• 농촌계획
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• 제24권1호
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• pp.99-111
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• 2018

This study was conducted for the purpose of deriving implications by observing the changing patterns and characteristics of the farmland reduction area in urban vicinity with Gimhae city, Gyeongsangnam-do as the subject. In order to achieve this goal, we first examined the problems and possibilities of farmland reduction area in urban vicinity through a theoretical review. Additionally, the characteristics of land use and community were examined for Gimhae city, Gyeongsangnam-do. The results of the study are summarized as follows. First, for 35 years from 1981 to 2015, Gimhae decreased $50.52km^2$ of farmland, which is about 17.4 times that of Yoido, and about 69.4% of the decreased farmland area. Second, the decrease in agricultural land has been expanding to the whole of Gimhae City from 1990 to 2010, and has been continuing since 2010 around dong-area. Third, in the farmland reduction area in urban vicinity, the number of settlements increases rapidly, but the aging population also increases. Fourth, the composition of the community is getting complicated with the change of the members. Taken together, it is necessary to manage the area efficiently because rapid change is present in the farmland reduction area in urban vicinity. Based on this, the implications are summarized as follows. First, there is a change in land use due to the reduction of farmland not designated as agricultural development region. Therefore, it is necessary to supplement the farmland-conversion standard. Second, despite the fact that land use management has been carried out, there have been problems such as uncontrolled development due to the development pressure beyond institutional management, and therefore it is necessary to improve the structural defects of the pertinent legal system. Fourth, while the traditional farming activities are decreasing with the decrease of agricultural land area, the increase in farms with secondary jobs and the urban-rural interchanges organization's efforts can lead to increased visits from outsiders that seek rural tourism and experiential learning.

• 한국환경복원기술학회지
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• 제9권6호
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• pp.107-116
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• 2006

Recently, it has been important not only to evaluate environmental effects but also to assess cumulative and comprehensive effects by the development projects. This paper concentrates on temporal and spatial cumulative impacts on Suji district in Yongin, Gyunggi-do. This paper adopted two methods to assess the cumulative impacts. First, it assesses the temporal change of forest patch size and land cover according to the patch size. Second, it compares housing development zones with the neighborhood. The result of the research appears that the damage is very serious, especially in small forest. The Forest area is changed to farm land, most of them become to built-up area later. In addition, it is assessed that the secondary housing development projects did more harm than the initial one. By assessing the cumulative impacts on Suji district, this research suggests to minimize two kinds of solutions : comprehensive environmental assessments in regional unit and regulation on total forest quantity.

• 대한건축학회논문집:계획계
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• 제35권4호
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• pp.45-52
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• 2019

The most ordinary form of residential type in Korea is a plate-type apartment, and the common space in these apartment is attracting as an important factor for enhancing social exchanges among neighbors and forming community consciousness. In addition, it provides a sense of psychological security by enabling natural exchanges and communication in contemporary society. It is desirable to plan the flow of space in such a way that private, semi-private, semi-public, and public spaces are linked. Semi-private and semi-public spaces can be defined as common spaces. Semi-private spaces are strongly recognized in the order of unit household entrance, main entrance, elevator, corridor, staircase, playground, bench, trail, walkway and parking lot, exercise space, main/back gate, the ability to gratify is increased sense of belonging, ownership consciousness formation, defensive function. Semi-public space is strongly recognized in the order of playground, bench, exercise space, trail, main entrance, walkway and parking lot, unit household entrance, main/back gate, corridor, staircase, elevator, the ability to gratify is increase of social contact, Secondary activity space function. In addition, the function to gratify in the common space differs according to gender and age group among resident characteristics, and differs according to corridor type, parking lot type and main entrance type. Therefore, differentiated planning of common space is needed in consideration of these differences in the design of common space in future.

• Geomechanics and Engineering
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• 제28권2호
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• pp.171-180
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• 2022

Time-dependent stress-strain behaviour significantly influences the compressibility characteristics of the clayey soil. In this paper, a series of oedometer tests were conducted in two loading patterns and investigated the time-dependent compressibility characteristics of Indian Montmorillonite Clay, also known as black cotton soil (BC) soil, during loading-unloading stages. The experimental data are analyzed using a new non-linear function of the Elasto-Visco-Plastic Model considering Swelling behaviour (EVPS model). From the experimental result, it is found that BC soil exhibits significant time-dependent behaviour during creep compared to the swelling stage. Pore water entrance restriction due to consolidated overburden pressure and decrease in cation hydrations are responsible factors. Apart from it, particle sliding is also evident during creep. The time-dependent parameters like strain limit, creep coefficient and C_αe/C_c are observed to be significant during the loading stage than the swelling stage. The relationship between creep coefficients and applied stresses is found to be nonlinear. The creep coefficient increases significantly up to 630 kPa-760 kPa (during reloading), and beyond it, the creep coefficient decreases continuously. Several parameters like loading duration, the magnitude of applied stress, loading history, and loading path have also influenced secondary compressibility characteristics. The time-dependent compressibility characteristics of BC soil are presented and discussed in detail.

