• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.3
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• pp.679-690
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• 2015

The need to remove the cause of traffic accidents by improving the engineering system for a vehicle and the road in order to minimize the accident hazard. This is likely to cause traffic accident continue to take a large and significant social cost and time to improve the reliability and efficiency of this generally poor road, thereby generating a lot of damage to the national traffic accident caused by improper environmental factors. In order to minimize damage from traffic accidents, the cause of accidents must be eliminated through technological improvements of vehicles and road systems. Generally, it is highly probable that traffic accident occurs more often on roads that lack safety measures, and can only be improved with tremendous time and costs. In particular, traffic accidents at intersections are on the rise due to inappropriate environmental factors, and are causing great losses for the nation as a whole. This study aims to present safety countermeasures against the cause of accidents by developing an intersection Traffic safety evaluation model. It will also diagnose vulnerable traffic points through BPA (Back -propagation algorithm) among artificial neural networks recently investigated in the area of artificial intelligence. Furthermore, it aims to pursue a more efficient traffic safety improvement project in terms of operating signalized intersections and establishing traffic safety policies. As a result of conducting this study, the mean square error approximate between the predicted values and actual measured values of traffic accidents derived from the BPA is estimated to be 3.89. It appeared that the BPA appeared to have excellent traffic safety evaluating abilities compared to the multiple regression model. In other words, The BPA can be effectively utilized in diagnosing and practical establishing transportation policy in the safety of actual signalized intersections.

• Archives of design research
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• v.13 no.1
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• pp.209-218
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• 2000

The purpose of this study was to improve the curriculum for industrial design department in the junior colleges. In order to achieve the purpose, two methodologies were carried out. First is job analysis of the industrial designers who have worked in the small & medium manufacturing companies, second is survey for the opinions of professors in the junior colleges. Some results were as follows: 1. The period of junior college for industrial designers is 2 years according to present. But selectively 1 year of advanced course can be established. 2. The practice subjects same as computational formative techniques needed to product development have to be increased. In addition kinds of selection subjects same as foreign language, manufacturing process, new product information and consumer behavior investigation have to be extended. 3. The next subjects need to adjust the title, contents and hours. (1) The need of 3.D related subjects same as computer modeling, computer rendering, 3.D modeling was high. The use of computer is required to design presentation subjects. (2)The need of advertising and sale related subjects same as printing, merchandise, package, typography, photography was low, the need of presentation techniques of new product development was high. (3) The need of field practice, special lecture on practice and reading original texts related subjects was same as at present, but these are not attached importance to form. As the designers feel keenly the necessity of using foreign language, the need of language subject was high.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.135-135
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• 2018

