• Korean Journal of Environment and Ecology
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• v.22 no.1
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• pp.1-10
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• 2008

The Bulyeongsa Valley in Uljin-gun(Gyeungbuk) has a unique beautiful landscape and plentiful ecosystem, and Pinus densiflora for. erecta is distributed widely. Recently as the widening of national road in Bulyeongsa Valley, comprehensive survey is needed. So to investigate the forest distribution and structure, ninety-nine plots were installed and surveyed. Each plot size is $100m^2$. Important percentage analysis of the summarize results, vegatation of Bulyeung valley is found out that dominant species is Pinus densiflora mainly and Quercus variabilis and Quercus serrata are compatitive relation with Pinus densiflora partially. The analysis results of the actual vegetation and degree of green naturality(DGN) showed that Pinus densiflora community is 47.75%, and DGN 8 is 69.14% in total. From the above results, vegatation of Bulyeungsa valley is found out that dominant species is Pinus densiflora mainly, and Quercus variabilis and Quercus serrata are competitive relation with Pinus densiflora partially.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.515-520
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• 2020

CMOS used in digital circuit design technology has reached the limit of integration due to quantum tunneling. Quantum-dot cellular automata (QCA), which can replace this, has many advantages such as low power consumption and fast switching speed, so many digital circuits of CMOS have been proposed based on QCA. Among them, the multiplexer is a basic circuit used in various circuits such as D-flip-flops and resistors, and has been studied a lot. However, the existing multiplexer has a disadvantage that space efficiency is not good. Therefore, in this paper, we propose a new multilayered multiplexer using cell interaction and D-latch using it. The multiplexer and D-latch proposed in this paper have improved area, cell count, and delay time, and have excellent connectivity and scalability when designing large circuits. All proposed structures are simulated using QCADesigner to verify operation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.1
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• pp.127-136
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• 2008

In these days, frequency of constructions on e freeway are increasing according as growing of the importance of e road maintenance and the road management. Work zone on the freeway where vehicles pass with high speed needs control method of lane closure and construction equipment. Because there are seldom researches in domestic study about reflecting characteristics of domestic road, sometimes we have applied for foreign cases to our traffic circumstance but it is not proper to apply for standard of other countries in our cases. foreign nation has different country square, condition of road, and level of people mind. Therefore, this study shows traffic accident characteristics in freeway work zones in Korea. At first, this study collected traffic accident data which include for 3 years $2003{\sim}2005$ in the whole freeway in Korea and then divided the data to five parts - level of the accident, type of the construction work, type of the accident, reason of the accident, according to geometric. According to comparing with non-work zones accident, this study found traffic accident characteristics in freeway work zones in Korea and suggested some alternative ideas for safety of work zones.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.681-688
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• 2000

In this paper, a planar antenna that is small and light, is designed and analyzed aiming handset antenna of IMT-2000. Employing the Ensemble simulator based on a MoM, design-parameters are found to determine a resonant frequency. Therefore, it is analyzed with the Ensemble simulation and FDTD numerical for resonating at the allocated frequency for IMT-2000 in the fixed antenna dimension of 21$^{\circ}$wing angle that is a design parameter. Analyzing with FDTD method, Though the results of FDTD are very exact, this analysis introduces errors due to the staircasing approximation in the slope of bowtie. To reduce this error, it is divided to 4-ranges where the cell contains the boundary of perfect conductor/free space. Then, each range is calculated by different by different equation, which modify the H-field to add the component of the area and length of the cell filled with free space. Therefore, the modified FDTD algorithm provided with a narrow bandwidth of return loss calculated with a standard FDTD algorithm that can be extended to the desired ranges.

• The KIPS Transactions:PartD
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• v.9D no.1
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• pp.43-56
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• 2002

Most of works have been performed on representation of spatiotemporal objects from various points of view. Most of them represent spatiotemporal objects using approaches from GIS, temporal databases, object-oriented databases or data type. Spatiotemporal objects can be classified as objects whose position and shape changes discretely over time, objects whose position changes continuously and objects whose shape changes continuously as well as position. Previous works on spatiotemporal model have focused on only one of them. In this paper, we propose a spatiotemporal model that can represent three types of objects in Euclidean plan. For this purpose, we represent both discrete and continuous moving objects by defining temporal model extended from valid time and by defining relationship between two consecutive versions of objects. The proposed spatiotemporal object model is based on open GIS specification so that it has compatibility with existing spatial data model.

