• 정보처리학회논문지:컴퓨터 및 통신 시스템
• /
• 제3권2호
• /
• pp.47-56
• /
• 2014

인터넷을 기반으로 하는 다양한 서비스 및 응용의 등장과 무선 디바이스의 보급은 인터넷 트래픽을 급격하게 증가시켰다. 인터넷 트래픽의 급격한 증가로 한정적인 네트워크 자원을 효율적으로 사용하기 위해 인터넷 트래픽 분석의 중요성이 증가하고 있다. 하지만 트래픽 분석 방법론에 비해 분석 결과를 체계적으로 관리하는 분류 체계에 대한 연구는 이루어지지 않고 있다. 본 논문에서는 다각적이고 계층적인 트래픽 분석을 위한 분류 체계를 제안한다. 제안하는 분류 체계는 서비스, 응용, 프로토콜, 기준의 4가지 분류 기준을 사용하여 다각적으로 분석이 가능하며, 분류 기준 별로 계층화된 속성을 가지고 있어 결과의 통합화 및 세분화가 가능하다. 논문에서는 제안한 분류 기준을 실제 학내 망에 적용하여 분석함으로 분류 체계의 장점과 활용성을 보인다.

• Journal of Dental Anesthesia and Pain Medicine
• /
• 제16권3호
• /
• pp.199-202
• /
• 2016

Background: The aim of this study was to provide insight on dental fear amongst schoolchildren and evaluate the association between caries experience and fear of dental procedures. Methods: A sample size of 250 students (both sexes) of ages 10-14 years were enrolled in the study. Before dental examination, each participant was informed about the study and given the Children's Fear Survey Schedule - Dental Subscale (CFSS-DS) questionnaire. Children who scored greater than 38 were included in the 'with dental fear' group and those who scored less than 38 were assigned to the 'without dental fear' group. All oral check-ups were carried out on the school premises according to WHO criteria. Results: There were 105 children (42%) who experienced dental fear. As CFSS-DS scores increased, scores on the Decayed, Missing and Filled Surfaces Index (DMFS) also increased. Scores were highest on "injections" followed by "dentist drill" and "feeling of choking". Children were significantly less anxious about items of dental treatment if they had experienced that particular form of treatment. Female participants were found to be more dentally anxious than the male participants. Conclusions: The data revealed dental fear in 10-14 years old children and showed that dental fear scores decreased with increase in age and experience.

• Geomechanics and Engineering
• /
• 제13권6호
• /
• pp.997-1010
• /
• 2017

The black box model is a relatively new option for nonlinear dynamic system identification. It can be used for prediction problems just based on analyzing the input and output data without considering the changes of the internal structure. In this paper, a black box model was presented to solve unconstrained overlying strata movement problems in coal mine production. Based on the black box theory, the overlying strata regional system was viewed as a "black box", and the black box model on overburden strata movement was established. Then, the rock mechanical properties and the mining thickness and mined-out section area were selected as the subject and object respectively, and the influences of coal mining on the overburden regional system were discussed. Finally, a corrected method for height prediction of the fractured zone was obtained. According to actual mine geological conditions, the measured geological data were introduced into the black box model of overlying strata movement for height calculation, and the fractured zone height was determined as 40.36 m, which was comparable to the actual height value (43.91 m) of the fractured zone detected by Double-block Leak Hunting in Drill. By comparing the calculation result and actual surface subsidence value, it can be concluded that the proposed model is adaptable for height prediction of the fractured zone.

• 한국기계기술학회지
• /
• 제13권4호
• /
• pp.1-7
• /
• 2011

The paper concerns numerical study of fully developed laminar flow of a Newtonian water and non-Newtonian fluids, 0.2% aqueous of sodium carboxymethyl cellulose(CMC) solution in eccentric annuli with combined bulk axial flow and inner cylinder rotation. Pressure losses and skin friction coefficients have been measured when the inner cylinder rotates at the speed of 0~200 rpm. A numerical analysis considered mainly the effects of annular eccentricity and inner cylinder rotation. The present analysis has demonstrated the importance of the drill pipe rotation and eccentricity. In eccentricity of 0.7 of a Newtonian water, the flow field is recirculation dominated and unexpected behavior is observed. it generates a strong rotation directed layer, that two opposing effects act to create two local peaks of the axial velocity. The influences of rotation, radius ratio and working fluid on the annular flow field are investigated.

• Journal of Korean Neurosurgical Society
• /
• 제62권2호
• /
• pp.144-152
• /
• 2019

Treatment of chronic subdural hematoma (CSDH) is relatively straightforward, however, there is still some debate regarding the best strategy for treatment. The most practical recommendations of up to date were identified by a review of literature. The author reviewed the literature on CSDH management from the past to now to identify the best methods. Till 1970s, craniotomy was the most commonly used method. Burr hole (BH) became the most preferred method from 1980s. In 1977, twist drill (TD) craniostomy was introduced. Closed system drainage after a BH or a TD became the most frequently used surgical method. Although nonsurgical treatment is often successful, trephination has more advantages, such as rapid resolution of the symptoms and short period of hospitalization. Nonsurgical treatment is possible in asymptomatic patients with a small CSDH. For the symptomatic patients with CSDH, trephination is the treatment of choice, either by BH or TD. In gray zone between surgery and medical treatment, shared decision making can be an ideal approach. For the recurrent CSDHs, repeated trephination is still effective for patients with a low risk of recurrence. If the risk of recurrence is high, additional management would be helpful. For the refractory CSDHs, it is necessary to obliterate the subdural space.