천이금속 질화물 코팅은 우수한 기계적 특성들로 인해 공구 코팅으로 많이 사용 되어왔다. 그 중에서도 특히 Cr계 경질 코팅은 높은 경도와 낮은 표면조도, 우수한 마찰특성 등 뛰어난 기계적 특성을 나타내므로 공구 코팅으로의 적용 가능성이 크다. 그러나 최근 공구산업의 발전으로 인해 공구가 더욱 가혹한 환경에서 사용됨에 따라, 공구의 수명을 향상시키고 보호하기 위해 코팅의 높은 밀착력이 요구되고 있으며, 모재와 코팅 사이에 중간층을 합성함으로써 공구의 밀착력을 향상시키는 연구가 활발히 진행되고 있다. 이전 연구에서 모재/중간층/코팅간의 경도와 탄성계수 비율(H/E ratio)의 구배가 코팅의 밀착력에 큰 영향을 미치는 것으로 확인되었다. 그러므로, WC 모재와 Cr계 코팅의 중간값의 H/E ratio를 갖는 중간층의 합성을 통해 코팅의 밀착력을 향상시킬 수 있을 것으로 판단된다. 본 연구에서는, 코팅의 밀착력을 향상시키기 위해 다양한 중간층을 증착한 CrZrN, CrAlN 코팅을 비대칭 마그네트론 스퍼터링 장비를 이용하여 합성하였다. 모재로는 디스크 형상의 WC-6wt.%Co 시편을 사용하였고 Cr, Zr, Si, Al single 타겟을 이용하여 Cr, CrN, CrZrN, CrZrSiN 등의 중간층이 증착된 코팅을 합성했다. 코팅의 합금상, 경도 및 탄성계수, 미세조직 및 조성, 표면 조도을 확인하기 위해 X-ray diffractometer (XRD), Fischer scope, field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), atomic force microscopy를 사용하였고, 코팅의 밀착 특성을 분석하기 위해 scratch tester와 optical microscopy (OM)를 이용하였다. 코팅의 내열성을 확인하기 위해 코팅을 furnace에 넣어 공기중에서 500, 600, 700, 800, 900, $1,000^{\circ}C$로 30분 동안 annealing 한 후에 nano-indentation을 사용하여 경도를 측정하였다. CrZrN 및 CrAlN 코팅을 나노 인덴테이션으로 분석한 결과, 모든 코팅의 경도(33.4-35.8 GPa)와 탄성계수(384.1-391.4 GPa)는 중간층의 종류에 상관없이 비슷한 값을 보인 것으로 확인됐다. 그러나, 코팅의 마찰계수는 중간층의 종류에 따라 다른 값을 보였다. CrZrN 코팅의 경우 CrN 합금상 중간층을 갖을 때 가장 낮은 값을 보였으며, CrAlN 코팅의 경우 CrN/CrZrSiN 중간층을 증착하였을때 마찰계수는 0.34로 CrZrN 중간층을 증착하였을 때(0.41)에 비해 낮은 값을 보였다. 또한, 코팅의 마모율 및 마모폭도 비슷한 경향을 보인 것으로 보아, CrN/CrZrSiN 중간층을 합성한 CrAlN 코팅의 내마모성이 상대적으로 우수한 것으로 판단된다. 코팅의 밀착력의 경우도 마찰계수와 비슷한 경향을 보였다. 이것은 중간층의 H/E ratio가 코팅의 내마모성에 미치는 영향에 의한 결과로 사료된다. H/E ratio는 파단시의 최대 탄성 변형율로써, 모재/중간층/코팅의 H/E ratio 구배에 따라 코팅 내의 응력의 완화 정도가 변하게 된다. WC 모재 (H/E=0.040)와 CrAlN 코팅(H/E=0.089) 사이에서 CrN, CrZrSiN 중간층의 H/E ratio는 각각 0.076, 0.083으로 모재/중간층/코팅의 H/E ratio 구배가 점차 증가함을 확인 할 수 있었고, 일정 응력이 지속적으로 가해지면서 진행되는 마모시험중에 CrN과 CrZrSiN 중간층이 WC와 CrAlN 코팅 사이에서 코팅 내부의 응력구배를 완화시키는 역할을 함으로써 CrAlN 코팅의 내마모성이 향상된 것으로 판단된다. 모든 코팅을 열처리 후 경도 분석 결과, CrN/CrZrSiN 중간층을 증착한 CrAlN 코팅은 $1,000^{\circ}C$까지 약 28GPa의 높은 경도를 유지한 것으로 확인 되었고, 이는 CrZrSiN 중간층 내에 존재하는 SiNx 비정질상의 우수한 내산화성에 의한 결과로 판단된다.

• Korean Journal of Plant Resources
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• v.26 no.5
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• pp.589-596
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• 2013

Vaccinium bracteatum Thunb. is an evergreen plant that belongs to the Genus Vaccinium distributed in Korea, and its fruit has been used for food by the common people and thus has a high possibility of commercialization. Therefore, the habitat environment and individual characteristics of V. bracteatum in Jeju Island were investigated to obtain the basic data for commercialization and preservation. The results showed that V. bracteatum is mostly distributed on the southern slope of Mt. Halla at an altitude of 100 to 500 m. V. bracteatum that occurred in the quadrat were total 30 individuals, which had an average height of 6.0 m, an average DBH of 7.8 cm, and an average number of trunk of 4.3. As for the community structure of the habitat, the average percentage of vegetation cover for the tree layer was 36%, while that for the subtree layer was 78%, which emphasized the importance of the subtree layer. The total number of species that occurred in the quadrat was 76. For the tree layer, total 10 species occurred, which include 2 species of evergreen coniferous trees, 3 species of evergreen broad-leaved trees, and 5 species of deciduous broad-leaved trees. For the subtree layer, total 24 species occurred, which include 1 species of evergreen coniferous tree, 11 species of evergreen broad-leaved trees, and 10 species of deciduous broad-leaved trees. Among these, Eurya japonica Thunb. was the species with a high relative contribution, which threatened V. bracteatum For the shrub layer, 27 species occurred including Cinnamomum japonicum Siebold, and for the herbaceous layer, 64 species occurred including Ardisia crenata Sims. The similarity between the habitats of V. bracteatum was very low, and it did not prefer a characteristic community. The V. bracteatum community around Shinrei stream was distributed on the surrounding area adjacent to the slope of the stream rather than the slope. There were a lot of basins, but the branches, which did not receive sunlight, had withered. It is thought that V. bracteatum would decline if the forest formation continues.

