• 센서학회지
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• 제30권4호
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• pp.229-235
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• 2021

This study presents a simple approach for the assembly of a free-standing conductive electronic nanofilm of single-walled carbon nanotubes (SWNTs) suitable for enzymatic electrochemical biosensors. A large-scale SWNT electronic film was successfully produced by the dialysis of p-Terphenyl-4,4''-dithiol (TPDT)-treated SWNTs. Furthermore, Horseradish peroxidase (HRP) was immobilized on the TPDT-SWNT electronic film, and the enzymatic detection of hydrogen peroxide (H₂O₂) was demonstrated without mediators. The detection of H₂O₂ in the negative potential range (-0.4 V vs. Ag/AgCl) was achieved by direct electron transfer of heme-based enzymes that were immobilized on the TPDT-SWNT electronic film. The SWNT-based biosensor exhibited a wide detection range of H₂O₂ from 10 µM to 10 mM. The HRP-doped SWNT electronic film achieved a high sensitivity of 342 ㎛A/mM·cm² and excellent selectivity against a variety of redox-active interfering substances, such as ascorbic acid, uric acid, and acetaminophen.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.96-96
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• 2016

Nanotechnology mostly employs nano-materials and nano-structures with distinctive properties based on their size, structure, and composition. It is quite difficult to produce nano-materials and nano-structures with identical sizes, structures, and compositions in large quantities, because of spatiotemporal fluctuation of production processes. In other words, fluctuation is the bottleneck in nanotechnology. We propose three strategies to suppress such fluctuations: employing 1) difference between linear and nonlinear phenomena, 2) difference in time constants, and 3) nucleation as a bottleneck phenomenon. We are also developing nano- and micro-scale guided assembly using plasmas as a plasma nanofabrication.1-5) We manipulate nano- and micro-objects using electrostatic, electromagnetic, ion drag, neutral drag, and optical forces. The accuracy of positioning the objects depends on fluctuation of position and energy of an object in plasmas. Here we evaluate such fluctuations and discuss the mechanism behind them. We conducted in-situ evaluation of local plasma potential fluctuation using tracking analysis of fine particles (=objects) in plasmas. Experiments were carried out with a radio frequency low-pressure plasma reactor, where we set two quartz windows at the top and bottom of the reactor. Ar plasmas were generated at 200 Pa by applying 13.56MHz, 450V peak-to-peak voltage. The injected fine particles were monodisperse methyl methacrylate-polymer spheres of $10{\mu}m$ in diameter. Fine particles were injected into the reactor and were suspended around the plasma/sheath boundary near the powered electrode. We observed binary collision of fine particles with a high-speed camera. The frame rate was 1000-10000 fps. Time evolution of their distance from the center of mass was measured by tracking analysis of the two particles. Kinetic energy during the collision was obtained from the result. Potential energy formed between the two particles was deduced by assuming the potential energy plus the kinetic energy is constant. The interaction potential is fluctuated during the collision. Maximum amplitude of the fluctuation is 25eV, and the average is 8eV. The fluctuation can be caused by neutral molecule collisions, ion collisions, and fluctuation of electrostatic force. Among theses possible causes, fluctuation of electrostatic force may be main one, because the fine particle has a large negative charge of -17000e and the corresponding electrostatic force is large compared to other forces.

• 환경영향평가
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• 제21권3호
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• pp.381-389
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• 2012

This study was conducted to analyze the weight factors for siting the electric facilities using Analytic Heirarchy Process technique participating the stakeholders. Siting the electric facilities has been a dispute of long standing because of landscape damage, geological deformation and various environmental problems such as electromagnetic effect to human health. For analyzing the weight factors by AHP technique, the questionnaire process was applied to the fifteen committee members including representatives of resident, academic experts, members of local assembly, officers of local government, journalists, etc. in Gangwondo, Korea. Weight factors for siting the electric facilities by AHP committee members resulted in residential areas 35.06%, cultural assets 16.68%, landscape conservation 13.11%, large-scale ecological corridor 10.17%, connectability of electric transmission line 8.32% respectively. The distance from residential areas was the most important factor preferred by committee members for siting the electric facilities.