• Structural Engineering and Mechanics
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• 제52권6호
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• pp.1069-1084
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• 2014

The long-term performance of plates resting on viscoelastic foundations is a major concern in the analysis of soil-structure interaction. As a powerful mathematical tool, fractional calculus may address these plate-on-foundation problems. In this paper, a fractionalized Zener model is proposed to study the time-dependent behavior of a uniformly loaded rectangular thin foundation plate. By use of the viscoelastic-elastic correspondence principle and the Laplace transforms, the analytical solutions were obtained in terms of the Mittag-Leffler function. Through the analysis of a numerical example, the calculated plate deflection, bending moment and foundation reaction were compared to those from ideal elastic and standard viscoelastic models. It is found that the upper and lower bound solutions of the plate response estimated by the proposed model can be determined using the elastic model. Based on a parametric study, the impacts of model parameters on the long-term performance of a foundation plate were systematically investigated. The results show that the two spring stiffnesses govern the upper and lower bound solutions of the plate response. By varying the values of the fractional differential order and the coefficient of viscosity, the time-dependent behavior of a foundation plate can be accurately captured. The fractional differential order seems to be dependent on the mechanical properties of the ground soil. A sandy foundation will have a small fractional differential order while in order to simulate the creeping of clay foundation, a larger fractional differential order value is needed. The fractionalized Zener model is capable of accounting for the primary and secondary consolidation processes of the foundation soil and can be used to predict the plate performance over many decades of time.

• Steel and Composite Structures
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• 제35권4호
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• pp.475-494
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• 2020

Presented are experimental results from 24 full-scale push test specimens to study the behaviour of composite beams with trapezoidal profiled sheeting laid transverse to the beam axis. The tests use a single-sided horizontal push test setup and are divided into two series. First series contained shear loading only and the second had normal load besides shear load. Four parameters are studied: the effect of wire mesh position and number of its layers, placing a reinforcing bar at the bottom flange of the deck, normal load and its position, and shear stud layout. The results indicate that positioning mesh on top of the deck flange or 30 mm from top of the concrete slab does not affect the stud's strength and ductility. Thus, existing industry practice of locating the mesh at a nominal cover from top of the concrete slab and Eurocode 4 requirement of placing mesh 30 mm below the stud's head are both acceptable. Double mesh layer resulted in 17% increase in stud strength for push tests with single stud per rib. Placing a T16 bar at the bottom of the deck rib did not affect shear stud behaviour. The normal load resulted in 40% and 23% increase in stud strength for single and double studs per rib. Use of studs only in the middle three ribs out of five increased the strength by 23% compared to the layout with studs in first four ribs. Eurocode 4 and Johnson and Yuan equations predicted well the stud strength for single stud/rib tests without normal load, with estimations within 10% of the characteristic experimental load. These equations highly under-estimated the stud capacity, by about 40-50%, for tests with normal load. AISC 360-16 generally over-estimated the stud capacity, except for single stud/rib push tests with normal load. Nellinger equations precisely predicted the stud resistance for push tests with normal load, with ratio of experimental over predicted load as 0.99 and coefficient of variation of about 8%. But, Nellinger method over-estimated the stud capacity by about 20% in push tests with single studs without normal load.

• Journal of Electrochemical Science and Technology
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• 제12권4호
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• pp.458-464
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• 2021

Lithium ion batteries (LIBs) is a kind of rechargeable secondary battery, developed from lithium battery, lithium ions move between the positive and negative electrodes to realize the charging and discharging of external circuits. Zeolitic imidazolate frameworks (ZIFs) are porous crystalline materials in which organic imidazole esters are cross-linked to transition metals to form a framework structure. In this article, ZIF-67 is used as a sacrificial template to prepare nano porous carbon (NPC) coated cobalt nanoparticles. The final product Co/NPC composites with complete structure, regular morphology and uniform size were obtained by this method. The conductive network of cobalt and nitrogen doped carbon can shorten the lithium ion transport path and present high conductivity. In addition, amorphous carbon has more pores that can be fully in contact with the electrolyte during charging and discharging. At the same time, it also reduces the volume expansion during the cycle and slows down the rate of capacity attenuation caused by structure collapse. Co/NPC composites first discharge specific capacity up to 3115 mA h/g, under the current density of 200 mA/g, circular 200 reversible capacity as high as 751.1 mA h/g, and the excellent rate and resistance performance. The experimental results show that the Co/NPC composite material improves the electrical conductivity and electrochemical properties of the electrode. The cobalt based ZIF-67 as the precursor has opened the way for the design of highly performance electrodes for energy storage and electrochemical catalysis.

