• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.6
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• pp.36-46
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• 2016

Separate transportation card readers that record the amount of transfer volume occurring during movement in-between lines within the metropolitan railway transfer stations do not exist. This research proposes a model to estimate passenger transit movements in transfer stations that adequately reproduces characteristics arising during a transfer trip. The model used in this study assumes that passengers adopt transfer behaviors that minimize their generalized costs during transfer trips. Further, two measures are sought in order to reflect attributes of the metropolitan railway. The first is that similar paths connect origin and destination stations. For this, the M-Similar Paths method is applied to the model to identify the similar paths that arise. The second is that passengers perceive increasing number of transfers as additional transfer costs, which is reflected by means of the Stepwise Transfer Coefficient. Two case studies of metropolitan railway are used to propose measures for analysis of transfer trips. Twenty directional transit phenomena are reproduced for Sindorim railway station. Aggregate directional transit(A), aggregate inter-line transit(B), and B/A are calculated on a percentage basis for 33 metropolitan railway transfer stations, and using this, the functional role of transfers is explored.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.2
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• pp.1-12
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• 2017

The Seoul metropolitan transportation card's high value lies in its recording of total population movements of the public transit system. In case of recorded information on transit by bus, even though route information utilized by each passenger is accurate, the lack of passenger transfer information of the urban railway makes it difficult to estimate correct routes taken by each passenger. Therefore, pinpointing passenger path selection patterns arising in the metropolitan railway network and using this as part of a path movement estimation model is essential. This research seeks to determine that features of passenger movement routes in the urban railway system is comprised of M-similar routes with increasing number of transfer reflected as additional costs. In order to construct the path finding conditions, an M-similar route searching method is proposed, embedded with non additive path cost which appears through inclusion of the stepwise transportation parameter. As well, sensitivity of the M-similar route method based on transportation card records is evaluated and a stochastic trip assignment model using M-similar path finding is constructed. From these, link trip and transfer trip results between lines of the Seoul metropolitan railway are presented.

• Journal of the Korean Mathematical Society
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• v.57 no.2
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• pp.451-470
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• 2020

Let C[0, T] denote an analogue of Wiener space, the space of real-valued continuous functions on the interval [0, T]. For a partition 0 = t₀ < t₁ < ⋯ < t_n < t_n+1 = T of [0, T], define X_n : C[0, T] → ℝⁿ⁺¹ by X_n(x) = (x(t₀), x(t₁), …, x(t_n)). In this paper we derive a simple evaluation formula for Radon-Nikodym derivatives similar to the conditional expectations of functions on C[0, T] with the conditioning function X_n which has a drift and does not contain the present position of paths. As applications of the formula with X_n, we evaluate the Radon-Nikodym derivatives of the functions ∫₀^T[x(t)]^mdλ(t)(m∈ℕ) and [∫₀^Tx(t)dλ(t)]² on C[0, T], where λ is a complex-valued Borel measure on [0, T]. Finally we derive two translation theorems for the Radon-Nikodym derivatives of the functions on C[0, T].

• Korean Journal of Environment and Ecology
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• v.17 no.3
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• pp.232-241
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• 2003

Mountain Chungyeong, 879m in altitude, is located in the northeast of the middle area in Korea. Around Mt. Chungyeong, many Korean endemic and rare plants are populated, so it is considered a very important biogeographical area where the temperature zones of northern and southern plants are crossed. Because it is close to Seoul, a capital of Korea, it is a common mountain where many tourists visit frequently. Continuous tourist's visit may cause a bad influence on vegetation around the climbing paths. Therefor, weed community around the climbing paths on Mt. Chungyeong, where visitors exert a bad influence directly on its community by coming in and out, was surveyed phytosocialogically. Our surveys have been accomplished from August, 2001 to September, 2002. weed communities formed around the climbing paths on Mt. Chungyeong were divided into several patterns and analysed. They have been divided into 5 communities and 5 subcommunities. Community A: Plantago asiatica community, A-a: Erigeron annuus subcommunity, A-b: Carex. lanceolata subcommunity, B: Pseudostellaria palibiniana community, B-a: Carex siderosticta subcommunity, B-b: Galium trachyspermum subcommunity, C: Pueraria thunbergiana community, D: Lespedeza maximowiczii community, E: Rubus crataegifolius community, F: Oplismenus undulatifolius community, The flora surveyed in these communities was constituted of 47 families, 101 genera, 17 varieties, and 149 species. Wild plants such as Plantago asiatica, Erigeron annuus, Erigeron strigosus, Pueraria thunbergiana, Lespedeza maximowiezii, Rubus crataegifolius, Artemisia princeps var. orientalis, Artemisia japonica and Lysimachia clethroides were mostly light loving plants and higher resistant plants against the stamping pressure. Our result from the ranking all surveyed areas by the Bray-Curtis ordination method was very similar to the results from phytosocialogical table analysis.

• The Journal of the Acoustical Society of Korea
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• v.25 no.4
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• pp.184-190
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• 2006

Recently, Lee et al. have proposed an algorithm utilizing the signals from different paths by using bottom mounted simple linear array to estimate 3-D location of oceanic target. But this algorithm assumes that sound velocity is constant along depth of sea. Consequently, serious performance loss is appeared in real oceanic environment that sound speed is changed variously. In this paper, we present a 3-D near field localization algorithm for inhomogeneous sound speed. The proposed algorithm adopt localization function that utilize ray propagation model for multipath environment with linear sound speed profile(SSP), after that, the proposed algorithm searches for the instantaneous azimuth angle, range and depth from the localization cost function. Several simulations using linear SSP and non linear SSP similar to that of real oceans are used to demonstrate the performance of the proposed algorithm. The estimation error in range and depth is decreased by 100m and 50m respectively.

