• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권1호
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• pp.5-25
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• 2009

In recent years the popularity of multi-hop wireless networks has been growing. Its flexible topology and abundant routing path enables many types of applications. However, the lack of a centralized controller often makes it difficult to design a reliable service in multi-hop wireless networks. While packet routing has been the center of attention for decades, recent research focuses on data discovery such as file sharing in multi-hop wireless networks. Although there are many peer-to-peer lookup (P2P-lookup) schemes for wired networks, they have inherent limitations for multi-hop wireless networks. First, a wired P2P-lookup builds a search structure on the overlay network and disregards the underlying topology. Second, the performance guarantee often relies on specific topology models such as random graphs, which do not apply to multi-hop wireless networks. Past studies on wireless P2P-lookup either combined existing solutions with known routing algorithms or proposed tree-based routing, which is prone to traffic congestion. In this paper, we present two wireless P2P-lookup schemes that strictly build a topology-dependent structure. We first propose the Ring Interval Graph Search (RIGS) that constructs a DHT only through direct connections between the nodes. We then propose the ValleyWalk, a loosely-structured scheme that requires simple local hints for query routing. Packet-level simulations showed that RIGS can find the target with near-shortest search length and ValleyWalk can find the target with near-shortest search length when there is at least 5% object replication. We also provide an analytic bound on the search length of ValleyWalk.

• Environmental Engineering Research
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• 제22권1호
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• pp.19-30
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• 2017

Direct catalysis of vapors from vacuum pyrolysis of biomass was performed on MCM-41 to investigate the effects of operating parameters including catalyzing temperature, catalyzing bed height and system pressure on the organic yields. Optimization of organic phase yield was further conducted by employing response surface methodology. The statistical analysis showed that operating parameters have significant effects on the organic phase yield. The organic phase yield first increases and then decreases as catalyzing temperature and catalyzing bed height increase, and decreases as system pressure increases. The optimal conditions for the maximum organic phase yield were obtained at catalyzing temperature of $502.7^{\circ}C$, catalyzing bed height of 2.74 cm and system pressure of 6.83 kPa, the organic phase yield amounts to 15.84% which is quite close to the predicted value 16.19%. The H/C, O/C molar ratios (dry basis), density, pH value, kinematic viscosity and high heat value of the organic phase obtained at optimal conditions were 1.287, 0.174, $0.98g/cm^3$, 5.12, $5.87mm^2/s$ and 33.08 MJ/kg, respectively. Organic product compositions were examined using gas chromatography/mass spectrometry and the analysis showed that the content of oxygenated aromatics in organic phase had decreased and hydrocarbons had increased, and the hydrocarbons in organic phase were mainly aliphatic hydrocarbons. Besides, thermo-gravimetric analysis of the MCM-41 zeolite was conducted within air atmosphere and the results showed that when the catalyst continuously works over 100 min, the index of physicochemical properties of bio-oil decreases gradually from 1.15 to 0.45, suggesting that the refined bio-oil significantly deteriorates. Meanwhile, the coke deposition of catalyst increases from 4.97% to 14.81%, which suggests that the catalytic activity significantly decreases till the catalyst completely looses its activity.

• 수산해양교육연구
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• 제27권6호
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• pp.1619-1627
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• 2015

The purpose of this study was to examine the relationship between the safety awareness and safety practice behavior of adult learners who participated in "civic safety culture college" was held in Changwon city. We carried out a questionnaire survey that was targeted at 150 citizens, but 132 citizens were included finally. Data collected were analyzed with SPSS 21.0 statistical program. Analysis methods were t-test, one way ANOVA, Scheffe test, Pearsons correlation coefficient, and multiple linear regression. The results were as follows. First, safety awareness point was an average of 4.17 point which was higher levels. Area showing the highest safety awareness was fire safety. Safety practice behavior point was an over intermediate level of an average of 3.58 point. Second, safety practice behavior had statistically significant difference according to sex(t=2.58, p=.01), education(t=-2.57, p=.01), job(t=-1.96, p=.05), housing(t=3.65, p<.001). Third, there was a positive correlation between home safety awareness(r=.28, p<.001), traffic safety awareness(r=.37, p<.001), fire safety awareness(r=.37, p<.001), emergency care awareness(r=.45, p<.001) and safety practice behavior. Fourth, safety practice behavior was related to the emergency care awareness(${\beta}$=.34, p=.002), this factor accounted for 19.5% of the variability of the safety practice behavior. These results are expected to be very important baseline data for many different businesses and program development for strengthening of safety awareness and spreading of safety culture in Changwon city.

