• Journal of the Korean Geographical Society
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• v.40 no.5 s.110
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• pp.514-532
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• 2005

The purpose of this study is to critically examine conventional spatial measures of individual accessibility, which are based on the notion of spatial proximity, the single reference location, and the unlinked travel model. Using space-time accessibility measures with the travel-activity diary data set of Portland Metro, US, three expectations from spatial measures on spatial patterns of individual accessibility were empirically examined: (1) does individual accessibility decrease with an increase of distance from the CBD?; (2) does the spatial pattern of accessibility resemble that of urban opportunity density pattern?; and (3) are spatial patterns of individual accessibility of different socio- demographic population groups basically similar as people in the same area share the same geographic characteristics regardless of gender, race, age, and so on? First of all, the results showed that spatial variations in individual accessibility were not directly determined by spatial proximity and opportunity density as suggested by previous accessibility measures. The spatial pattern of individual accessibility was dramatically different from that of urban opportunity density High peaks of accessibility level were found far away from the CBD and regional centers. This finding might be associated with the importance of multi-reference locations and linked travels in shaping accessibility in reality. Furthermore, this study found that spatial patterns of accessibility clearly differ between men and women. These findings suggest that access requires more than proximity, and that the interaction between person-specific space-time constraints and the consequential availability of urban opportunities in space-time renders different accessibility experiences to people even in the same region, which would be one of the key ingredients missing from conventional spatial measures of accessibility.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.31-36
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• 2006

The evaluation of safety of simulated maneuvers is frequently analysed by so called goal line or point of interest. This paper is to suggest that regarding the results of simulation the goal analysis and in length analysis are investigated respectively and the availability of which is effective and is also to suggest closest distance to channel boundary at each ship's position, not centerline, as one of proximity measures.

• Journal of Navigation and Port Research
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• v.32 no.8
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• pp.577-582
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• 2008

In order to ascertain the effect of ship's speeds, in maneuver under the condition of strong cross current in the breakwater channel of Busan port, this paper is to deal with the analyses of vessel proximity measures, vessel controllability measures, and ship handlers' subjective evaluation measures of simulated maneuvers, which were carried out by 76 ship handlers who conned Panamax bulk carrier of 60,000 DWT, The set and drift of current are southwesterly and 2 knots. The speeds of the model ship are 5 knots & 10 knots respectively. The followings are concluded. ${(1)}$ In the approaches of the breakwater of Busan port, ship handlers psychologically tend not to give the drift angle of more than $10^{\circ}$ bemuse ship's head points out of the entrance. ${(2)}$ Ship handlers' subjective evaluation, vessel proximity and controllability measures are relatively larger under the speed of 5 knots than under that of 10 knots. due to direct pressure of strong current. ${(3)}$ A single index of controllability measures was suggested, by removing their units.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.8
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• pp.619-626
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• 2016

This paper proposes the design and performance evaluation of a marine engine fault detection system using a proximity sensor for marine engine. Non-linearity is greatly reduced by using the sensor without increasing the response time by applying the CANopen protocol. The CANopen protocol enables the sensor to send initial values and measurement data. The marine engine fault detection system measures crankshaft deflection and the bottom dead center of the crosshead in real-time, which maintains stability and prevents the serious breakdown of the marine engine by use of an interlocking alarm monitoring system.

• Wind and Structures
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• v.13 no.1
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• pp.21-36
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• 2010

A new full scale testing apparatus generically named the Wall of Wind (WoW) has been built by the researchers at the International Hurricane Research Center (IHRC) at Florida International University (FIU). WoW is capable of testing single story building models subjected up to category 3 hurricane wind speeds. Depending on the relative model and WoW wind field sizes, testing may entail blockage issues. In addition, the proximity of the test building to the wind simulator may also affect the aerodynamic data. This study focuses on the Computational Fluid Dynamics (CFD) assessment of the effects on the quality of the aerodynamic data of (i) blockage due to model buildings of various sizes and (ii) wind simulator proximity for various distances between the wind simulator and the test building. The test buildings were assumed to have simple parallelepiped shapes. The computer simulations were performed under both finite WoW wind-field conditions and in an extended Atmospheric Boundary Layer (ABL) wind flow. Mean pressure coefficients for the roof and the windward and leeward walls served as measures of the blockage and wind simulator proximity effects. The study uses the commercial software FLUENT with Reynolds Averaged Navier Stokes equations and a Renormalization Group (RNG) k-${\varepsilon}$ turbulence model. The results indicated that for larger size test specimens (i.e. for cases where the height of test specimen is larger than one third of the wind field height) blockage correction may become necessary. The test specimen should also be placed at a distance greater than twice the height of the test specimen from the fans to reduce proximity effect.

