• Steel and Composite Structures
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• 제51권3호
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• pp.225-241
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• 2024

For several reasons, cold-formed steel (CFS) beams are often manufactured with holes. Nevertheless, because of holes, the reduction in the web area causes a decrease in the bending strength. Edge stiffeners are presently added around the holes to improve the bending strength of flexural members. Therefore, this research studies CFSZ-beams with stiffened holes and investigates how edge stiffener affects bending strength and failure modes. Nonlinear analysis was carried out using ABAQUS software and the developed finite element (FE) model was verified against tests from previous studies. Using the verified FE model, a parametric study of 104 FE models was conducted to investigate the influence of key parameters on bending strength of Z- sections. The results indicated that the effect of holes is less noticeable in very thin Z-sections. Moreover, adding edge stiffeners around the holes improves the flexural capacity of Z-beams and sometimes restores the original bending capacity. Because the computational techniques used to solve the CFS buckling mode with stiffened holes are still unclear, a numerical method using constrained and unconstrained finite strip method (CUFSM) software was proposed to predict the elastic distortional buckling moment for a wide variety of CFSZ-sections with stiffened holes. A numerical method with two procedures was applied and validated. Upon comparison, the numerical method accurately predicted the distortional buckling moment of CFS Z-sections with stiffened holes.

• 아시안잔디학회지
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• 제11권4호
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• pp.295-301
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• 1997

The cycle of heavy metal, copper, was investigated in dynamic grassland ecosystems at a steady state in a Zoysia japonica and a Miscanthus sinensis ecosystem in Mt Kwanak, Korea. Total average storage amounts in Z. japonica and M sinensis grasslands were copper 23.92mg /$m^2$ and 51.82mg /$m^2$ respectively. Estimates of decay constants for based on experimental and mathematical model, were 0.18 in Z. japonica grassland, and 0.30 in M sinensis grassland. Decay half time of copper were 3.85 years in Z. japonica grassland and 2.31 years in A'. sinensis grassland. 95% decay times of initial copper amounts in Z. japonica and A'. sinensis were 16.68 and 9.99 years. Needed times to decay almost all of elements in Z. japonica and M sinensis grassland were 27.80 years and 16.65 years respectively. The copper was losed more rapidly in M. sinensis than in Z. japonica grassland.

• 한국정밀공학회지
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• 제12권5호
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• pp.77-87
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• 1995

In-process detection of drill wear is one of the most important technoligies for automatic, unmaned machining systems. In this study, an on-line drill wear estimation model based on spindle/Z-axis motor currents generated during the drilling process is proposed. The theoretical model is obtained by integrating the drilling process model and the servomechanism model. The drilling process model describes the relationship of drill wear and drilling torque/ thrust force, whereas the servomechanism model describes the relationship of drilling torque/ thrust force applied to motor and spindle/Z-axis motor current. Evaluation tests have shown that the proposed model is a good real-time estimator for drill wear.

• 한국멀티미디어학회논문지
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• 제7권11호
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• pp.1620-1629
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• 2004

접근제어의 목적은 컴퓨팅 자원 및 통신 정보자원 등을 부당한 사용자로부터 사용되거나, 수정, 노출 파괴와 같은 비합법적인 행위로부터 보호하는데 있다. 대표적인 보안 정책 중에서 Biba모델은 정보의 무결성을 보장하지만 상업적인 환경에 적용되기는 다소 미흡하며, 역 할기반접근제어 정책은 상업적인 측면의 보안정책에 적용이 가능하지만 접근되는 객체의 중요도에 따른 등급이 고려되어 있지 않아 정보의 무결성을 해칠 우려가 있다. 본 논문에서는 기존의 역할 그래프 모델에 무결성 등급을 갖는 사용자와 객체를 배정하여 주체의 무결성 등급과 역할에 관련된 객체의 무결성 등급에 따라 권한을 부여하므로 수많은 접근권한을 관리하는데 융통성을 제공할 뿐 아니라 정보의 무결성을 보장한다. 또한, 세분화된 역할들의 제약조건들을 명세 언어인 Z를 이용해 정형화된 구조로 명확하게 표현함으로써 접근제어정책에 대한 설계 및 구현시 시간과 비용 절감효과를 기대할 수 있다.

• 정보보호학회논문지
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• 제7권3호
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• pp.79-94
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• 1997

분산 객체 시스템에서 보안 기술과 객체지향 기술의 통합은 중요한 요소이기 때문에 OMG(Object Management Group)에서는 객체 시스템에서 보안성을 다루기 위한 표준 보안 서비스 규격으로 CORBA(Common Object Request Broker Architecture) 보안 참조 모델(security reference model)을 제시하였다. CORBA 보안 참조 모델에서 접근 제어 기능은 특정 구현 메카니즘에 종속되지 않는 독립적인 개념으로 정의되고 있으며, 또한 보안 특성의 의미가 완전하게 기술되지 않는다. 이는 구현자와 사용자가 상호 일치되지 않은 개념을 갖을 가능성을 내포한다 따라서 본 논문에서는 CORBA 보안참조 모델에 기술된 접근 제어 기능이 갖는 의미가 정확히 기술될 수 있도록 집합론에 기초하는 정형화 언어인 Z 언어의 스키마 구조를 이용하여 CORBA 접근 제어 모델을 정형화한다.

