• Geomechanics and Engineering
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• 제33권5호
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• pp.439-451
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• 2023

The construction of shield tunnelling in urban sites is facing serious risks from complex and changeable underground conditions. Construction problems in the sand-clay mixed ground have been more reported in recent decades for its poor control of soil loss in tunnel face, ground settlement and supporting pressure. Since the limitations of observation methods, the conventional physical modelling experiments normally simplify the tunnelling to a plane strain situation whose results are not reliable in mixed ground cases which exhibit more complicated responses. We propose a new method for the study of the mixed ground tunnel through which mixed lays are simulated with transparent soil surrogates exhibiting different mechanical properties. An experimental framework for the transparent soil modelling of the mixed ground tunnel was established incorporated with the self-developed digital image correlation system (PhotoInfor). To understand better the response of face stability, ground deformation, settlement and supporting phenomenon to tunnelling excavation in the sand-clay mixed ground, a series of case studies were carried out comparing the results from cases subjected to different buried depths and mixed phenomenon. The results indicate that the deformation mode, settlement and supporting phenomenon vary with the mixed phenomenon and buried depth. Moreover, a stratigraphic effect exists that the ground movement around mixed face reveals a notable difference.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.697-700
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• 1999

Strengthening existing structure using the exterior steel wire is utilized because of their high adaptability and strengthening efficiency. In the practical aspect, the fixing methods, which are generally adopted have caused problems. A new method is not easily designed because of the weak points, a limit of tension stress, and complex transmit processes. To make up for the weak points in the current fixing method, tensile end bracket similar to a supporting plate has been developed, but the tensile end bracket was relatively big because of increasing length welded between the end plate and the resisting plate.

• ETRI Journal
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• 제25권5호
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• pp.369-378
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• 2003

Using the general switch management protocol on a multi-protocol label switching network, we present an efficient method for handling handovers. The proposed method directly changes an established path into a new path for supporting a handover. Our investigation reveals the effects of the proposed scheme and demonstrates that this method significantly reduces signaling costs and delays.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1994년도 FIFTH WESTERN PACIFIC REGIONAL ACOUSTICS CONFERENCE SEOUL KOREA
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• pp.957-962
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• 1994

Real-time RELP vocoder is implemented on the TMS320C25 DSP chip. The implemented system is IBM-PC add-on board and composed of analog in/out unit, DSP unit, memoy unit, IBM-PC interface unit and its supporting assembly software. Speech analyzer and synthesizer is implimented by DSP assembly software. Speech parameters such as LPC coefficients, base-band residuals, and signal gains is extracted by autocorrelation method and inverse filter and synthesized by spectral folding method and direct form synthesis filter in this board. And then, real-time RELP vocoder with 9.6Kbps is simulated by down-loading method in the DSP program RAM.

• 한국지반환경공학회 논문집
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• 제13권11호
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• pp.69-79
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• 2012

선지보 네일공법은 터널의 굴착 전에 지반을 보강하므로 기존 지보시스템에 의한 NATM공법에 비해 굴착과정에서 변위를 최소화할 수 있어 안정성과 시공효율을 높일 수 있는 장점이 있다. 본 연구에서는 지하수위가 높고 미고결지반으로 구성된 천층터널에 대해 선지보 네일공법의 적용성을 현장계측관리 사례을 통해 연구하였으며, 지반보강개념에서 선지보 네일공법의 메카니즘과 기존 지보시스템의 메카니즘을 비교 분석하였다. 상하분할 굴착과정에서 굴착단계별 변위증폭이 뚜렷이 관찰되는 기존 지보시스템에 비해 선지보 네일공법은 초기변위 이후 단계굴착별 변위증폭량이 작고 이내 수렴되는 경향을 보여 다단굴착으로 인한 영향이 미미한 것으로 분석되었다. 선지보 네일공법은 종래 NATM공법과 비교할 때 단계굴착 시 응력변화에 대해 민감하고 아칭효과가 발생되지 않는 취약한 지반 즉, 토사터널인 천층터널에서 그 적용성이 뛰어난 것으로 판단된다.

• 인터넷정보학회논문지
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• 제2권1호
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• pp.49-61
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• 2001

인터넷 사용의 대중화와 네트워크 기술의 발달로 인하여 일반 사용자에 대한 비디오 컨텐츠의 원활한 제공과 편리한 검색 방법이 절실히 요구되고 있는 실정이다. 따라서 본 논문에서는 인터넷 서비스를 지원하는 클립(clip)기반 비디오 검색 시스템을 설계 및 구현한다. 구현된 시스템은 비디오 컨텐츠 제공자의 원활한 서비스를 지원하는 내용기반 인덱싱 시스템과 사용자의 다양한 검색을 지원하는 웹 기반 검색 시스템으로 구성되어 있다. 인덱싱 시스템은 비디오 분할에 의한 대표 프레임 추출과 연관된 정보의 클러스터링에 의한 클립 파일 생성 및 클립단위의 비디오 데이터베이스 구축 방법으로 이루어진다. 검색 시스템은 키워드 질의에 의한 검색 방법과 대표 프레임의 2차원 브라우징 방법 및 클립의 내용을 실시간으로 볼 수 있는 방법으로 이루어진다. 결론적으로 제시된 방법들은 비디오 컨텐츠를 제공하는데 있어서 유용성을 보이며 또한 의도한 비디오 내용을 쉽게 찾을 수 있도록 해준다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.248-259
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• 2010

