• 한국건설관리학회논문집
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• 제7권1호
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• pp.110-118
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• 2006

현행 일괄입찰방식은 분담이행방식의 공동도급형태로 운영되고 있어, 참여업체간의 의사소통 부족으로 설계기술과 시공기술의 접목이라는 일괄입찰방식 본래의 취지를 살리지 못하고 있다. 또한 입찰을 통해 확정된 총액금액으로 설계가 진행되므로 실시설계단계에서 VE활동을 통한 원가절감 노력이 거의 이루어지지 않고 있는 실정이다. 이에 본 연구에서는 현행 설계시공일괄방식의 특성을 파악하고 설계VE 적용사례를 분석하여, 설계VE 적용의 문제점이 무엇인지를 파악한 후, 일괄입찰사업 수행절차에서 설계VE 적용의 효과를 극대화할 수 있는 파트너링의 활용방법 및 그 적용시기를 제안한다.

• 한국건설관리학회논문집
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• 제8권5호
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• pp.182-190
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• 2007

국내 중 소규모 건설 산업은 시공분야를 중심으로 발전하여 왔으며 소프트분야가 상대적으로 취약하다. 또한 다양한 발주 체계가 활용되지 못하는 문제점을 안고 진행되고 있다. 더욱이 현재 국내 건설 프로젝트들은 자금력과 기술력을 갖춘 대형 건설업체들이 경쟁 우위를 점하고 있어 중 소규모 건설업체들의 입지가 줄어들고 있다. 최근국내 외 건설시장의 대형화, 고도화와 함께 기술집약적인 공사가 늘어감에 따라 기술경쟁이 가능한 설계시공일괄(Design-Build)방식의 건설 산업이 늘어나고 있는 추세이며 규모가 작은 중 소건설기업의 상황에서는 더욱 건설시장에서 효과적인 경쟁력을 보유하여야 할 것으로 예상한다. 이에 본 연구는 디자인 빌드 방식의 성공요인과 중 소규모 프로젝트 사례조사를 한 후 AHP 분석을 통해 성공요인 도출 및 중요도 분석을 함으로써 중 소규모 건설업체의 디자인 빌드 방식의 성공적 수행을 위한 중점 관리요인을 제시하고자 한다. 그리하여 향후 중 소 건설업체의 발전과 생산성 향상을 위한 기반을 제공하고자 한다.

• Tribology and Lubricants
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• 제22권2호
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• pp.59-65
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• 2006

In hard disk drives as the head to disk spacing continues to decrease to facilitate recording densities, slider disk interactions have become much more severe due to direct contact of head and disk surfaces in both start/stop and flying cases. The slider disk interaction in CSS (contact-start-stop) mode is an important source of particle generation and tribocharge build-up. The tribocharge build-up in the slider disk interface can cause ESD (electrostatic discharge) damage. In turn, ESD can cause severe melting damage to MR or GMR heads. The spindle speed of typical hard disk drives has increased in recent years from 5400 rpm to 15000 rpm and even higher speeds are anticipated in the near future. And the increasing disk velocity leads to increasing disk acceleration and this might affect the tribocharging phenomena of the slider/disk interface. We investigated the tribocurrent/voltage build-up generated in HDD, operating at increasing disk accelerations. In addition, we examined the effects with relative humidity conditions and rest time. We found that the tribocurrent/voltage was generated during pico-slider/disk interaction and its level was about $3\sim16pA$ and $0.1\sim0.3V$, respectively. Tribocurrent/voltage build-up was reduced with increasing disk acceleration. Higher humidity conditions $(75\sim80%)$ produced lower levels tribovoltage/current. Therefore, a higher tribocharge is expected at a lower disk acceleration and lower relative humidity condition. Rest time affected the charge build-up at the slider-disk interface. The degree of tribocharge build-up increased with increasing rest time.

• The Journal of Advanced Prosthodontics
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• 제14권3호
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• pp.150-161
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• 2022

PURPOSE. The purpose of the study was to assess the influence of build orientations and density of support structures on the trueness of the 3D printed removable partial denture (RPD) frameworks. MATERIALS AND METHODS. A maxillary Kennedy class III and mandibular class I casts were 3D scanned and used to design and produce two 3D virtual models of RPD frameworks. Using digital light processing (DLP) 3D printing, 47 RPD frameworks were fabricated at 3 different build orientations (100, 135 and 150-degree angles) and 2 support structure densities. All frameworks were scanned and 3D compared to the original virtual RPD models by metrology software to check 3D deviations quantitatively and qualitatively. The accuracy data were statistically analyzed using one-way ANOVA for build orientation comparison and independent sample t-test for structure density comparison at (α = .05). Points study analysis targeting RPD components and representative color maps were also studied. RESULTS. The build orientation of 135-degree angle of the maxillary frameworks showed the lowest deviation at the clasp arms of tooth 26 of the 135-degree angle group. The mandibular frameworks with 150-degree angle build orientation showed the least deviation at the rest on tooth 44 and the arm of the I-bar clasp of tooth 45. No significant difference was seen between different support structure densities. CONCLUSION. Build orientation had an influence on the accuracy of the frameworks, especially at a 135-degree angle of maxillary design and 150-degree of mandibular design. The difference in the support's density structure revealed no considerable effect on the accuracy.