• Journal of Biomedical Engineering Research
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• v.25 no.1
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• pp.11-19
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• 2004

Stage 1 sleep provides important information regarding interpretation of nocturnal polysomnography, particularly sleep onset. It is a short transition period from wakeful consciousness to sleep. Lack of prominent sleep events characterizing stage 1 sleep is a major obstacle in automatic sleep stage scoring. In this study, we attempted to utilize simultaneous EEC and EOG processing and analyses to detect stage 1 sleep automatically. Relative powers of the alpha waves and the theta waves were calculated from spectral estimation. Either the relative power of alpha waves less than 50％ or the relative power of theta waves more than 23％ was regarded as stage 1 sleep. SEM (slow eye movement) was defined as the duration of both eye movement ranging from 1.5 to 4 seconds and regarded also as stage 1 sleep. If one of these three criteria was met, the epoch was regarded as stage 1 sleep. Results f ere compared to the manual rating results done by two polysomnography experts. Total of 169 epochs was analyzed. Agreement rate for stage 1 sleep between automatic detection and manual scoring was 79.3％ and Cohen's Kappa was 0.586 (p＜0.01). A significant portion (32％) of automatically detected stage 1 sleep included SEM. Generally, digitally-scored sleep s1aging shows the accuracy up to 70％. Considering potential difficulties in stage 1 sleep scoring, the accuracy of 79.3％ in this study seems to be robust enough. Simultaneous analysis of EOG provides differential value to the present study from previous oneswhich mainly depended on EEG analysis. The issue of close relationship between SEM and stage 1 sleep raised by Kinnariet at. remains to be a valid one in this study.

• The Transactions of the Korea Information Processing Society
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• v.1 no.3
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• pp.367-379
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• 1994

This paper describes scheduling algorithms of the UNIX operating system and shows an analytical approach to approximate the average conditional response time for a process in the UNIX operating system. The average conditional response time is the average time between the submittal of a process requiring a certain amount of the CPU time and the completion of the process. The process scheduling algorithms in thr UNIX system are based on the priority service disciplines. That is, the behavior of a process is governed by the UNIX process schuduling algorithms that (ⅰ) the time-shared computer usage is obtained by allotting each request a quantum until it completes its required CPU time, (ⅱ) the nonpreemptive switching in system mode and the preemptive switching in user mode are applied to determine the quantum, (ⅲ) the first-come-first-serve discipline is applied within the same priority level, and (ⅳ) after completing an allotted quantum the process is placed at the end of either the runnable queue corresponding to its priority or the disk queue where it sleeps. These process scheduling algorithms create the round-robin effect in user mode. Using the round-robin effect and the preemptive switching, we approximate a process delay in user mode. Using the nonpreemptive switching, we approximate a process delay in system mode. We also consider a process delay due to the disk input and output operations. The average conditional response time is then obtained by approximating the total process delay. The results show an excellent response time for the processes requiring system time at the expense of the processes requiring user time.

• Geophysics and Geophysical Exploration
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• v.11 no.2
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• pp.127-136
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• 2008

To identify the potential area of gas hydrate in the Ulleung Basin, 2-D and 3-D seismic surveys using R/V Tamhae II were conducted in 2005 and 2006. Seismic survey equipment consisted of navigation system, recording system, streamer cable and air-gun source. For reliable velocity analysis in a deep sea area where water depths are mostly greater than 1,000 m and the target depth is up to about 500 msec interval below the seafloor, 3-km-long streamer and 1,035 $in^3$ tuned air-gun array were used. During the survey, a suite of quality control operations including source signature analysis, 2-D brute stack, RMS noise analysis and FK analysis were performed. The source signature was calculated to verify its conformity to quality specification and the gun dropout test was carried out to examine signature changes due to a single air gun's failure. From the online quality analysis, we could conclude that the overall data quality was very good even though some seismic data were affected by swell noise, parity error, spike noise and current rip noise. Especially, by checking the result of data quality enhancement using FK filtering and missing trace restoration technique for the 3-D seismic data inevitably contaminated with current rip noises, the acquired data were accepted and the field survey could be conducted continuously. Even in survey areas where the acquired data would be unsuitable for quality specification, the marine seismic survey efficiency could be improved by showing the possibility of noise suppression through onboard data processing.