• ETRI Journal
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• v.35 no.4
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• pp.697-705
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• 2013

Emerging trends in the area of digital very large scale integration (VLSI) signal processing can lead to a reduction in the cost of the cochlear implant. Digital signal processing algorithms are repetitively used in speech processors for filtering and encoding operations. The critical paths in these algorithms limit the performance of the speech processors. These algorithms must be transformed to accommodate processors designed to be high speed and have less area and low power. This can be realized by basing the design of the auditory filter banks for the processors on digital VLSI signal processing concepts. By applying a folding algorithm to the second-order digital gammatone filter (GTF), the number of multipliers is reduced from five to one and the number of adders is reduced from three to one, without changing the characteristics of the filter. Folded second-order filter sections are cascaded with three similar structures to realize the eighth-order digital GTF whose response is a close match to the human cochlea response. The silicon area is reduced from twenty to four multipliers and from twelve to four adders by using the folding architecture.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.5
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• pp.91-99
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• 2019

Existing node-to-node based optimal path searching is built on the assumption that all destination nodes can be arrived at from an origin node. However, the recent appearance of the adaptive path search algorithm has meant that the optimal path solution cannot be derived in node-to-node path search. In order to reflect transportation data at the links in real-time, the necessity of the node-to-link (or link-to-node; NL) problem is being recognized. This research assumes existence of a network with link-label and non-additive path costs as a solution to the node-to-link optimal path problem. At the intersections in which the link-label has a turn penalty, the network retains its shape. Non-additive path cost requires that M-similar paths be enumerated so that the ideal path can be ascertained. In this, the research proposes direction deletion and turn restriction so that regulation of the loop in the link-label entry-link-based network transformation method will ensure that an optimal solution is derived up until the final link. Using this method on a case study shows that the proposed method derives the optimal solution through learning. The research concludes by bringing to light the necessity of verification in large-scale networks.

• The Journal of the Acoustical Society of Korea
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• v.32 no.4
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• pp.308-316
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• 2013

A set of experiments (Shallow Water 2006, SW06) was carried out in shallow water near the New Jersey shelf break in summer 2006. Significant fluctuations in direct and surface reflected arrivals were observed from the chirp data (1100~2900 Hz) measured on a vertical line array. This paper presents a geoacoustic inverssion technique for short-range acoustic data with fluctuating arrivals and inversion results of experimental data. In order to reduce effects of random sea surface on the inversion, the acoustic energy back-propagated from the array to the source through direct and bottom-reflected paths is defined as the objective function. A multi-step inversion scheme is applied to the data using VFSR (Very Fast Simulated Reannealing) optimization technique. The inversion results show a source depth oscillation period equal to the measured ocean surface wave period. The inverted bottom sound speed is 1645 m/s and is similar to that estimated by other work at the same site.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.3
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• pp.170-179
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• 1999

The SUS (Signal, Underwater Sound)-OAT experiment was carried out in the Ulleung Basin of the East Sea on 3 June 1997. The SUS-OAT system consisted of aircraft deployed shots as sources and a vertical line array (VLA) tethered by a receiver ship was used to survey a large area where a mesoscale warm eddy appears frequently. The experiment was carried out such that explosive charges set to detonate at 800 ft depth were dropped in a rectangular ($120{\times}120$ km). Sources were a rapidly deployable SUS charge (MK 61 MOD 0), and receiver is a fixed VLA, 90 m in length (150-240 m in receiver depth), composed of 10 elements equally spaced. The reference ray paths are computed by range-dependent acoustic model in canonical ocean based on the historical data. The singular value decomposition (SVD) method is used to obtain the horizontal perturbation of the temperature fields. Horizontal distributions of temperature fields at 150 m and 200 m depth show a weak warm eddy observed by AXBT and the inversely estimated temperature shows similar patterns in terms of the location of the warm eddy. In conclusion, the SUS-OAT experiment has been successful to estimate the position of warm eddy and its temperature field in the East Sea of Korea.

• The Journal of Korean Institute of Next Generation Computing
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• v.14 no.6
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• pp.57-65
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• 2018

Conventional RF signal-based indoor localization techniques such as BLE or Wi-Fi based fingerprinting method show considerable localization errors even in small-scale indoor environments due to unstable received signal strength(RSS) of RF signals. Therefore, it is difficult to apply the existing RF-based fingerprinting techniques to large-scale indoor environments such as airports and department stores. In this paper, instead of RF signal we use the geomagnetic sensor signal for indoor localization, whose signal strength is more stable than RF RSS. Although similar geomagnetic field values exist in indoor space, an object movement would experience a unique sequence of the geomagnetic field signals as the movement continues. We use a deep neural network model called the recurrent neural network (RNN), which is effective in recognizing time-varying sequences of sensor data, to track the user's location and movement path. To evaluate the performance of the proposed geomagnetic field based indoor positioning system (IPS), we constructed a magnetic field map for a campus testbed of about $94m{\times}26$ dimension and trained RNN using various potential movement paths and their location data extracted from the magnetic field map. By adjusting various hyperparameters, we could achieve an average localization error of 1.20 meters in the testbed.