• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.1
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• pp.67-73
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• 2011

Using the known result of the expected busy period for a controllable M/G/1 queueing model operating under the triadic Max (N, T, D) policy, its upper and lower bounds are derived to approximate its corresponding actual value. Both bounds are represented in terms of the expected busy periods for the dyadic Min (N, T), Min (N, D) and Min (T, D) and simple N, T and D operating policies. All three input variables N, T and D are equally contributed to construct such bounds for better estimation.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.1
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• pp.31-39
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• 2004

In this paper, an experimental study on the hydroelastic behaviors of a VLFS with L=5,000m was made considering a breakwater. The principal dimensions of the VLFS model were 9m${\times}$1.8${\times}$0.0108m(L${\times}$B${\times}$D) and the length of breakwater was 12.6m (1.4L). The distance between the VLFS and the breakwater varied from B/2 to 28. The wide tank test results were compared with the numerical predictions and the comparison showed a little gap along its longitudinal axis, in spite of using the very small model size due to the scale 1/555.5

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.1
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• pp.46-54
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• 2021

This study compared and analyzed the effects of forest tending works on the vertical distribution of wildfire fuel loads on Pinus densiflora stands in Gyeongbuk province. The study sites were located in Youngju and Bonghwa in Pinus densiflora stands. A total of 10 sample trees were collected for the development of the crown fuel vertical distribution model. The 6th NFI (National Forest Inventory) selected a sample point that only extracted from managed and unmanaged stands of Pinus densiflora in the Gyeongbuk province. The fitness index (F.I.) of the two models developed was 0.984 to 0.989, with the estimated parameter showing statistical significance (P<0.05). A s a results, the vertical distribution of wildfire fuel loads range of unmanaged stands was from 1m to 11m with the largest distribution at point 5m at the tree height. On the other hand, the vertical distribution of wildfire fuel loads range of the managed stands was from 1m to 15m with the largest distribution at the point of 8m at the tree height. The canopy bulk density was 0.16kg/㎥ for the managed stands and 0.25kg/㎥ for the unmanaged stands, unmanaged stands were about 1.6 times more than managed stands. This result is expected to be available for simulation through the implementation of the 3D model as crown fuel was analyzed in three dimensions.

• Journal of Korean Society on Water Environment
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• v.24 no.1
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• pp.7-18
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• 2008

The objective of this study was to develop and apply a water quality simulation model for the evaluation of ungaged watershed. The Modified WASP5 consisted of three sub-models, LOAD-M, DYN-M, and EUT-M. LOAD-M, an empirical model, estimates runoff loadings using point and non-point source data of villages. Daecheong Dam watershed was selected for the research to calibrate, verify and application of Modified-WASP5. LOAD-M model was established using field data collected from all items of water quality and water quantity gaging stations of the watersheds, and was applied to the ungauged watersheds, taking the watershed properties under consideration. The result of water quality simulation using ModifiedWASP5 shows that the observed BOD data of Yongpo and Daechong Dam in 1999 were 0.8 mg/L and 1.0 mg/L, and simulated data were 0.9 mg/L and 0.9 mg/L, respectively. In case of 1999, average BOD concentrations were 0.8 mg/L and 1.0 mg/L. Simulated concentration showed 1.1 mg/L and 1.5 mg/L, respectively. Generally, the simulation results were in good agreement with the observed data. This study was focused on formulating an integrated model for evaluating ungauged watersheds. Even though simulation results varied slightly due to limited availability of data, the model developed in this study would be a useful tool for the assessment and management of ungauged watersheds.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.2
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• pp.143-149
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• 1996

