• 인간식물환경학회지
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• 제23권6호
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• pp.615-624
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• 2020

Background and objective: Urbanization caused a reduction in urban green space and a lack of community spaces. An attempt to solve these problems, urban gardens, have become popular and are currently being implemented in various downtown areas. However, urban gardens have some inadequate aspects from a visual or landscape perspective. The goal of this study was to examine the possibility of an aesthetic and productive garden space by introducing cultivation methods through the planting system design process. Methods: The design process using plants was classified and presented to suggest the importance of the landscape and aesthetic value. An urban garden space was designed according to the perspective of 'production scenery' and 'participation aesthetics'. According to the characteristics of the plant, urban gardens were divided into vertical type (corn, millet, sorghum), climbing type (kidney bean, cucumber, bitter gourd), and runner type (melon, watermelon, peanut). After classifying plants according to the shape of the root, the structure supporting climbing was installed and the crops were cultivated in an upright form with a tunnel. Results: In the designed cultivation, each crop cooperates, without invading each other's space. Compared with the conventional cultivation, there was little difference in production, and management was made more convenient since weed outbreaks were effectively suppressed while runner type crops cover over the land's surface. Since the positions of each crop are clearly distinguished, the aesthetic value is improved by offering a sense of rhythm with a balanced design. Conclusion: The results suggest that the cultivation methods through the plant system design process have aesthetic as well as productive value, and the design using plants, an infinite living resource, could lead to an expansion of the design field. Moreover, it would enable a sustainable symbiosis between industry and environment. There is potential for the design industry to make significant progress through collaboration with agriculture, horticulture, and landscape architecture.

• 한국산학기술학회논문지
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• 제18권3호
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• pp.115-121
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• 2017

도시철도 터널 내에 축적된 미세먼지(PM10 and PM2.5)의 제거를 위해 사용되는 분진흡입차량은 에어 블로어와 흡입시스템으로 구성된 하부흡입시스템의 설계방법에 따라 성능이 달라진다. 본 논문에서는 터널 집진차량의 하부에 설치된 먼지 흡입시스템의 효율 향상을 위하여 흡입구와 에어 블로어에 코안다 효과를 이용한 유속 조절장치를 적용하여 그 효과를 확인하였다. 특히, 공기 유동에 대한 수치해석을 통하여 진공 흡입구 내에 코안다 효과를 이용한 유속조절장치를 적용하였으며, 유속 조절각이 약 90도 내외일 때 유속의 상승과 더불어 유동의 안정화가 동시에 이루어질 수 있음을 확인하였다. 또한 링 블로어에 의해 동작되는 에어 나이프형 공기 블로어는 양쪽 끝 가장자리에 코안다 효과를 유도할 수 있는 엣지 구조를 삽입함으로써 블로어 양 끝단의 유속 저하를 개선할 수 있음을 확인하였다. 이러한 4개의 통합된 모듈 형식의 흡입 시스템의 설계는 최적화를 통하여 바닥 먼지가 비산됨과 동시에 흡입구로 흡입되어 궤도면에 누적된 미세먼지와 초미세먼지의 제거에 효과적으로 활용될 수 있을 것으로 기대된다.

• Wind and Structures
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• 제35권5호
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• pp.309-322
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• 2022

Due to the complex terrain around high-speed railways, the windbreaks were established along different landforms, resulting in irregular windbreak transition regions between different subgrade infrastructures (flat ground, cutting, embankment, etc). In this paper, the effect of a windbreak transition on the wind flow around railways subjected to crosswinds was studied. Wind tunnel testing was conducted to study the wind speed change around a windbreak transition on flat ground with a uniform wind speed inflow, and the collected data were used to validate a numerical simulation based on a detached eddy simulation method. The validated numerical method was then used to investigate the effect of the windbreak transition from the flat ground to cutting (the "cutting" is a railway subgrade type formed by digging down from the original ground) for three different wind incidence angles of 90°, 75°, and 105°. The deterioration mechanism of the flow fields and the reasons behind the occurrence of the peak wind velocities were explained in detail. The results showed that for the windbreak transition on flat ground, the impact was small. For the transition from the flat ground to the cutting, the influence was relatively large. The significant increase in the wind speeds was due to the right-angle structure of the windbreak transition, which resulted in sudden changes of the wind velocity as well as the direction. In addition, the height mismatch in the transition region worsened the protective effect of a typical windbreak.

