• Journal of the Korean Institute of Rural Architecture
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• v.18 no.3
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• pp.25-34
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• 2016

The purpose of this study is to investigate installation status of information facilities and condition of walking road influencing to psychological safety of walking tourists. For this purpose, four roads for walking tour are selected; the course no. 16 of Jeju Olle Trail, Sarabong Byeoldobong walkway in Jeju and the course no. 8 of Bougil, Gyeongpo Lake walkway in Gangneung. Facilities installed on roads for walking tour are classified into four facilities; safety facility, information facility, amenity facility, local cultural facility. In order to consider installation status of information facilities and condition of walking road influencing to psychological safety of walking tourist, a field experiment was conduced focusing on the course no. 16 of Jeju Olle Trail. Thirteen cases were happened as confusing situation while walking tour. Of the 13 cases, the situation of being lost and wandering on the trail accounted for six cases. In contrast to the expectation that the situation of being lost and wandering would occur only at a crossroads, it is not that such situation took place at specific places like a crossroads or where direction signs were inaccurate. Walking tourists of this field experiment also confronted situations of having lost confidence about continuing the ongoing direction, of having anxiety over walking a walking trail, of feeling discomfort caused by walking and of being offended by uncomfortable or messy areas of walking trial. These confusing situations are happened inappropriate installation of direction sign, so direction sign is needed to install more carefully and detailed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6A
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• pp.839-847
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• 2000

A digital subscriber line(DSL) has been introduced recently in home and abroad to deliver high speed Internet access services with the large channel and the sheer number of subscribers. It has been processed to standardize the DSL in our country, but the analysis on the DSL is limited to the field trials. Therefore, in this paper we have proposed the techniques related to analysis on the performances of DSL, and estimated its S/N and BER performances. In particular, the channel capacity gained from S/N values was compared with the field trial results in Japn and it was known that the results from this study was proved to be valid. Also, the S/N performance of DSL is degraded due to only Gaussian noise, and BER performance degraded greatly with both the higher frequency and the longer distance. However, results of this analysis can be used as the basic data in specifying the standardization of DSL in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4087-4094
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• 2010

The sensor data which is measured by Quadruped robot is utilized to recognize the physical environment or other information and to control the posture and walking of robot system. In order to control the robot precisely, high accuracy of sensor data is required, most of these sensors however, belongs to expensive and low-durable products. Moreover, these are exposed excessive load operation in a field condition if it is applied to field robot system. This issue becomes more serious one when the robot system is manufactured as a mass product. As in this context, this study suggests a virtual sensor technology to alternate or assist the main sensor system. This scheme is realized by using back-propagation algorithm of neural network theory, and the quality of estimated sensor data could be improved through the algorithmic and hardware based treatments. This study performs the various trial to identify the effective parameters which effect to the quality and reliability of estimated sensor data and tries to show the possibility of proposed methodology.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.4
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• pp.602-608
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• 2012

This study was conducted to evaluate the effect of commercial extruded pellet (EP) diet on the growth and water quality compared with a raw fish moist pellet (MP) diet for flounder on field feeding experiments. Three replicate groups of 130 fish per each tank (initial weight of 380 g) were fed one of the EP and Moist pellet (MP) for 7 months. In field feeding experiment, no significant difference was observed in final mean weight of fish fed the experimental EP (1,233 g) and MP (1,237 g), and any noticeable problem caused by feeding the experimental EP was not found during the whole period of feeding trial. Feed efficiency of fish fed the experimental EP was higher than that of MP, and there was no significant difference in survival between the fish fed experimental EP and MP. The concentrations of SS, COD, TN and TP of seawater in tanks of MP groups were 1-5 times higher than those of EP groups. Therefore, these results strongly suggest that diet EP could be developed to replace MP diet for the marketable size of production for flounder without adverse effects on growth performance and water quality.

• Korean Journal of Ophthalmology
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• v.32 no.6
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• pp.470-477
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• 2018

Purpose: To investigate the relationship between the progression of visual field (VF) loss and changes in lamina cribrosa depth (LCD) as determined by spectral-domain optical coherence tomography (SD-OCT) enhanced depth imaging in patients with primary open angle glaucoma (POAG). Methods: Data from 60 POAG patients (mean follow-up, $3.5{\pm}0.7$ years) were included in this retrospective study. The LCD was measured in the optic disc image using SD-OCT enhanced depth imaging scanning at each visit. Change in the LCD was considered to either 'increase' or 'decrease' when the differences between baseline and the latest two consecutive follow-up visits were greater than the corresponding reproducibility coefficient value ($23.08{\mu}m$, as determined in a preliminary reproducibility study). All participants were divided into three groups: increased LCD (ILCD), decreased LCD (DLCD), and no LCD change (NLCD). The Early Manifest Glaucoma Trial criteria were used to define VF deterioration. Kaplan-Meier survival analysis and Cox's proportional hazard models were performed to explore the relationship between VF progression and LCD change. Results: Of the 60 eyes examined, 35.0% (21 eyes), 28.3% (17 eyes), and 36.7% (22 eyes) were classified as the ILCD, DLCD, and NLCD groups, respectively. Kaplan-Meier survival analysis showed a greater cumulative probability of VF progression in the ILCD group than in the NLCD (p < 0.001) or DLCD groups (p = 0.018). Increased LCD was identified as the only risk factor for VF progression in the Cox proportional hazard models (hazard ratio, 1.008; 95% confidence interval, 1.000 to 1.015; p = 0.047). Conclusions: Increased LCD was associated with a greater possibility of VF progression. The quantitative measurement of LCD changes, determined by SD-OCT, is a potential biomarker for the prediction of VF deterioration in patients with POAG.

