• Journal of computational fluids engineering
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• v.20 no.4
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• pp.109-115
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• 2015

In this study, the Stokes flow in the microchannel is analysed where the semicircular protuberances with constant spacing are attached on the upper and lower walls with staggered arrangement. For the low Reynolds number flow in microchannel, Stokes approximation is used and the periodicity and symmetry of the flow are considered to determine the stream function and pressure distribution in the flow field by using the method of least squared error. As results, the streamline patterns and pressure distributions in the flow field are shown for some specific values of the size and spacing of the protuberances, and shear stress distributions on the surface of semicircular protuberances are plotted. Especially, for an important physical property, the average pressure gradient along the microchannel is obtained and compared with that for the case of in-phase arrangement of the upper and lower protuberances. And, for the small clearance between the protuberances of upper and lower walls or between the protuberances and the opposite wall, the average pressure gradient is derived from the lubrication theory and compared with that of the present study.

• The KIPS Transactions:PartB
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• v.16B no.5
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• pp.427-434
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• 2009

With the rapid evolution of the Internet and mobile environments, text including spelling errors such as newly-coined words and abbreviated words are widely used. These spelling errors make it difficult to develop NLP (natural language processing) applications because they decrease the readability of texts. To resolve this problem, we propose a spelling error correction model using a spelling error correction dictionary and a newspaper corpus. The proposed model has the advantage that the cost of data construction are not high because it uses a newspaper corpus, which we can easily obtain, as a training corpus. In addition, the proposed model has an advantage that additional external modules such as a morphological analyzer and a word-spacing error correction system are not required because it uses a simple string matching method based on a correction dictionary. In the experiments with a newspaper corpus and a short message corpus collected from real mobile phones, the proposed model has been shown good performances (a miss-correction rate of 7.3%, a F1-measure of 97.3%, and a false positive rate of 1.1%) in the various evaluation measures.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.508-519
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• 2021

In this study, a model was developed to predict the peak particle velocity (PPV) that affects people and the surrounding environment during blasting. Four machine learning models using the k-nearest neighbors (kNN), classification and regression tree (CART), support vector regression (SVR), and particle swarm optimization (PSO)-SVR algorithms were developed and compared with each other to predict the PPV. Mt. Yogmang located in Changwon-si, Gyeongsangnam-do was selected as a study area, and 1048 blasting data were acquired to train the machine learning models. The blasting data consisted of hole length, burden, spacing, maximum charge per delay, powder factor, number of holes, ratio of emulsion, monitoring distance and PPV. To evaluate the performance of the trained models, the mean absolute error (MAE), mean square error (MSE), and root mean square error (RMSE) were used. The PSO-SVR model showed superior performance with MAE, MSE and RMSE of 0.0348, 0.0021 and 0.0458, respectively. Finally, a method was proposed to predict the degree of influence on the surrounding environment using the developed machine learning models.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6D
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• pp.931-936
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• 2008

Surveying by using terrestrial LiDAR(Light Detection And Ranging) is more rapid than by using total station which enables tunnel section profile surveying to be done in suitable time and minimize centerline error, occurrence of overcut and undercut. Therefore, utilization of terrestrial LiDAR has increased more and more in section profile survey and measurement field Moreover, studies of terrestrial LiDAR for accurate and efficient utilization is now ongoing vigorously. Average end area formula, which was generally used to calculate overcut and undercut, was compared with existing methods such as total station survey and photogrammetry. However, there are no criteria of spacing distance for calculating overcut and undercut through terrestrial LiDAR surveying which can acquire 3D information of whole tunnel. This research performed reverse engineering to decide optimal spacing distance when surveying tunnel section profile by comparing whole tunnel volume and tunnel volume in difference spacing distance. This result was utilized to produce CAD drawing for the test tunnel site where there is no design drawings. In addition to this, efficiency of LiDAR and accuracy of CAD drawing was compared with targetless total station surveying of tunnel section profile. Finally, error analysis of target coordinate's accuracy and incidence angle was done in order to verify the accuracy of terrestrial LiDAR technology.

• Journal of KIISE:Software and Applications
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• v.35 no.6
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• pp.386-391
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• 2008

Some spoken word errors that violate grammatical or writing rules occurs frequently in communication environments like mobile phone and messenger. These unexpected errors cause a problem in a language processing system for many applications like speech recognition, text-to-speech translation, and so on. In this paper, we proposed and implemented an automatic correction system of ill-formed words and word spacing errors in SMS sentences that has been the major errors of poor accuracy. We experimented three methods of constructing the word correction dictionary and evaluated the results of those methods. They are (1) manual construction of error words from the vocabulary list of ill-formed communication languages, (2) automatic construction of error dictionary from the manually constructed corpus, and (3) context-dependent method of automatic construction of error dictionary.