• Land and Housing Review
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• v.2 no.4
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• pp.367-377
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• 2011

This paper investigates the determination factors' variation of real estate price after sub-prime financial crisis, in korea, using a VAR model. The model includes land price, housing price, housing rent (Jensei) price, which time period is from 2000:1Q to 2011:2Q and uses interest rate, real GDP, consumer price index, KOSPI, the number of housing construction, the amount of land sales and practices to impulse response and variance decomposition analysis. Data cover two sub-periods and divided by 2008:3Q that occurred the sub-prime crisis; one is a period of 2000:1Q to 2008:3Q, the other is based a period of 2000:1Q to 2011:2Q. As a result, Comparing sub-prime crisis before and after, land price come out that the influence of real GDP is expanding, but current interest rate's variation is weaken due to the stagnation of current economic status and housing construction market. Housing price is few influenced to interest rate and real GDP, but it is influenced its own variation or Jensei price's variation. According to the Jensei price's rapidly increasing in nowadays, housing price might be increasing a rising possibility. Jensei price is also weaken the influence of all economic index, housing price, comparing before sub-prime financial crisis and it is influenced its own variation the same housing price. As you know, real estate price is weakened market basic value factors such as, interest rate, real GDP, because it is influenced exogenous economic factors such as population structural changes. Economic participators, economic officials, consumer, construction supplyers need to access an accurate observation about current real estate market and economic status.

• Korean Journal of Remote Sensing
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• v.25 no.5
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• pp.423-434
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• 2009

The Arctic environment is sensitive to change of sea-ice distribution. The increase and decrease of sea ice work to an index of globe warming progress. In order to predict the progress of hereafter earth global warming, continuous monitoring regarding a change of the sea ice area in the Arctic should be performed. The remote sensing based on an artificial satellite is most effective on the North Pole. The sea ice observation using a passive microwave sensor has been continued from 1970's. The determination of sea ice extent and ice type is one of the great successes of the passive microwave imagers. In this paper, to investigate the seasonal and inter-annual variation of sea-ice distribution we used here the sea ice data from July 2002 to May 2009 around the Arctic within $60^{\circ}N$ for the AMSR-E 12.5km sea-ice concentration, a passive microwave sensor. From an early analysis of these data, the arctic sea-ice extent has been steadily decreasing at a rate of about 3.1%, accounting for about $2{\times}10^5\;km^2$, which was calculated for the sea-ice cover reaching its minimum extent at the end of each summer. It is also revealed that this trend corresponds to a decline in the multi-year ice that is affected mainly by summer sea surface and air temperature increases. The extent of younger and thinner (first-year) ice decreased to the 2007 minimum, but rapidly recovered in 2008 and 2009 due to the dramatic loss in 2007. Seasonal variations of the sea-ice extent show significant year-to-year variation in the seasons of January-March in the Barents and Labrador seas and August-October in the region from the East Siberian and Chukchi seas to the North Pole. The spatial distribution of multi-year ice (7-year old) indicates that the perennial ice fraction has rapidly shrunk recently out of the East Siberian, Laptev, and Kara seas to the high region of the Arctic within the last seven years and the Northeast Passage could become open year-round in near future.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.3
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• pp.105-112
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• 2003

Effects of magnesium sulfate ($MgSO_4$) and magnesium hydroxide $[Mg(OH)_2]$, which have different chemical characteristics, on soil pH, electrical conductivity (EC), and exchangeable cation distributions were investigated. Using plastic columns packed with a loam soil, the two Mg-fertilizers were treated at the rate of $300kg\;MgO\;ha^{-1}$ and water was applied on the soil surface four times at every 7 days. Soil samples were taken at 5, 10, 15, and 20 cm depth after 7 days of each water application. Magnesium hydroxide could increase soil pH, but due to the low solubility of $Mg(OH)_2$, the effect on pH was limited on the surface soil. Soil pH was lowered in the $MgSO_4$ treatment and the effect was found through the 20 cm depth. Since the pH decrease in $MgSO_4$ treated soil was due to the salts from $MgSO_4$, after leaching of most salts from the investigated soil depth pH was not significantly different from that of non-treated soil. Soil EC was increased in $MgSO_4$ treatment through the soil depth, but in $Mg(OH)_2$ treatment EC was slightly increased only at the surface layer. Exchangeable Mg was increased in both of the treatments at surface layer after the first water application. In $Mg(OH)_2$ treatment, the increase of exchangeable Mg was found only at 5 cm depth through the experiment, but leaching down of Mg in the $MgSO_4$ treatment was very apparent. High concentration of Mg in the $MgSO_4$ treated soil could effectively replace exchangeable Ca through the investigated soil depth, but the effect of $Mg(OH)_2$ on exchangeable Ca was not significant.