• Wind and Structures
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• 제34권3호
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• pp.275-290
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• 2022

Mobile sand barriers are a new type sand-retaining structure that can be moved and arranged according to the engineering demands of sand control. When only used for sand trapping, mobile sand barriers could be arranged in single row. For the dual purposes of sand trapping and sand stabilization, four rows of mobile sand barriers can be arranged in a staggered form. To reveal the effect of plane layout, the included angle between sand barrier direction and wind direction on the characteristics of flow fields and the sand control laws of mobile sand barriers, numerical computations and wind tunnel tests were conducted. The results showed that inflows deflected after passing through staggered arrangement sand barriers due to changes in included angle, and the sand barrier combination exerted successive wind resistance and group blocking effects. An analysis of wind resistance efficiency revealed that the effective protection length of staggered arrangement sand barriers approximately ranged from the sand barrier to 10H on the leeward side (H is sand barrier height), and that the effective protection length of single row sand barriers roughly ranged from 1H on the windward side to 20H on the leeward side. The distribution of sand deposit indicated that the sand interception increased with increasing included angle in staggered arrangement. The wind-breaking and sand-trapping effects were optimal when included angle between sand barrier direction and wind direction is 60°-90°.

• 한국지반공학회논문집
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• 제27권8호
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• pp.63-71
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• 2011

대부분 비정형 구조물인 토목분야에서 BIM(Building Information Modeling) 기법을 적용할 경우 현재 BIM 기법이 도입되기 시작한 건축분야와 비교해 상대적으로 건설 생산성 향상의 기대효과가 높을 것으로 인식되고 있다. 본 연구에서는 NATM공법 터널을 대상으로 BIM기반 3D 모벨링을 통한 물량산출을 실시하여 기존의 2D기반의 물량산출과 비교, 오차분석을 수행하였다. 그 결과 구조물공에 있어서는 오차범위가 0.00%~-1.45%로 아주 작게 나타났으나, 토공에 있어서는 오차범위가 -19.78%~35.30%로 대단히 크게 나타났다. 이를 통해 기존 2D기반 구조물공 물량산출의 경우 0.00%~5.00%의 할증률을 감안하여 본다면 BIM기반 물량산출과의 오차가 무시할 정도로 나타남에 따라 BIM기반 3D 모델링을 통한 자동 물량산출의 신뢰성을 확인하였다. 또한 토공의 경우는 토공전제의 물량산출 오차는 구조물공과 동일하게 오차가 무시할 정도이지만, 암별 물량산출 오차가 크게 나타남으로서 2D 기반 물량산출의 신뢰성에 문제가 있음을 알 수 있었다. 따라서 토공은 반드시 BIM기반 3D 모델링을 통한 물량산출을 수행하여 물량산출의 신뢰성을 확보해야하는 사항이라 판단되며, BIM의 설계, 시공, 유지관리 단계의 정보통합의 장점을 고려하여 토목분야에서의 BIM 설계기법 도입에 대한 효용성 및 적용 가능성을 확인하였다.

• 터널과지하공간
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• 제17권4호
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• pp.255-265
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• 2007

폐광지역의 침하발생 메커니즘 및 영향범위는 현장의 지반조건, 지압분포, 채굴적의 기하학적인 조건, 상부 구조물의 하중 조건 등에 따라 달라지므로 이를 예측하기는 매우 어렵다. 또한 지질 및 지반 상태, 탄층의 발달 상태, 채굴방법 등이 채굴현장마다 다르므로 기존의 보강대책을 그대로 적용하는 데에는 한계가 있다. 본 연구에서는 국내 폐광지역에 대한 합리적인 보강대책 수립을 위해 광역 채굴현황조사를 바탕으로 채굴적의 분포를 파악하고, 대심도 시추조사, 탄성파 토모그래피, 시추공 영상촬영 등의 상세 지반조사를 수행하여 석탄층의 분포현황과 암반이완상태를 파악하였다. 이를 토대로 지반침하이론에 의해 침하발생 유형을 예측하고 지반침하량을 산정하였다. 또한, 연구대상 지역의 침하발생 메커니즘을 분석하였으며, 기존 폐광지역 보강사례를 분석하여 각 침하원인별로 대상지역의 지반특성에 부합되는 지반 및 구조물기초에 대한 보강대책을 수립하였다.