• Korean Journal of Agricultural Science
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• v.24 no.2
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• pp.145-155
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• 1997

The large scaled field test by prefabricated vertical drains was performed to evaluate the superiority of vertical discharge capacity for drain materials through compare and analyze the time-settlement behavior with drain spacing and the compression index and consolidation coefficient obtained by laboratory experiments and field monitoring system. 1. The relation of measurement settlement($S_m$) versus design settlement($S_t$) and measurement consolidation ratio($U_m$) versus design consolidation ratio($U_t$) were shown $S_m=(1.0{\sim}1.1)S_t$, $U_m=(1.13{\sim}1.17)U_t$ at 1.0m drain spacing and $S_m=(0.7{\sim}0.8)S_t$, $U_m=(0.92{\sim}0.99)U_t$ at l.5m drain spacing, respectively. 2. The relation of field compressing index($C_{cfield}$) and virgin compression index($V_{cclab.}$) was shown $C_{cfield}=(1.0{\sim}1.2)V_{cclab.}$, But it was nearly same value when considered the error with determination method of virgin compression index and prediction method of total settlement. 3. Field consolidation coefficient was larger than laboratory consolidation coefficient, and the consolidation coefficient ratio($C_h/C_v$) were $C_h=(2.4{\sim}3.0)C_v$. $C_h=(3.5{\sim}4.3)C_v$ at 1.0m and 1.5m drain spacing and increased with increasing of drain spacing. 4. The evaluation of vertical discharge capacity with drain spacing from the results of the consolidation coefficient ratio showed largely superior in case the Mebra drain and Amer drain than other drain materials at 1.0m and 1.5m drain spacing, while the values showed nearly same value in case same drain spacing.

• Journal of Ocean Engineering and Technology
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• v.32 no.3
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• pp.166-176
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• 2018

This paper presents a numerical sensitivity analysis for the simulation of the motion performance of an offshore structure in waves using computational fluid dynamics (CFD). Starting with 2D wave simulations with varying numerical parameters such as grid spacing and CFL value, proper numerical conditions were found for accurate wave propagation that avoids numerical diffusion problems. These results were mapped on 2D error distributions of wave amplitude and wave length against the numbers of grids per wave length and per wave height under a given CFL condition. Finally, the 2D numerical sensitivity result was validated through CFD simulation of the motion of a FPSO in waves showing good accuracy in motion RAOs compared with existing potential flow solutions.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06b
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• pp.25-27
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• 2006

음성인식 결과는 띄어쓰기 오류가 포함되어 있으며 이는 인식 결과에 대한 이후의 정보처리를 어렵게 하는 요인이 된다. 본 논문은 음성 인식 결과의 띄어쓰기 오류를 수정하기 위하여 품사 정보를 이용한 어절 재결합 기법을 기본 알고리즘으로 사용하고 추가로 음절 바이그램 및 4-gram 정보를 이용하는 띄어쓰기 오류 교정 방법을 제안하였다. 또한, 음성인식기의 출력으로 품사 정보가 부착된 경우와 미부착된 경우에 대한 비교 실험을 하였다. 품사 미부착된 경우에는 사전을 이용하여 품사 정보를 복원하였으며 N-gram 통계 정보를 적용했을 때 기본적인 어절 재결합 알고리즘만을 사용 경우보다 띄어쓰기 정확도가 향상되는 것을 확인하였다.

• Solar Energy
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• v.9 no.1
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• pp.62-69
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• 1989

This analysis is to investigate the influence of inflow angle when cooling air flows into PC (Printed Circuit) board channels. Flow between PC board channels with heat generating blocks is assumed laminar, incompressible, two-dimensional. Geometric parameters (block spacing (S), block height (H), block width (W) and channel height (L)) are held fixed. Inflow angle variations are $-10^{\circ},\;0^{\circ},\;10^{\circ}$, where uniform heat flux per unit axial length Q (W/m) from heated block surfaces is generated. The governing equations for velocity and temperature are solved by SIMPLE (Semi-Implicit Method Pressure for Linked Equation) algorithm. Nusselt number on each block surfaces is analyzed after a numerical calculation result. The result shows that the assumption on parallel inflow (inflow angle to channel, $0^{\circ}$) to PC board channels can be used without large error even when inflow' angle is varied.

• 한국전산유체공학회:학술대회논문집
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• 1999.11a
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• pp.95-107
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• 1999

The spatial error due to the non-conservative interpolation become first-order when second-order conservative schemes are used, discontinuities are located away from the overlapped regions, and if the length of the overlapped region is not proportional to the grid spacing. Therefore, the solution accuracy is ensured if two domains overlap each other with a fixed grid point and the interpolation is occurred in smooth flow regions. To validate the spatial and temporal accuracy due to the non-conservative interpolation, inviscid and viscous problems are tested.