• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.11
• /
• pp.4084-4104
• /
• 2021

Visual place recognition (VPR) is a fundamental yet challenging task of mobile robot navigation and localization. The existing VPR methods are usually based on some pairwise similarity of image descriptors, so they are sensitive to visual appearance change and also computationally expensive. This paper proposes a simple yet effective four-step method that achieves adaptive convolutional neural network (CNN) landmark matching for VPR. First, based on the features extracted from existing CNN models, the regions with higher significance scores are selected as landmarks. Then, according to the coordinate positions of potential landmarks, landmark matching is improved by removing mismatched landmark pairs. Finally, considering the significance scores obtained in the first step, robust image retrieval is performed based on adaptive landmark matching, and it gives more weight to the landmark matching pairs with higher significance scores. To verify the efficiency and robustness of the proposed method, evaluations are conducted on standard benchmark datasets. The experimental results indicate that the proposed method reduces the feature representation space of place images by more than 75% with negligible loss in recognition precision. Also, it achieves a fast matching speed in similarity calculation, satisfying the real-time requirement.

• Structural Engineering and Mechanics
• /
• v.1 no.1
• /
• pp.103-118
• /
• 1993

The near field is discretized into finite elements, and the far field into infinite elements. Closed form far-field solutions to three fundamental problems are used as the shape functions of the infinite elements. Such infinite elements are capable of transmitting all surface and body waves. An efficient scheme to integrate numerically the stiffness and mass matrices of these elements in presented. Results agree closely with those obtained by others.

• Journal of the Korean Physical Society
• /
• v.73 no.10
• /
• pp.1577-1583
• /
• 2018

Tumor-treating fields therapy involves placing pads onto the patient's skin to create a low- intensity (1 - 3 V/cm), intermediate frequency (100 - 300 kHz), alternating electric field to treat cancerous tumors. This new treatment modality has been approved by the Food and Drug Administration in the USA to treat patients with both newly diagnosed and recurrent glioblastoma. To deliver the prescribed electric field intensity to the tumor while minimizing exposure of organs at risk, we developed an optimization method for the electric field distribution in the body and compared the electric field distribution in the body before and after application of this optimization algorithm. To determine the electric field distribution in the body before optimization, we applied the same electric potential to all pairs of electric pads located on opposite sides of models. We subsequently adjusted the intensity of the electric field to each pair of pads to optimize the electric field distribution in the body, resulting in the prescribed electric field intensity to the tumor while minimizing electric fields at organs at risk. A comparison of the electric field distribution within the body before and after optimization showed that application of the optimization algorithm delivered a therapeutically effective electric field to the tumor while minimizing the average and the maximum field strength applied to organs at risk. Use of this optimization algorithm when planning tumor-treating fields therapy should maintain or increase the intensity of the electric field applied to the tumor while minimizing the intensity of the electric field applied to organs at risk. This would enhance the effectiveness of tumor-treating fields therapy while reducing dangerous side effects.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.383-383
• /
• 2011

Generally, field emitters can be categorized into two types according to the emitter shape, one is a planar field emitter and the other is a point emitter. The planar field emitter is used for displays, flat lamps and signage boards. On the other hands, the point field emitter is expected to play a significant role in x-ray sources and electron beam sources. Such applications of the point field emitters, especially, need large emission current and high emission stability with a small electron beam size. A few reports announced point emitters made by carbon nanotubes (CNTs). However, they still have suffered from poor reproducibility and low emission current. Here, we demonstrated high performance CNT point emitters by attaching CNTs onto graphite rod. Graphite rod exhibited good electrical conductivity and chemical stability. In this method, the shape of the point emitter could be easily controlled by changing the length and diameter of the graphite rod. The CNT point emitter showed emission current over 1 mA at an applied electric field of 1.4 V/${\mu}m$. We consider that the stable emission performance is attributed to the stable contact between CNTs and graphite rod.