In the case of relatively good ground and construction condition in the deep excavation for the construction of subway, railway, building etc., flexible earth retaining systems are often used in an economical point of view. It is generally known that the mechanism of behavior in the flexible earth retaining system is relatively more complicated than the rigid earth retaining system. Moreover in the case of long span strut supporting system the analysis of strut axial force change becomes more difficult when the differences of ground condition and excavation work progress on both sides of excavation section are added. When deeper excavation than the specification or installation delay of supporting system is done or change of ground condition is faced due to the construction conditions during construction process, lots of axial force can be induced in some struts and that can threaten the safety of construction. This paper introduces one example of long span deep excavation where struts and rock bolts were used as a supporting system with flexible wall structure. The characteristics of ground deformation and strut axial force change, the measured data obtained during construction process, were analysed, the effects of relatively deeper excavation than the specification on one excavation side and rapid drawdown of ground water level on the other excavation side were deeply investigated from the viewpoint of mutual influences between ground deformations of both excavation sides and strut axial force changes. The effort of this article aims to improve and develop the technique of design and construction in the coming projects having similar ground condition and supporting method.

• 대한치과보철학회지
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• 제28권2호
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• pp.199-215
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• 1990

This study was to analyze the stress distribution of implant and supporting tissue in $Br{\aa}nemark$ osseointegration implant. The analysis has been conducted by using the axisymmetric finite element method and type of model according to crown material. Tests have been performed at 1 kg load on central fossa of crown portion. Each type of model was designed differently according to crown material. 1) Porcelain fused to metal crown(Model A) 2) Composite resin veneered crown(Model B) 3) Acrylic resin veneered crown(Model C) 4) Type III gold crown(Model D) The displacements and stresses of implant and supporting structures were analyzed to investigate the influence of the type of crown material. The results were obtained as follows : 1. Displacement of implant was shown uniformly downward displacement in all models and abutments were observed distally downward displacement. 2. In supporting tissues, stress was concentrated on the crest of compact bone and the spongy bone below implant. 3. The PFM and the type III gold crown showed the largest concentration of stress at the crest of compact bone and the spongy bone below implant, respectively. Acrylic resin artificial teeth and composite resin veneered crown indicated almost the same distribution of stress. 4. The gold screw, the abutment screw and the top of abutment showed the concentration of stress in implants of every model.

• 한국소음진동공학회논문집
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• 제15권3호
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• pp.251-258
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• 2005

The free vibration of a spinning flexible disk-spindle system supported by hydro dynamic bearings (HDB) in an HDD is analyzed by FEM. The spinning flexible disk is described using Kirchhoff plate theory and von Karman non-linear strain, and its rigid body motion is also considered. It is discretized by annular sector element. The rotating spindle which includes the clamp, hub, permanent magnet and yoke, is modeled by Timoshenko beam including the gyroscopic effect. The flexible supporting structure with a complex shape which includes stator core, housing, base plate, sleeve and thrust pad is modeled by using a 4-node tetrahedron element with rotational degrees of freedom to satisfy the geometric compatibility. The dynamic coefficients of HDB are calculated from the HDB analysis program, which solves the perturbed Reynolds equation using FEM. Introducing the virtual nodes and the rigid link constraints defined in the center of HDB, beam elements of the shaft are connected to the solid elements of the sleeve and thrust pad through the spring and damper element. The global matrix equation obtained by assembling the finite element equations of each substructure is transformed to the state-space matrix-vector equation, and the associated eigen value problem is solved by using the restarted Arnoldi iteration method. The validity of this research is verified by comparing the numerical results of the natural frequencies with the experimental ones. Also the effect of supporting structures to the natural modes of the total HDD system is rigorously analyzed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.572-578
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• 2003

The free vibration of a spinning flexible disk-spindle system supported by hydro dynamic bearings in a HDD is analyzed by FEM. The spinning flexible disk is described using Kirchhoff plate theory and von Karman non-linear strain, and its rigid body motion is also considered. It is discretized by annular sector element. The rotating spindle which includes the clamp, hub, permanent magnet and yoke, is modeled by Timoshenko beam including the gyroscopic effect. The flexible supporting structure with a complex shape which includes stator core, housing, base plate, sleeve and thrust pad is modeled by using a 4-node tetrahedron element with rotational degrees of freedom to satisfy the geometric compatibility. The dynamic coefficients of HDB are calculated from the HDB analysis program, which solves the perturbed Raynolds equation using FEM. Introducing the virtual nodes and the rigid link constraints defined in the center of HDB, beam elements of the shaft are connected to the solid elements of the sleeve and thrust pad through the spring and damper element. The global matrix equation obtained by assembling the finite element equations of each substructure is transformed to the state-space matrix-vector equation, and the associated eigenvalue problem is solved by using the restarted Arnoldi iteration method. The validity of this research is verified by comparing the numerical results of the natural frequencies with the experimental ones. Also the effect of supporting structures to the natural modes of the total HDD system is rigorously analyzed.