재의 시스템에 비하여 크게 향상됨을 보였다.