• Progress in Superconductivity
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• 제8권1호
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• pp.122-126
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• 2006

This paper presents experimental and numerical investigation on heat generation of a bulk HTS for application to a 100 kWh Superconductor Flywheel Energy Storage System(SFES) bearing. An experimental device is manufactured to reproduce varying magnetic field conditions that a bulk HTS may experience during the operation of the 100 kWh SFES. The bulk HTS is directly cooled by a cryocooler while the heat is generated by the eddy currents created by varying magnetic fields induced by a coil. In order to design the cryocooling system for the 100 kWh SFES project, a preliminary experiment to investigate the actual cooling load variation under AC magnetic field has been carried out. In the experiment, two different copper holders were designed and tested. Several temperature sensors were installed on each component of the assembly and the temperatures were measured for several operating conditions of the 100 kWh SFES. The experimental investigation on the thermal response of the bulk HTS and its holder is considered to be a valuable step fur the successful materialization of a large-scale SFES.

• International Journal of Precision Engineering and Manufacturing
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• 제8권3호
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• pp.64-70
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• 2007

Of all the rapid tooling (RT) methods currently available, thick-layer laminated tooling is the most suitable for large-scale, low-cost dies and molds. Currently, the determination of a lamina's contour or profile and the associated slicing algorithms are based on existing rapid prototyping (RP) data manipulation technology. This paper presents a new adaptive slicing algorithm developed exclusively for profiled edge laminae (PEL) tooling PEL tooling is a thick-layer RT technique that involves the assembly of an array of laminae, whose top edges are simultaneously profiled and beveled using a line-of-sight cutting method based on a CAD model of the intended tool surface. The cutting profiles are based on the intersection curve obtained directly from the CAD model to ensure geometrical accuracy. The slicing algorithm determines the lamina thicknesses that minimize the dimensional error using a new tool shape error index. At the same time, the algorithm considers the available lamination thicknesses and desired lamina interface locations. We demonstrate the new slicing algorithm by developing a simple industrial PEL tool based on a CAD part shape.

• 한국기계가공학회지
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• 제9권5호
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• pp.76-82
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• 2010

In this study, we carried out to evaluate the shock-proof of a large scale motor for the naval vessel using dynamic design analysis method (DDAM) and full transient dynamic analysis. Analytical models for main assemblies (motor frame, rotor and stator assembly) were consisted of the tetrahedral solid elements and the equipments which installed in the upper side of the motor were substituted the mass elements. And we also modelled resilient mounts of a motor using the beam elements with appropriate directional stiffness. The DDAM was conducted according to NRL memorandum report 1396 and the full transient dynamic analysis was performed applying directional triple half triangle shock wave to the motor using ANSYS 12. As a result, we could compare of the results according to each analytic method and find the motor to satisfy the design criteria of the maximum stress and deformation.

• 수산경영론집
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• 제51권1호
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• pp.1-17
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• 2020

This study is an analysis of the Aquaculture Industry Development Act that has recently been passed by the National Assembly. In order to improve the structural problem of Korea's aquaculture, a large revision of aquaculture related laws and regulations is needed. The enactment of Aquaculture Industry Development Act is necessary to that effect. It is adequate to aim for development as aquaculture industry not as aquaculture, to alleviate entry restriction of aquaculture, and to provision diverse promotion and support policies. However, it is a concern whether the current Aquaculture Industry Development Act can achieve its goal of enhancing the competitiveness of aquaculture and sustainability. Rather than to solve the problem, the act holds the possibility of further fixing or exacerbating the problem. So there is concern for side-effects after the enactment. This is due to the fact that it complicates terminologies by unnecessarily differentiating aquaculture related concepts from the existing Fisheries Act, lacks regulations regarding voluntary participation in aquaculture, and has limited methods to alleviate entry restriction. In addition, there are very few measures for the scale improvement of aquaculture along with the unlikeliness of a significant effect of the review and evaluation for re-licensing. Thus, the Aquaculture Industry Development Act should promptly be revised after its enactment.