Forecasts of the monthly catches of anchovy in Korea were carried out by the seasonal Autoregressive Integrated Moving Average (ARIMA) model and spectral analysis. The seasonal ARIMA model is as follows: $$(1-0.431B)(1-B^{12})Z_t=(1-0.882B^{12})e_t$$ where: $Z_t=value$ at month $t;\;B^{p}$ is a backward shift operator, that is, $B^pZ_t=Z_{t-p};$ and $e_t=error$ term at month t, which is to forecast 24 months ahead the anchovy catches in Korea. The prediction error by the Box-Cox transformation on monthly anchovy catches in Korea was less than that by the logarithmic transformation. The equation of the Box-Cox transformation was $Y'=(Y^{0.58}-1)/0.58$. Forecasts of the monthly anchovy catches for $1991\~1992$, which were compared with the actual catches, had an absolute percentage error (APE) range of $1.0\~63.2\%$. Total observed annual catches in 1991 and 1992 were 170,293 M/T and 168,234 M/T respectively, while the predicted catches were 148,201 M/T and 148,834 M/T $(API\;13.0\%\;and\;11.5\%,\;respectively)$. The spectrum analysis of the monthly catches of anchovy showed some dominant fluctuations in the periods of 2.2, 6.1, 10.2 12.0 and 14.7 months. The spectrum analysis was also useful for selecting the ARIMA model.

• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.388-395
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• 2019

The purpose of this study is to suggest structural model and analyze design factors for the development of small greenhouse standardization model. The average dimensions of small greenhouse desired by urban farmers were 3.3m in width, 1.9m in eaves height, 2.7m in ridge height, 5.7m in length. The cladding materials for small greenhouse were preferred to glass, PC board and plastic film, framework to aluminum alloy and steel, and heating method in electrical energy. In addition, it was analyzed that small greenhouses need to develop structural model by dividing them into entry-level type and high-level type. The roof type that was used for entry-level type was arch shape, framework was steel pipe, cladding material was plastic film. On the other hand, high-level type was used in even span or dutch light type, framework with square hollow steel, cladding materials with glass or PC board. In consideration of these findings and practicality, this study developed four types of small greenhouses. The width, eaves height, ridges height, and length of the small greenhouses of even span type, which were covered with 5mm thick glass and 6mm thick PC board were 3m, 2.2m, 2.9m, and 6m, respectively. The small greenhouse of dutch light type covered with 5mm thick glass was designed with 3.8m in with, 2.2m in eaves height, 2.9m in ridges height, and 6m in length. The width, eaves height, ridges height, and length of the arch shape small greenhouse covered with a 0.15mm PO film were 3m, 1.5m, 2.8m, and 6m, respectively.

• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.1043-1059
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• 2021

Forest and agricultural land are very important factors in the environmental ecosystem and securing food resources. Forest and agricultural land should be monitored regularly. CAS500-4 data are expected to be effectively used as a supplement of monitoring forest and agricultural land. Prior to the launch of the CAS500-4, the relative canopy height error analysis of the digital elevation model on South Korea was performed to determine the vertical target accuracy. Especially, by considering area of interest of the CAS500-4 (mountainous or agricultural area), it is conducted that vertical error analysis according to the slope and canopy. For Gongju, Jeju, and Samcheok, the average root mean squared differences were calculated compared to the drone LiDAR digitalsurface models, which were filmed in autumn and winter and the 5 m digital elevation model from the National Geographic Information Institute. As a result, the Shuttle radar topography mission digital elevation model showed a root mean squared differences of about 8.35, 8.19, and 7.49 m, respectively, while the Copernicus digital elevation model showed a root mean squared differences of about 5.65, 6.73, and 7.39 m, respectively. In addition, the root mean squared difference of shuttle radar topography mission digital elevation model and the Copernicus digital elevation model according to the slope angle were estimated on South Korea compared to the 5 m digital elevation model from the National Geographic Information Institute. At the slope angle of between 0° to 5°, root mean squared differences of the Shuttle radar topography mission digital elevation model and the Copernicus digital elevation model showed 3.62 and 2.52 m, respectively. On the other hands root mean squared differences of the Shuttle radar topography mission digital elevation model and the Copernicus digital elevation model respectively showed about 10.16 and 11.62 m at the slope angle of 35° or higher.