• 전산구조공학
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• 제22권5호
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• pp.44-51
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• 2009

• Journal of Korean Dental Science
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• 제12권1호
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• pp.13-19
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• 2019

Purpose: The aim of this study was to compare the flexural strength of provisional fixed dental prostheses which was three-dimensional (3D) printed by several build directions. Materials and Methods: A metal jig with two abutment teeth and pontic space in the middle was fabricated. This jig was scanned with a desktop scanner and provisional restoration was designed on dental computer-aided design program. On the preprocessing software, the build angles of the restorations were arranged at $0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, and $90^{\circ}$ and support was added and resultant structure was sliced to a thickness of $100{\mu}m$. Processed restorations were printed with digital light processing type 3D printer using poly methyl meta acrylate-based resin. After washing and post-curing, compressive loading was applied at a speed of 1 mm/min on a metal jig fixed to a universal testing machine. The maximum pressure at which fracture occurred was measured. For the statistical analysis, build direction was set as the independent variable and fracture strength as the dependent variable. One-way analysis of variance and Tukey's post hoc analysis was conducted to compare fracture strength among groups (${\alpha}=0.05$). Result: The mean flexural strength of provisional restoration 3D printed with the build direction of $0^{\circ}$ was $1,053{\pm}168N$; it was $1,183{\pm}188N$ at $30^{\circ}$, $1,178{\pm}81N$ at $45^{\circ}$, $1,166{\pm}133N$ at $60^{\circ}$, and $949{\pm}170N$ at $90^{\circ}$. The group with a build direction of $90^{\circ}$ showed significantly lower flexural strength than other groups (P<0.05). The flexural strength was significantly higher when the build direction was $30^{\circ}$ than when it was $90^{\circ}$ (P<0.01). Conclusion: Among the build directions $0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, and $90^{\circ}$ set for 3D printing of fixed dental prosthesis, an orientation of $30^{\circ}$ is recommended as an effective build direction for 3D printing.

• Transactions on Electrical and Electronic Materials
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• 제17권6호
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• pp.317-328
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• 2016

Over the past few decades, CMOS current comparators have been used in a wide range of applications, including analogue circuits, MVL (multiple-valued logic) circuits, and various electronic products. A current comparator is generally used in an ADC (analog-to-digital) converter of sensors and similar devices, and several techniques and approaches have been implemented to design the current comparator to improve performance. To this end, this paper presents a bibliographical survey of recently-published research on different current comparator topologies for low-power and high-speed applications. Moreover, several aspects of the CMOS current comparator are discussed regarding the design implementation, parameters, and performance comparison in terms of the power dissipation and operational speed. This review will serve as a comparative study and reference for researchers working on CMOS current comparators in low-power and high-speed applications.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2409-2414
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• 2002

The surfaces of prototypes become rough due to the stair-stepping which is the inevitable phenomenon in the Rapid Prototypes are not used only for the verification of feature. The grinding, coating, or the composition of them is a main operation in post-processing in which lots of costs and long build time are needed. The solution is proposed to increase the efficiency of rapid prototyping by minimizing or removing the composition of them is a main operation in post-processing in which lots of costs and long build time are needed. the solution is proposed to increase the efficiency of rapid prototyping by minimizing or removing the regions for post-processing. the factors to cause the surface roughness and their effects are analyzed through the experiments. Software modules are developed to predict the surface roughness of each face in the prototyping with the result. An experimental compensation method is developed to apply the modules to various RP equipments, materials and build styles. The build direction is searched with use of genetic algorithm to maximize the total areas of the surface of which roughness is better than the user-defined value.

• 한국실내디자인학회논문집
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• 제21권2호
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• pp.215-222
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• 2012

Design-build is expanding gradually in large construction projects over 10billion won, and continue to work in health care facilities is increasing in this way. This constructional method in health care facilities, despite the many advantages, many problems caused by design changes are being raised. Raises the question of design changes on the side of construction contract, such as approval systems have been studied in the field of construction. The purpose of this study design in aspects of architectural planning on changing the grasp of the issues outlined in the ITB and bid evaluation criteria through consideration of the basic plan for improvement guidelines and evaluation criteria is presented. In conclusion, Design build, according to the presence of existing users are more likely to lead to design changes. Thus, hospital architecture, depending on how it is considered that constructional methods. And evaluation items of ITB(Invitation To Bidder) for a large part of the change in the variables evaluated in the hospital building is not suitable for the design build. Instead, the overall shape of the building and department, unit type and size, vertical and horizontal parts of the circulation system in the shape of the building that does not change in structure and etc should be considered for evaluation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.50-53
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• 2003

Most companies use technologies such as stereolithography, selective laser sintering, and fused deposition modeling to make parts for such small consumer products as telephones, heads, and shoes. The largest part that the existing RP systems can make is only 600 mm in length. Because most RP systems build parts by depositing, solidifying, or sintering material point-by-point, making larger objects takes a long time. and in many cases, large objects won't fit the build size. A new effective thick-layered RP process. Transfer type Variable Lamination Manufacturing using expandable polystyrene foam (VLM-ST) has been developed with thick layers and sloped surfaces. In this paper, a scaledown model of F16 Fighter with the length of 800 mm is rapidly fabricated using the VLM-ST process. In order to build a CAD model of F16 larger than 600 mm in length, the approach in VLM-ST is to build larger parts in multiple sub-parts and then glue them together. The fabricated result shows that the VLM-ST process employing thick layers and sloped surfaces is adequate for creating the real-sized large objects in the diverse fields such as automobiles, electric home appliances, electronics. and etc.