• Journal of Power Electronics
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• 제17권3호
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• pp.610-620
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• 2017

The Finite Control Set-Model Predictive Controller (FCS-MPC) for quasi Z-Source Inverters (qZSIs) is designed to reduce the number of sensors by proposing a current observer for the inductor current. Unlike the traditional FCS-MPC algorithm, the proposed model removes the inductor current sensor and observes the inductor current value based on the deposited prior optimized state as well as the capacitor voltage during this state. The proposed observer has been validated versus a typical MPC. Then, a comparative study between the proposed Modified Finite Control Set-Model Predictive Controller (MFCS-MPC) and a linear PID controller is provided under the same operating conditions. This study demonstrates that the dynamic response of the control objectives by MFCS-MPC is faster than that of the PID. On the other hand, the PID controller has a lower Total Harmonic Distortion (THD) when compared to the MFCS-MPC at the same average switching. Experimental results validate both methods using a DSP F28335.

• 유통과학연구
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• 제17권10호
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• pp.61-71
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• 2019

Purpose - This study aims to explore the impact of factors on Korean consumer goods purchase decision of Vietnam's Generation Z. Research design, data, and methodology - A mixed research method was utilized in this study including focus group, in-depth interview, pilot study, and official study. The conceptual model and hypothesis were tested using data collected cross-sectional by questionnaire, from a sample of 439 respondents, by both electronic and paper surveys with non-probability and convenience sampling. The SPSS 20 and AMOS 20 software were employed to analyze the data. Results - Results showed that Vietnam's Generation Z was strongly impacted by social media, Hallyu, country of origin, social norms, and perceived usefulness. Besides, Korean consumer goods purchase decision of Vietnam's Generation Z also were impacted by intermediary factors such as trust, social norms, product involvement, perceived quality, perceived usefulness, attitude, and buying intention. There were differences in factors affecting the purchase decision of the boy and girl Generation Z group. Conclusions - The factors impacting on Korean consumer goods decision of Vietnam's Generation Z are very important for Korean firms and government. The findings provide Korean firms opportunity for appropriate to be carried out factors impacting Korean consumer goods to generation Z in Vietnam successful.

• International journal of advanced smart convergence
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• 제11권3호
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• pp.132-141
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• 2022

We look at the rocket life stages of NaverZ's metaverse platform scaling and investigate the ignition and scale-up stage of its metaverse platform brand, Zepeto based on the Rocket Model (RM). The results are derived as follows: Firstly, NaverZ shows the event strategy by collaborating with K-pops, the piggybacking strategy by utilizing other SNSs, and the VIP strategy by investing in game and entertainment content genres in the 'attract' function. In the second 'match' function, based on the matching rule of Zepeto, the users can generate their own characters and "World" with Zepeto Studio. However, for strengthening the matching quality, NaverZ is investing in the artificial intelligence (AI) based companies consistently. In the 'connect' function, NaverZ's maximization of the positive interaction is possible by inducing feed activities in Zepeto & other SNSs and by uploading attractive content for viral effects in the ignition. For facilitating this, NaverZ expands the scale to other continents like Southeast Asia and Middle East with the localization strategy inclusive investment. Lastly, in the 'transact' function, based on three monetization experiments like Coin & ZEM, user generated content (UGC) fee, and advertising revenue in the ignition, NaverZ starts to invest in NFT platforms and abroad blockchain companies.

• 한국지구과학회지
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• 제26권7호
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• pp.706-713
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• 2005

엘니뇨현상과 관련된 해양 아표층 변동성을 조사하기 위해 1980년부터 2004년까지의 적도 해역의 20도 등온선 깊이(Z20)와 난수질량(WWV) 자료를 분석하였다. 주성분 분석, 합성 분석 및 교차상관 분석 결과, 아표층 시계열 자료는 Nino3.4 SST와 유의미한 시간 지연을 가지고 강한 상관성을 보였다. 이 결과는 아표층 해양 변수가 엘니뇨현상에 유용한 예측 인자임을 시사한다. 분석된 결과를 근거로 1996년부터 2004년까지 Nino3.4 SST를 예측하기 위해 신경망 예측 모델을 구성하였다. 해상풍을 입력 자료로 사용하였을 경우 보다 WWV를 적용하였을 때 3개월 이하의 단기 예측을 제외하고 모든 예측 시간에서 더 우수한 예측력을 보였으며, 5-8개월의 예측에 있어서는 기존의 여러 통계 모델 결과보다 예측 성능이 우수함을 확인하였다.

• Communications for Statistical Applications and Methods
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• 제5권3호
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• pp.935-944
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• 1998

This paper investigates the problem of goodness of fit tests for no effect model. The proposed test statistic $Z_{mn}$ is obtained by multiplying constant on the model free curve estimation techniques. The small and large sample properties of$Z_{mn}$ are investigated and the good results of power studies for the proposed test are illustrated.