• 한국산학기술학회논문지
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• 제18권10호
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• pp.745-755
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• 2017

대학 캠퍼스는 시대적 흐름과 학생들의 생활패턴 변화 등의 다양한 공간 계획적 이슈를 충족시키고자 노력해야 한다. 물리적 공간의 지속적인 변화는 대학의 경쟁력 확보에도 상당한 영향을 미칠 수 있으며, 주된 구성원인 학생들의 만족도에 영향을 미치기에 중요한 요소라고 할 수 있다. 현재 학생들의 학습 방법은 기존의 개별 학습 형태를 벗어나 여러 명이 모여 토론하는 그룹형 학습으로 변화하고 있다. 또한 멀티미디어 시설 및 기술을 활용하여 다양한 자료를 재가공해야하는 새로운 유형의 과제가 등장하고 있어 관련된 설비 또한 새롭게 구축해야 하는 상황에 놓여있다. 이러한 다각적인 변화를 수용하기 위해 새로운 유형의 독립된 공간이 각 대학에 등장하고 있는데, 이를 그룹스터디룸이라고 한다. 본 연구에서는 K대학 내 조성된 그룹스터디룸들이 가지는 공간적 특성을 분석하고자 하였다. 또한 공간 계획요소가 실제 사용자들의 만족도와 어떠한 관련이 있는지 IPA분석을 통해 확인하고자 하였다. 이를 통하여 향후 새롭게 구축해야 하는 대학 내 시설들에 대한 건축적 이슈를 도출하여 각 대학별로 활용 가능한 디자인 요소들을 소개하고자 하였다.

• 한국환경생태학회지
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• 제32권1호
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• pp.77-96
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• 2018

난온대 상록활엽수림의 식생천이계열을 논의하기 위해 극상림이라 알려진 육박나무군락이 생육하는 한국 3곳(비진도, 애도, 보길도)과 일본 1곳(다치바나산)을 조사 및 분석했다. 이를 토대로 한국, 일본, 중국, 대만의 관련문헌을 검토해 상록활엽수림의 분포특성, 식생천이계열 및 극상수종을 고찰했다. 다치바나산과 애도는 육박나무군락이 가장 발달한 식생구조를 보였지만, 토양분석 및 CCA분석에서 육박나무군락을 난온대 천이극상단계의 조건으로 판단하기엔 부족함이 보였다. 한국과 일본에서 육박나무군락은 드물게 분포하는 반면, 동아시아 난온대 지역에 보편적인 식생유형은 후박나무류, 잣밤나무류, 가시나무류였다. 한국 난온대 지역의 식생천이계열은 곰솔 소나무 졸참나무 등(초기단계)${\rightarrow}$후박나무 생달나무 참식나무 육박나무 등(중간단계)${\rightarrow}$구실잣밤나무 붉가시나무 참가시나무 등(극상단계)의 순으로 2차천이가 진행될 것으로 추정된다. 단, 조풍의 영향을 강하게 받는 입지조건이나 잣밤나무류 가시나무류의 종자공급이 어려운 곳에서는 후박나무류 유형이 토지극상일 것이다.

• 전자공학회논문지S
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• 제36S권1호
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• pp.29-37
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• 1999

일반적으로 신경망의 정보처리 능력은 신경망의 구조와 효율적인 학습패턴에 의해 결정된다. 그러나 아직까지 체계적으로 신경망의 구조를 설계하거나 효율적인 학습패턴을 선택하는 방법은 없다. 한편 진화 알고리즘은 개체군을 이용한 탐색법으로 전역적 최적해를 구하는 데 많이 사용되고 있으며, 특히 최적의 시스템을 설계하고자 할 때 매우 유용한 방법이다. 본 논문에서는 유전자 알고리즘으로 구성된 두 개의 개체군이 서로 경쟁적으로 진화하는 공진화 방법에 의해 최적의 신경망구조를 찾는 방법을 제안한다. 이 방법은 신경망구조를 나타내는 주개체군과 학습패턴을 나타내는 부개체군으로 되어 있으며, 이 두 개체군(신경망과 학습패턴)은 서로 경쟁적으로 진화한다. 즉, 학습패턴은 신경망이 학습하기 힘든 패턴으로 진화하고 신경망은 그 패넌들을 학습할 수 있도록 진화하단. 이 방법은 부적절한 학습패턴의 선택과 임의적인 신경망의 설계로 인한 시스템의 성능이 저하되는 것을 해결한다. 또한 공진화 방법에서 각 개체군의 적합도는 동적으로 변화하기 때문에 그 진행과정을 쉽게 알 수 없다. 따라서 본 논문에서는 그 진행과정을 관찰할 수 있는 방법도 소개한다. 마지막으로 제안한 방법을 로봇 매니플레이터의 비주얼 서보임 문제에 적용하여 그 유효성을 검증한다.