• Journal of Chest Surgery
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• 제46권2호
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• pp.130-134
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• 2013

Background: Rib fractures are the most common type of thoracic trauma and cause other complications. We explored the risk factors for pneumonia in patients with multiple rib fractures. Materials and Methods: Four hundred and eighteen patients who visited our hospital with multiple rib fractures between January 2002 and December 2008 were retrospectively reviewed. Chest X-rays and chest computed tomography were used to identify injury severity. Patients with only a single rib fracture or who were transferred to another hospital within 2 days were excluded. Results: There were 327 male patients (78%), and the median age was 53 years. The etiologies of the patients' trauma included traffic accidents in 164 cases (39%), falls in 78 cases (19%), slipping and falling in 90 (22%), pedestrian accidents in 30 (7%), industrial accidents in 41 (10%), and assault in 15 (4%). The median number of rib fractures was 4.8. Pulmonary complications including flail chest (2.3%), lung contusion (22%), hemothorax (62%), pneumothorax (31%), and hemopneumothorax (20%) occurred. Chest tubes were inserted into the thoracic cavity in 216 cases (52%), and the median duration of chest tube insertion was 10.26 days. The Injury Severity Score (ISS) and rib score had a median of 15.27 and 6.9, respectively. Pneumonia occurred in 18 cases (4.3%). Of the total cases, 33% of the cases were managed in the intensive care unit (ICU), and the median duration of stay in the ICU was 7.74 days. Antibiotics were administered in 399 patients (95%) for a median of 10.53 days. Antibiotics were used for more than 6 days in 284 patients (68%). The factors affecting pneumonia in patients with multiple rib fractures in multivariate analysis included age (p=0.004), ISS (p<0.001), and rib score (p=0.038). The use of antibiotics was not associated with the occurrence of pneumonia (p=0.28). In-hospital mortality was 5.3% (n=22). Conclusion: The factors affecting risk of pneumonia in patients with multiple rib fractures included age (p=0.004), ISS (p<0.001), and rib score (p=0.038). Elderly patients with multiple traumas have a high risk of pneumonia and should be treated accordingly.

• 척추신경추나의학회지
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• 제4권2호
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• pp.47-60
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• 2009

Objectives : The purpose of this study is to investigate the effect of chuna treatment on cervical sprain caused by traffic accident in early stage. Methods : This study carried out on 20 patients who have received hospital treatment in Daejeon Univ. cheonan Oriental Hospital. Non-chuna group got acupunture-therapy, herbal medication, physical therapy and Chuna group got chuna treatment besides. We measured Heart Rate Variability(HRV) and Visual Analog Scale(VAS) on 2nd, 4th day. Results : After being treated by our methods, Chuna Group showed the inclination to balance the sympathetic and parasympathetic nerve. In chuna group, an autonomic nerve activity showed the inclination to increase. But there were no significant difference between both groups. Chuna group's VAS were significantly decreased(p=0.043). Conclusions : The results suggest that Chuna treatment help traffic accident patients in early stage to reduce pain. Refer to autonomic nerve system, chuna treatment seem to do positive effect but Further long tenn study in a large scale is needed.

• 환경정책연구
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• 제7권3호
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• pp.141-160
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• 2008

본 연구는 속리산 국립공원에서 쌍곡계곡 지역과 법주사 지역 내에 위치한 지역 중에서 인간의 의한 교란이 가장 큰 도로개설지역, 교란이 중간 정도인 등산로지역 그리고 간섭이 거의 없는 출입통제지역을 선택하여 산림생태계에서 인간의 교란 정도에 따른 조류군집의 차이를 연구하였다. 번식기와 비번식기의 조사(n=12)에서 조류의 종수와 개체수, 종다양도 및 밀도에서는 세 지역 사이에 유의적인 차이가 나타나지 않았다. 그러나 번식기의 조사(n=9)에서는 조류의 종수(Kruskal Wallis, $x^2$=10.32, p=0.006)와 개체수(Kruskal Wallis, $x^2$=7.118, p=0.028) 및 종다양도(Kruskal Wallis, $x^2$=9.847, p=0.007)가 인간에 의한 교란이 중간정도인 등산로 지역에서 가장 높게 나타났다. 그러나 번식기 조류 군집의 영소 및 취식 길드 분석에서는 세 지역 사이에 영소 및 취식 길드 분포비율은 차이가 나타나지 않았다. 영소길드는 세 지역 모두 나무구멍 영소길드가 가장 높았고, 취식길드는 수관층 취식길드가 가장 높게 나타났다.

• 보건교육건강증진학회지
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• 제19권1호
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• pp.87-107
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• 2002