• 대한기계학회논문집B
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• 제25권12호
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• pp.1821-1830
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• 2001

The flow around free end of a finite circular cylinder (FC) embedded in an atmospheric boundary layer has been investigated experimentally. The experiments were carried out in a closed-return type subsonic wind tunnel with varying aspect ratio of the finite cylinder mounted vertically on a flat plate. The wakes behind a 2-D cylinder and a finite cylinder located in a uniform flow were measured for comparison. Reynolds number based on the cylinder diameter was about Re=20,000. A hot-wire anemometer was employed to measure the wake velocity and the mean pressure distributions on the cylinder surface were also measured. The flow past the FC free end shows a complicated three-dimensional wake structure and flow phenomenon is quite different from that of 2-D cylinder. The three-dimensional flow structure was attributed to the downwashing counter rotating vortices separated from the FC free end. As the FC aspect ratio decreases, the vortex shedding frequency decreases and the vortex formation length increases compared to that of 2-D cylinder. Due to the descending counter-rotating twin-vortex, near the FC free end, regular vortex shedding from the cylinder is suppressed and the vortex formation region is hardly distinguished. Around the center of the wake, the mean velocity for the FC located in atmospheric boundary layer has large velocity deficit compared to that of uniform flow.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.35-38
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• 2002

In this paper, the characteristics of channel hot electron (CHE) injection for the write operation in a NOR-type SONOS flash memory with common source line were investigated. The thicknesses of he tunnel oxide, the memory nitride， and the blocking oxide layers for the gate insulator of the fabricated SONOS devices were $34{\AA}$, $73{\AA}$, and $34{\AA}$, respectively. The SONOS devices compared to floating gate devices have many advantages, which are a simpler cell structure, compatibility with conventional logic CMOS process and a superior scalability. For these reasons, the introduction of SONOS device has stimulated. In the conventional SONOS devices, Modified Folwer-Nordheim (MFN) tunneling and CHE injection for writing require high voltages, which are typically in the range of 9 V to 15 V. However CHE injection in our devices was achieved with the single power supply of 5 V. To demonstrate CHE injection, substrate current (Isub) and one-shot programming curve were investigated. The memory window of about 3.2 V and the write speed of $100{\mu}s$ were obtained. Also, the disturbance and drain turn-on leakage during CHE injection were not affected in the SONOS array. These results show that CHE injection can be achieved with a low voltage and single power supply, and applied for the high speed program of the SONOS memory devices.

• 대한화학회지
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• 제38권6호
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• pp.435-441
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• 1994

3차원 금속 착제, Cd(pn)Ni(CN)4를 host로 하는 포접 화합물을 합성하고, X-선 회절 데이타를 이용한 단결정의 구조해석을 하였다. 결정학적 데이타는 다음과 같다. $[Cd(pn)Ni(CN)_4]{\cdot}0.5(CH_3COCH_3{\cdot}H_2O)$, Fw = 387.35, Orthorhombic, $Pn2_1a$, a = 13.950(3) $\AA$, b = 26.713(7) $\AA$, c = 7.628(1) $\AA$, V = 2843(1) $\AA^3$, Z = 4, $D_x=1.81 gcm^{-3}$, $\mu(MoK{\alpha})$ = $28.153cm^{-1}$, T = 297K, 3521개($F_0>3{\sigma}(F_0)$)의 회절 강도에 대한 최종 신뢰도 인자 R = 0.0418이 얻어졌다. 이 포접 화합물은 thiourea 포접 화합물과 유사한 턴넬형의 포접 공간(T-type)을 형성하며, 이런 포접공간 내에 분자당 0.5개의 아세톤과 물분자를 guest로서 받아 들인다. 표제의 포접 화합물은 이미 보고된 바와 같이, 가지달린 유기 guest분자가 host의 기하구조를 T-type으로 이끈다고 하는 host 선택성에 대한 또 하나의 증거가 된다.

• Wind and Structures
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• 제19권3호
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• pp.233-247
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• 2014

Vortex-induced oscillation is a type of aeroelastic phenomenon, to which extended structures such as long-span bridges are most susceptible. The vortex-induced vibration (VIV) behaviors of a concerned bridge were investigated conventionally in virtue of wind tunnel tests on string-mounted sectional models. This necessitates the building of a linkage between the response of the sectional model and that of the prototype structure. Although many released literatures have related to this issue and provided suggestions, there is a lack of consistency among them. In this study, some theoretical models describing the vortex-induced structural motion, including the linear empirical model, the nonlinear empirical model and the modified (or generalized) nonlinear empirical model, are firstly reviewed. Then, the concept of equivalent mass density is introduced based on the principle that an equal input of energy should result in identical structural amplitudes. Based on these, the theoretical linkages between the amplitude of a section model and that corresponding to the prototype bridge are discussed with different analytical models. Theoretical derivation indicates that such connections are dependent mainly on two factors, one is the presupposed shape of deformation, and the other is the theoretical VIV model employed. The theoretical analysis in this study shows that, in comparison to the nonlinear empirical models, the linear one can result in obvious larger estimations of the full bridges' responses, especially in cases of cable-stayed bridges.