• The Journal of the Acoustical Society of Korea
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• v.36 no.1
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• pp.12-22
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• 2017

It is important to predict accurately reverberation level, which is a limiting factor in underwater target detection. Recently, the studies have been expanded from monostatic sonar to bistatic sonar in which source and receivers are separated. To simulate the bistatic reverberation level, the computation processes for propagation, scattering strength, and scattering cross section are different from those in monostatic case and more complex computation processes are required. Although there have been many researches for bistatic reverberation, few studies have assessed the bistatic scattering cross section which is a key factor in simulate reverberation level. In this paper, a new method to estimate the bistatic scattering cross section is suggested, which uses the area of intersection between two circles. Finally, the reverberation levels simulated with the scattering cross section estimated using the method suggested in this paper are compared with those estimated using the methods previously suggested and those measured from an acoustic measurements conducted in May 2013.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.5
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• pp.138-150
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• 2009

10 years ago, Korea proclaimed the bike traffic activation law. Many cities have constructed bike paths and parking lots. However, because of increased bike users, lack of bike paths, and parking lots, it is predisposed to avoidance to ride. This study suggests reasonable bike parking lots scale and estimated bike parking lots using the bike traffic assignments. As results, reasonable bike parking lots scale is approximately 5% of car parking lots, which is minimum value. Then, each city can estimate reasonable bike parking lots scale by considering the characteristics and size of cities.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.975-975
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• 2012

최근까지 용수확보와 홍수예방, 하천환경관리 등의 목적으로 많은 댐이 건설되어 왔으며 이러한 댐 건설은 주변지역의 자연 및 사회 환경의 변화를 유발하게 된다. 이는 구체적으로 유출특성의 변화로 나타나며 유출특성의 변화는 수자원의 계획과 관리 측면에 상당한 영향을 끼친다. 따라서 정확한 장기유출량의 예측은 이수 측면에서 대단히 중요하며 이에 대한 신뢰성 있는 해석이 수행되어야 한다. 본 연구에서는 SWAT 모형을 이용하여 댐 건설에 따른 유역의 장기유출특성변화를 분석하였다. 충주댐 상류유역을 대상으로 분석기간을 댐 건설 전(1975~1985년)과 댐 건설 후(1986~1995년, 1996~2005년)로 나누어 적용하였고, 해당 관측소에서 제공하는 수문 기상자료와 지형자료를 이용하여 입력자료를 구축하였다. SWAT 입력 모형의 최적값을 결정하기 위해 유출총량 및 첨두유량 감쇄곡선 형태에 영향을 미치는 유출관련 매개변수를 선정하여 보정하였고, 유역 최종 출구점인 충주댐 지점에서의 일 유출자료에 대해 관측치와 모의치를 비교하였다. 그 결과 상관계수는 0.89와 0.71, 모형효율은 0.87과 0.76으로 매우 양호한 결과를 보였으며 이는 SWAT 모형이 장기 유출 모의에 있어 안정적 결과를 제공함을 판단할 수 있었다. 보정된 결과를 바탕으로 장기유출모의결과 계산평균유량과 계산첨두유량 모두 관측결과와 상대오차 10%이하의 만족스러운 결과를 보였으며 댐 건설 전 후의 유출특성 비교결과 전반적으로 댐 건설 이후 유출률이 증가하는 특성이 나타났다. 댐 건설 후 나타나는 유출률 변화를 규명하고자 수문성분별 모의를 실시하였으며 그 결과 지표유출이 4% 증가 하였고 증발산량이 3% 감소하였다. 이는 대상유역의 도시화에 의한 불투수면적의 증가와 산림면적 감소 때문으로 추정되며, 이로 인하여 댐 건설 후 유출률이 소폭 증가하였음이 판단된다. 이상의 결과들로부터 SWAT 모형은 장기 일 유출량 추정 및 유역 전반의 통합관리 측면에서 적용성과 활용성이 우수하다고 판단되며 댐 건설로 인한 자연환경의 변화는 유역의 유출특성의 변화에 영향을 준다는 결론을 얻을 수 있었다. 이러한 결과를 확장하여 댐 건설 이외에 다양한 요소들을 모형에 적용하고 유역개발에 따른 수문환경의 전반적인 변화에 대한 유출평가가 필요하다고 판단된다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.81-90
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• 2012

The indentation test, which is one of the testing methods for evaluating the mechanical properties of materials, can be applied to the evaluation of creep properties. Many studies related to the indentation creep test, however, have just focused on the characteristics of the steady-state creep, so there are wide discrepancies between the uniaxial test and the indentation test. To obtain accurate creep properties, it is therefore important to consider the effects of transient creep. In the present work, the Ogbonna et al.'s work on the spherical indentation test including the transient creep was expanded and applied to the conical indentation creep test. The characteristics of the transient creep were analyzed via finite element simulations and compared with those obtained through spherical indentation. Other effects, such as elastic strain, indenter shape, contact area, and representative strain, which have not been considered properly in prior studies on the creep test, are also discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4101-4106
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• 2011

In this study, we propose that the structures of 2-layer spiral planar inductors have a lower spiral coil and via increasing inductance in limited possession are and confirm the frequency characteristics. The structures of inductors have Si thickness of $300{\mu}m$, $SiO_2$ thickness of $7{\mu}m$. The width of Cu coils and the space between segments have $20{\mu}m$, respectively. The number of turns of coils have 3. The performance of spiral planar inductors was simulated to frequency characteristics for inductance, quality-factor, SRF(Self- Resonance Frequency) using HFSS. The 2-layer spiral planar inductors have inductance of 3.2nH over the frequency range of 0.8 to 1.8 GHz, quality-factor of maximum 8.2 at 2.5 GHz, SRF of 5.8 GHz. Otherwise, 1-layer spiral planar inductors have inductance of 1.5nH over the frequency range of 0.8 to 1.8 GHz, quality-factor of maximum 18 at 8 GHz, SRF of 19.2 GHz.