• Korean Journal of Heritage: History & Science
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• v.55 no.3
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• pp.178-188
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• 2022

This article cites examples of cultural heritages that urgently require protection measures, and the reinterpretation of beacons, fortresses, and extremities identified in the process of conducting a cultural heritage investigation of the DMZ and bordering areas. It is true that there are various difficulties involved in implementing thorough protection measures considering the reality of the two Koreas' division. Despite this, the "Ordinance for the Protection of Military Cultural Properties" and the "Act on the Protection and Investigation of Buried Cultural Heritage" have been enacted and are in effect. In particular, in the "Ordinance for the Protection of Military Cultural Properties," the value of protecting "military assets" is emphasized. The identification and investigation of cultural heritages in the DMZ and border areas must continue. Although field research is currently difficult, the primary investigation conducted by high-altitude terrain analysis and literature research is considered effective. Furthermore, there are parts that require correction and supplementation with future field investigations. Although some trial and error is expected during these various cultural heritage investigations, they need to continue.

• Tribology and Lubricants
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• v.39 no.1
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• pp.1-7
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• 2023

Fluid pumps in chemical processes are typically driven by electric motors. Even if the motor is separated from the pump with seals, wear resulting from friction and misalignment can lead to leakage of chemical fluid, causing corrosion in the bearing supporting the motor, and, eventually, failure of the motor. It is thus a standard procedure to replace bearings at regular intervals. In this article, we propose 3D-printed plastic ball bearings for use as an alternative to commercial stainless-steel ball bearings. The plastic bearings are easy to manufacture, require less time to replace, and are chemically resistant. To validate the applicability of the plastic bearings, we first conducted chemical resistance tests. Bearings were immersed in 30 caustic acid and 30 nitric acid for 30 min and 24 h, respectively. The test results showed no corrosive damage to the bearings. A test rig was set up to compare the performance of the plastic bearings with that of the commercially equivalent deep-groove ball bearings. Loading test results showed that the plastic bearings performed as well as the commercial bearing in terms of vibration level and load-handling capability. Finally, a plastic bearing was subjected to a clean-in-place process for three months. It actually outperformed the commercial bearing in terms of chemical resistance. Thus, 3D-printed plastic bearings are a viable alternative to stainless-steel ball bearings.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.814-816
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• 2002

Because there is a strong interaction between the arc discharge and their surroundings, it is not easy to predict the characteristics of industrial arc plasma systems such as gas circuit breakers. The design procedure of these systems is still largely based on trial and error, although the situation is rapidly improving because of the available computational power at a cost in which is still coming down. The desire to predict the behavior of arc plasma systems, thus optimizing and reducing the develpment cost, has been the motivation of these arc researches. In this paper. we have simulated the switching operation of a gas circuit breaker during high current area using a computational fluid dynamics considered the electric field analysis, the radiation model and the effeects of turbulence.

• Korean Journal of Organic Agriculture
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• v.5 no.1
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• pp.67-77
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• 1996

The Organic agricultural techinques were investigated through the observations made for 3 years of the actual conditions of a farmer who has been practicing organic agriculture over 21 years. The farmer was a member of the Ichijima-cho Organic Agriculture Association. The Farmer had not performed much of the organic agricultural techinques at the beginning of his farming history. However, he has gradually developed techniques upon the experiences with trial and error. The notable characteristic of his basic organic agriculture was the utilization of a suitable organic fertilizer to make the soil fertile. Crop damages by diseases and insect pests were prevented through a fertile soil, raising of good seedlings, adoption of tolerant varieties and planting at a wide spacing and consequently considering not to use chemical pesticides. Introduction of power weeder for weed control and paddy-upland crop rotation reduced the cost of production for farming. The crop pattern and method of land us such as mix cropping, crop rotation and conversion of paddy field-upland fieldd were appeared to be very important in organic agriculture. The organic agricultural techniques get systematized upon the adaptation the regional ecology and the development of skills of the farmer. The most important point to achieve the success in organic agriculture system is not only by the development of the technical matters but also by the building of healthy relation and understandings between producers and consumers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6B
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• pp.334-341
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• 2007

A Mobile IP is considered for the efficient mobility function in IEEE 802.16/WiBro environment. However, during the deployment of WiBro, only some of the ACRs(Access Control Router) can support the Mobile IP function. Therefore, a WiBro network can not support the mobility function for the mobile node. In this paper, we implement an overlay-based Mobile IP function and measure the performance through a field trial. Moreover, we evaluate the possibility of commercial deployment and suggest areas that need to be improved.