• Geomechanics and Engineering
• /
• 제19권1호
• /
• pp.93-104
• /
• 2019

Anomalies and/or fractured grounds not detected by the surface geophysical and geological survey performed during design stage may cause significant problems during tunnel excavation. Many studies on prediction methods of the ground condition ahead of the tunnel face have been conducted and applied in tunneling construction sites, such as tunnel seismic profiling and probe drilling. However, most such applications have focused on the drill and blast tunneling method. Few studies have been conducted for mechanized tunneling because of the limitation in the available space to perform prediction tests. This study aims to predict the ground condition ahead of the tunnel face in TBM tunneling by using an electrical resistivity tomography survey. It compared the characteristics of each electrode array and performed an investigation on in-situ tunnel boring machine TBM construction site environments. Numerical simulations for each electrode array were performed, to determine the proper electrode array to predict anomalies ahead of the tunnel face. The results showed that the modified dipole-dipole array is, compared to other arrays, the best for predicting the location and condition of an anomaly. As the borehole becomes longer, the measured data increase accordingly. Therefore, longer boreholes allow a more accurate prediction of the location and status of anomalies and complex grounds.

• 대한조선학회논문집
• /
• 제56권3호
• /
• pp.251-262
• /
• 2019

This paper is about design concept and simplified analysis method against dropped object events. The ships and offshore structures are exposed to various types of dropped object accidents such as laydown area struck by drill collar and topside deck hit by food container during their lifetime. Mitigation can be accomplished by proper facility layout and designing structures to safely absorb energy from accidental loads. It shall be designed to avoid loss of life, environmental pollution and loss of assets. Impact loads can lead to structural global collapse of the main structure or punching of a local barrier type structure with potential to escalate directly or indirectly to a global collapse of the structure. This study provides the background information on the issue of dropped object of the shipyard and also focuses on structural assessment of the local individual component such as deck plate, stiffener and web/girder by using simplified analysis method. The results of the simplified analysis method were compared with numerical results using non-linear finite element simulation.

• 한국기계가공학회지
• /
• 제21권9호
• /
• pp.12-20
• /
• 2022

Delamination and burr defects are important problems in drilling fiber reinforced plastics. A method for measuring FRP drilling defects has been studied. Delamination and burr factors were defined as the relative length or area. Using these factors, the effects of tool shape and drilling conditions on delamination and burr were studied. In this study, the defects that occur when drilling a glass-carbon fiber hybrid composite were compared in terms of three factors. In the glass-carbon fiber hybrid composite, the effects of the feed rate and tool point angle on the delamination and burr factors were similar to those in previous studies. The diameter of the tool did not affect the defect factor. A circular burr was generated in a drill tool with a point angle of 184°, and a relatively small deburring factor was observed compared with a tool with a point angle of 140°.

• Geomechanics and Engineering
• /
• 제29권1호
• /
• pp.65-77
• /
• 2022

Determination of strength properties of intact rock using artificial cores has been considered in recent years. In this study, some relationships for estimating the static properties of dolomudstone cores of the Asmari reservoir were presented using artificial cores prepared from cuttings of two wells, southwest of Iran. For this purpose, first natural cuttings (NC) and 33 cores including dolomite limestone (dolomudstone), anhydrite and anhydrite dolomite were prepared between depths of 1714 and 2208 meters. Petrographic, physical, mechanical and dynamic tests were performed on cores, NC and artificial cuttings (AC) which was prepared from the residuals of dolomudstone cores. For preparing the artificial cores, the average porosity of the dolomudstone cores was considered and determined using four methods. Artificial and natural cuttings were classified as dolomite limestone and dolomite limestone to calcareous dolomite, respectively. Using ordinary Portland cement (OPC), water, AC and NC artificial cores were prepared. Results of evaluating the proposed relationships using statistical criteria showed that the static properties of the artificial cores can be used to predict the static properties of the dolomudstone cores.

• 한국작물학회지
• /
• 제27권4호
• /
• pp.452-461
• /
• 1982

Average yield of wheat and barley cultivars has been increased 3 percent every year by varietal improvement. The major characteristic changes of those improved cultivars were the early maturing and lodging resistance using dwarf genes, 70-90cm of culm length appearances, under the heavy fertilizer application. Looking back the cultural practices of wheat and barley for the last 20 years, the introduction of early maturing and lodging resistance cultivars around 1970 brought the changes of seeding rate from 65kg to 130- 200kg per hector and the tillering increased by heavy fertilizer. The utilization of livestock and man power for preparation of seedbed were gradually disappeared by increasing agricultural mechanization. The narrow-spaced seeding $(40cm {\times} l8cm)$ and drill seeding $(20cm {\times} 5cm)$ in upland, broadcasting or drilling on high ridge $(120cm {\times} 90cm)$ with the power-toller and whole area broadcasting in paddy field were improved as the main cultural method. The use of agricultural machineries reduced the labour consumption of 940 man hours to 180 man hours per hector from seeding to harvest.