• Nuclear Engineering and Technology
• /
• v.53 no.2
• /
• pp.618-625
• /
• 2021

In this paper, the single-photon avalanche diodes (SPADs) featuring three different p-well implantation doses (∅_p-well) of 5.0 × 10¹², 4.0 × 10¹², and 3.0 × 10¹² atoms/cm² under the identical device layouts were fabricated and characterized to evaluate the effects of field enhanced mechanisms on primary dark pulses due to the maximum electric field. From the I-V curves, the breakdown voltages were found as 23.2 V, 40.5 V, and 63.1 V with decreasing ∅_p-well, respectively. By measuring DCRs as a function of temperature, we found a reduction of approximately 8% in the maximum electric field lead to a nearly 72% decrease in the DCR at V_ex = 5 V and T = 25 ℃. Also, the activation energy increased from 0.43 eV to 0.50 eV, as decreasing the maximum electric field. Finally, we discuss the importance of electric field engineering in reducing the field-enhanced mechanisms contributing to the DCR in SPADs and the benefits on the SPADs related to different types of radiation detection applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.12
• /
• pp.1454-1459
• /
• 2010

This paper presents the comparison of electric field penetration in Bell laboratories and IEC 61000-2-9 standard when HEMP source penetrates through an aperture in a planar conducting plane of infinite extent. HEMP electric field distributions assume in order to interpret this problem. Integral equation is derived and solved by Galerkin's method of moments for calculating the penetrating electric field. It is shown that penetrated electric field of IEC 61000-2-9 standard is greater than the Bell Laboratories waveform in resonance of lower frequency band, but those waveforms are similar in shape to frequency domain.

• Proceedings of the Korea Association of Crystal Growth Conference
• /
• 1997.06a
• /
• pp.243-246
• /
• 1997

A new technique for low temperature crystallization of amorphous silicon, called field aided lateral crystallization(FALC) was attempted. To demonstrate the concept of FALC, thin layer of nickel(30${\AA}$) was deposited on top of amorphous silicon film and the electric field was applied during the crystallization. The effects of electric field on the crystallization behavior of amorphous silicon film were investigated.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08a
• /
• pp.778-781
• /
• 2007

The dispersion of carbon nanotubes in composite and their field emission superiority have been discussed. Four synthesis methods have been studied. The CNT-composite, synthesized by the combination of the chemical and mechanical dispersion routes shows superior dispersion as well as field emission characteristics as compared to other syntheses methods.

• Journal of Korean Society on Water Environment
• /
• v.25 no.5
• /
• pp.682-688
• /
• 2009

A plane field and a sloped field located at low-land plane and alpine areas, respectively, were monitored with respect to runoff, water quality and fertilizer uses from March to December, 2008. Runoff volume and Non-Point Source (NPS) loads were estimated and analyzed with respect to fertilizer uses. Total TN and TP loads from the sloped field were higher than those from plane field because of larger chemical uses in the alpine field than in the plane field. Organic matter load from plane field was higher than that from sloped field because more organic compost was applied to plane field than to sloped field. Event Mean Concentration (EMC) of measured water quality indices were relatively higher in both fields. Organic matter load per 1 mm rainfall were higher in plane field and TN and TP loads per 1 mm rainfall were higher in sloped field than those in respective comparing field. It was concluded that the type and application method of fertilizer could play an important role in the estimation of NPS pollution loads and the development of Best Management Practices (BMPs). However, it was recommended that long-term monitoring is necessary to better describe the relationship between fertilizer uses and water quality from agricultural fields because numerous natural and management factors other than fertilizer also affect runoff quality.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.11a
• /
• pp.498-501
• /
• 2006

When an object or objects, rigid or flexible, presents in incident sound field, the sound wave is scattered. This, we call, is scattered sound field. It, of course, depends on the amplitude and the direction of the incident sound field as well as the geometry and the surface impedance of the scatterer(object). This paper addresses the way to measure scattered sound field by using arbitrary incident sound wave. This means that the method can decompose the scattered field from measured sound field with respect to any magnitudes and directions of incident plane-waves.