• 한국도로학회논문집
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• 제12권2호
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• pp.129-136
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• 2010

현행 주차장법상의 부설주차장 설치기준은 위락시설, 문화 및 집회시설, 단독주택, 공장 등 설치 대상 시설물을 9개 그룹으로 분류하고, 그룹 내 시설물에 대해서는 동일한 설치기준이 제시되어 있다. 지자체는 필요에 따라서 지자체 조례로 시설물의 종류를 세분하거나 설치기준의 2분의 1의 범위(${\pm}$50%) 안에서 이를 강화 또는 완화할 수 있도록 되어 있다. 최근 건축물의 종류가 다양해지고 기능이 혼재되어 같은 그룹에 속하더라도 시설물에 따라 주차장설치기준을 세분화할 필요가 있으나, 대부분 지자체의 경우 체계적이고 일관된 기준 없이 주차장법에서 제시된 시설분류기준에 강화된 획일적인 설치기준을 조례에 적용하고 있다. 특히, 산업단지 내 위치한 대규모 첨단제조시설의 경우 공정이 자동화되어 건물규모대비 근무인력이 소수임에도 불구하고 이에 대한 별도의 세부적인 구분없이 기타시설 또는 공장시설로 분류되어 일반 제조공장과 동일한 일괄적 기준을 적용하고 있다. 따라서 본 연구에서는 현장조사를 통해 산업단지 내 공장시설에 대한 기존 주차원단위 산정에 대한 문제점을 분석하고, 이를 해결하기 위해 방안으로 용도 및 규모특성을 고려한 부설주차장 설치기준 개선방안을 제시하였다.

• 국제학술발표논문집
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• The 8th International Conference on Construction Engineering and Project Management
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• pp.75-84
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• 2020

Modular construction is a construction method whereby prefabricated volumetric units are produced in a factory and are installed on site to form a building block. The construction productivity can be substantially improved by the manufacturing and assembly of standardized modular units. 3D printing is a computer-controlled fabrication method first adopted in the manufacturing industry and was utilized for the automated construction of small-scale houses in recent years. Implementing 3D printing in the fabrication of modular units brings huge benefits to modular construction, including increased customization, lower material waste, and reduced labor work. Such implementation also benefits the large-scale and wider adoption of 3D printing in engineering practice. However, a critical issue for 3D printed modules is the loading capacity, particularly in response to horizontal forces like wind load, which requires a deeper understanding of the building structure behavior and the design of load-bearing modules. Therefore, this paper presents the state-of-the-art literature concerning recent achievement in 3D printing for buildings, followed by discussion on the opportunities and challenges for examining 3D printing in modular construction. Promising 3D printing techniques are critically reviewed and discussed with regard to their advantages and limitations in construction. The appropriate structural form needs to be determined at the design stage, taking into consideration the overall building structural behavior, site environmental conditions (e.g., wind), and load-carrying capacity of the 3D printed modules. Detailed finite element modelling of the entire modular buildings needs to be conducted to verify the structural performance, considering the code-stipulated lateral drift, strength criteria, and other design requirements. Moreover, integration of building information modelling (BIM) method is beneficial for generating the material and geometric details of the 3D printed modules, which can then be utilized for the fabrication.

• 한국전산구조공학회논문집
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• 제30권4호
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• pp.329-334
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• 2017

다양한 산업 분야의 구조물은 여러 부구조의 조합으로 구성되며, 시스템의 자유도 또한 무수히 많다. 높은 복잡성을 가지는 구조물의 해석 및 계산 효율을 향상시키기 위해서 해석 모델의 단순화 및 자유도 축소가 요구된다. 지난 50여 년 동안 규모가 큰 공학적 문제를 단순화하기 위해 다양한 부분구조화 기법들이 개발되어 왔다. 이러한 부분구조화 기법들은 Newton-Raphson 알고리즘 등과 같은 반복계산을 동반하는 비선형 구조해석 문제 해석에 매우 효과적이다. 본 논문에서는 기 개발된 비선형 부분구조화 기법 중의 하나인 모드미분(modal derivatives)을 이용하여 기하비선형 보의 모델 축소에 적용하고자 한다. 모드미분은 모드 기반 축소 기저의 2차항의 형태로, 선형모드의 조합으로 근사 가능한 변위벡터를 미소변위에 대한 Taylor 급수를 통해 확인할 수 있으며, 시스템의 고유치 문제를 모드 좌표로 미분을 함으로써 얻어진다. 모드미분에는 비선형 접선 강성행렬의 미분을 포함하고 있으며, 이는 유한차분법 등의 근사를 통해 계산할 수 있다. 제안된 방법론은 기하학적 비선형 문제에 우수한 성능을 보이는 동시회전 유한요소법에 적용하였다. 수치예제를 통해 보의 경계가 수평으로 움직일 수 있는 문제에서는 기존의 모드축소기법이 매우 비효율적임을 알 수 있었다. 한편 모드미분을 이용한 축소기법은 다양한 경계조건에 대하여 우수한 성능을 보임을 확인하였다.