Recently, the industrialized world is suffering from accidents referring from the lack of safety consciousness. According to Korean Safety Regulation Department(1996), students at junior high schools are mostly involved in safety accidents, and this is due to lack of safety consciousness. To prevent these accidents, we need to have safety consciousness and attitude. To make junior high school students who are mostly affected in these accidents act safely, they need to know their level of safety consciousness. The purpose of this study is to develop a guideline of measuring the scale of safety consciousness and analyze the relationship between safety education, accident experiences and safety consciousness. This study is based on a survey of 708 junior high students in Seoul, which was carried out from 12 November, 2001 to 21 November, 2001. 1. The main fields of safety consciousness are home safety, school safety, fire safety, emergency management based on documents. Home safety is again divided into facility safety and livelihood safety, school safety is divided into facility safety, livelihood safety and laboratory safety, traffic safety is divided into pedestrian safety, bicycling safety and public transportation safety, fire safety divided into prevention and escaping during fire breakouts, emergency management safety is divided into general principles and escaping during emergency situations. 2. The primary safety consciousness scale was made according to every field of safety consciousness. A preliminary examination based on the scale and a study of reliance and the factors was held. Based on these results, 27 questions which were concerned to be impairing reliability or lacking in factor were deleted on the secondary safety consciousness scale development The secondary safety consciousness scale which constituted of 73 questions was put into another preliminary study and after analyzing reliability and the factors, 12 questions of low reliabilities were deleted and with these results, the third scale were made consisting of 61 questions. 3. A study based on the third safety scale which is made of 61 questions, were held and with a analysis of the reliability and factors made, the relationship between safety education, accident experience and safety mind were examined. (1) The study of reliability and factors show that Cronbach's coefficient in home safety fields is .7598, in school safety .7924, in traffic safety .8306, in emergency treatment .7775, in fire safety .7247. The questions indicating low reliability were deleted. The factor analysis revealed that home safety is converged on facility safety and livelihood safety. But one question was deleted because it showed incongruence of validity. School safety was converged on facility safety, livelihood safety and laboratory safety. But 2 questions showed incongruence of validity and these were deleted. Traffic safety fields were converged on pedestrian safety, bicycle safety and public transportation safety. One question showing incongruence of validity was deleted. Emergency treatment fields converged on general principles and acting in emergency situations and three questions showing incongruence of validity were deleted. Fire safety was converged on prevention and acting in fire breakouts. Totally, eight questions were removed and the final scale were consisted of 53 questions (2) The 3/sup rd/ grade students scored higher average safety mind scales than 1st graders(p〈.05). And students who had high scores at school tend to have a higher scale than those who do not(p〈.001). (3) Average scale of students who had experience in safety education were higher(p〈.001). Students who had previously been involved in home safety accidents had a low score(p〈.001). This was same to students with experience in school safety accidents(p〈.001). Students with traffic safety accidents and fire safety accidents tend to have a lower scale too(p〈.05, p〈.001).

• Journal of Communications and Networks
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• 제15권2호
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• pp.142-152
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• 2013

The network mobility basic support (NEMO BS) protocol has been investigated to provide Internet connectivity for a group of nodes, which is suitable for intelligent transportation systems (ITS) applications. NEMO BS often increases the traffic load and handover latency because it is designed on the basis of mobile Internet protocol version 6 (MIPv6). Therefore, schemes combining proxy MIPv6 with NEMO (P-NEMO) have emerged to solve these problems. However, these schemes still suffer from packet loss and long handover latency during handover. Fast P-NEMO (FP-NEMO) has emerged to prevent these problems. Although the FP-NEMO accelerates handover, it can cause a serious tunneling burden between the mobile access gateways (MAGs) during handover. This problem becomes more critical as the traffic between the MAGs increases. Therefore, we propose a scheme for designing an improved FP-NEMO (IFP-NEMO) to eliminate the tunneling burden by registering a new address in advance. When the registration is completed before the layer 2 handover, the packets are forwarded to the new MAG directly and thereby the IFP-NEMO avoids the use of the tunnel between the MAGs during handover. For the evaluation of the performance of the IFP-NEMO compared with the FP-NEMO, we develop an analytical framework for fast handovers on the basis of P-NEMO. Finally, we demonstrate that the IFP-NEMO outperforms the FP-NEMO through numerical results.

• Wind and Structures
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• 제35권4호
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• pp.269-285
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• 2022

The pressure-mitigating effects of a high-speed train passing through a tunnel with a partially reduced cross-section are investigated via the numerical approach. A compressible, three-dimensional RNG k-ε turbulence model and a hybrid mesh strategy are adopted to reproduce that event, which is validated by the moving model test. Three step-like tunnel forms and two additional transitions at the tunnel junction are proposed and their aerodynamic performance is compared and scrutinized with a constant cross-sectional tunnel as the benchmark. The results show that the tunnel step is unrelated to the pressure mitigation effects since the case of a double-step tunnel has no advantage in comparison to a single-step tunnel, but the excavated volume is an essential matter. The pressure peaks are reduced at different levels along with the increase of the excavated earth volume and the peaks are either fitted with power or logarithmic function relationships. In addition, the Arc and Oblique-transitions have very limited gaps, and their pressure curves are identical to each other, whereas the Rec-transition leads to relatively lower pressure peaks in C_Pmax, C_Pmin, and ΔC_P, with 5.2%, 4.0%, and 4.1% relieved compared with Oblique-transition. This study could provide guidance for the design of the novel railway tunnel.

• Journal of applied mathematics & informatics
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• 제22권1_2호
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• pp.273-283
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• 2006

We obtain an asymptotic behavior of the loss probability for the GI/PH/1/K queue as K tends to infinity when the traffic intensity p is strictly less than one. It is shown that the loss probability tends to 0 at a geometric rate and that the decay rate is related to the matrix generating function describing the service completions during an interarrival time.