• Korean Security Journal
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• no.38
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• pp.137-161
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• 2014

The aim of this study was to investigate the factors influencing on housebreaking victimization in South Korea. It is important that a resident, police officer, and policy makers use Routine activities/lifestyle theory in order to explore whether proximity and exposure to offenders or presence of guardianships affect the resident's risk of being victimized. In this context, the current study utilizes proximity variables: disorder of residence, exposure variables: hours of empty house and guardianship variables: social networks, security equipment. The study employs secondary data(Korean Crime Victim Survey in 2008) responses from a sample of 4, 710 resident. and Logistic regression analysis was used to examine whether the likelihoods of housebreaking victimization was associated with the measures of proximity and exposure and the lack of guardianship. The result of the study showed that proximity(disorder of residence) and guardianship (security equipment) are statistically significant predictors that is associated with an enhanced risk of school violence victimization while controlling for other variables. Further policy implications of the study will be discussed.

• Journal of Navigation and Port Research
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• v.31 no.1 s.117
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• pp.1-6
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• 2007

The evaluation of safety of simulated maneuvers is frequently analysed by so called goal-line or point of interest in Korea. For the purpose of warning the risk in the proximity measure composed of only the goal-line analysis, this paper utilized Korea Institute of Maritime and Fisheries Technology(KIMFT) which houses a real-time, full-mission shiphandling simulator to examine the goal-line and in-length analyses in the outbound channel of Kwangyang port as an example. It used a 15,000 TEU container ship as a model under environmental conditions of the northwestly 26-knot wind and 2.2-knot ebb current. The result of two analyses showed the probability invading the channel boundary obtained by the goal-line analysis is a little greater than that of the in-length analysis. Therefore it was acknowledged that the proximity measure by the goal-line analysis alone may be followed by some risk. In addition, this paper was to suggest the closest distance to channel boundary from the ship's edge as one of proximity measures, instead of using the ship's deviation from the centerline of channel.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.1063-1070
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• 2005

Number of subway train units that Seoul Metropolitan Subway Corporation as at September 2005 is 1.944 on 4 routes from 60 units at the time of commencement of operation, having grown exponentially. Along with increase in the number of passengers the role of subway as safer and expedient means of transportation is now being required. Furthermore, the Corporation has been researching on means of improving the safety and reliability of subway entry/exit doors which has become an essential task and directly effect the safety of the passengers. In this Study, has developed sensory control system for the entry/exit door of the subway train using non-contact proximity sensor as a part of review of and measures against various issues of entry/exit door of the subway trains currently under operation. In addition, this sensor system was verified through test production and tests. If this technology becomes commercialized and practically utilized in the future, it would be able to make definite contribution to the safer transportation of passengers.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.36
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• pp.275-285
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• 1995

In recent years there has been increasing interest in the issue of process centering in manufacturing process, The traditional process capability indices Cp, Cpk and Cpu are used to provide measure of process performance, but these indices do not represent the issue of process centering. A new measure of the process capability index Cpm is proposed that takes into account the proximity to the target value as well as the process variation when assessing process performance. However, Cpm only considers acceptance cost for deviation from target value within specification limits, do not includes economic consideration for rejected items. This paper proposes flexible process performance measures that considered quadratic loss function caused by quality deviation within specification limits, rejection cost associated with the disposition of rejected items, and inspection cost. In this model disposition of rejected items are considered under perfect corrective procedures and the absence of perfect corrective procedures.

• Journal of the Korean Society for information Management
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• v.33 no.2
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• pp.61-76
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• 2016

This study aims at proposing three prestige indices-closeness prestige, input domain, and proximity prestige- as useful measures for the impact of a particular node in citation networks. It compares these prestige indices with other impact indices as it is still unknown what dimensions of impact these indices actually measure. The prestige indices enable us to distinguish the most prominent actors in a directed network, similar to the centrality indices in undirected networks. Correlation analysis and principal component analysis were conducted on the author citation network to identify the differentiated implications of the three prestige indices from the existing impact indices. We selected simple citation counting, h-index, PageRank, and the three kinds of centrality indices which assume undirected networks as the existing impact measures for comparison with the three prestige indices. The results indicate that these prestige indices demonstrate distinct impact dimension from the other impact indices. The prestige indices reflect indirect impact while the others direct impact.