• Corrosion Science and Technology
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• v.9 no.1
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• pp.29-33
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• 2010

Laser machining technique, which is used focusing pulse YAG laser beam irradiation was applied to form area ratio controlled model cut-edge on pre painted Zn coated steels. A corrosion behavior of formed model cut-edge was investigated by rest potential measurement in 1 mol $m^{-3}$ NaCl with and without 0.5 kmol $m^{-3}$ $H_3BO_4$/0.05kmol$m^{-3}$ $Na_2B_4O_7$. The rest potential showed almost constant value with fluctuations. The amplitude of fluctuations increased with exposed area of steel surface. White corrosion products of zinc oxide and simonkollite was formed after the experiments at the formed model cut-edge.

• The Journal of Korean Medicine
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• v.25 no.2
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• pp.127-137
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• 2004

Objectives : The purpose of this investigation was to evaluate the effects of Sohaphyang-won (SH) on the alteration in gene expression in a hypoxia model using cultured rat cortical cells. Methods : E18 rat cortical cells were grown in neurobasal medium containing B27 supplement. On 12 DIV, SH was added ($20\mu\textrm{g}/ml$) to the culture media for 24 hrs. On 14 DIV, cells were given a hypoxic insult (2% O2/5% CO2, $37^{\circ}C$, 3 hrs), returned to normoxia and cultured for another 24 hrs. Total RNA was prepared from SH-untreated (control) and -treated cultures and alteration in gene expression was analyzed by microarray using rat 5K-TwinChips. Results : Effects on some of the genes whose functions are implicated in neural viability are as follows: 1) For most of the genes altered in expression, the global M values were between -05 to +0.5, Among these, 1517 genes were increased in their expression by more than global M +0.1, while 1480 genes were decreased by more than global M -0.1. 2) The expression of apoptosis-related genes such as Bad (global M =0.35), tumor protein p53 (T53) (global M =0.28) were increased, while v-akt murine thymoma viral oncogene homolog 1 (Akt1) was decreased. 3) The expression of hemoglobin alpha 1 (probably neuroglobin) was increased by about 3.2-fold (global M =1.7). 4) The expression of antioxidation-related catalase gene was increased (global M =0.26). 5) The expression of PKCzeta (prkcz), an upstream kinase of MAPK, was increased (global M =0.29). 6) The expression of retinoic acid receptor alpha (RAR), which may regulate transcription in hypoxic stress, was increased (global M =10.27). Conclusions : In summary, the microarray data suggest that SH doesn't increase the expression of oxygen capture-, anti-oxidation- and 'response to stress' -related genes but decreases some anti-apoptosis genes which would help protect the hypoxic cells from apoptosis.

• Korean Journal of Radiology
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• v.22 no.1
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• pp.118-130
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• 2021

Objective: This study aimed to investigate the blood-brain barrier (BBB) disruption in mild traumatic brain injury (mTBI) patients with post-concussion syndrome (PCS) using dynamic contrast-enhanced (DCE) magnetic resonance (MR) imaging and automatic whole brain segmentation. Materials and Methods: Forty-two consecutive mTBI patients with PCS who had undergone post-traumatic MR imaging, including DCE MR imaging, between October 2016 and April 2018, and 29 controls with DCE MR imaging were included in this retrospective study. After performing three-dimensional T1-based brain segmentation with FreeSurfer software (Laboratory for Computational Neuroimaging), the mean K^trans and v_p from DCE MR imaging (derived using the Patlak model and extended Tofts and Kermode model) were analyzed in the bilateral cerebral/cerebellar cortex, bilateral cerebral/cerebellar white matter (WM), and brainstem. K^trans values of the mTBI patients and controls were calculated using both models to identify the model that better reflected the increased permeability owing to mTBI (tendency toward higher K^trans values in mTBI patients than in controls). The Mann-Whitney U test and Spearman rank correlation test were performed to compare the mean K^trans and v_p between the two groups and correlate K^trans and v_p with neuropsychological tests for mTBI patients. Results: Increased permeability owing to mTBI was observed in the Patlak model but not in the extended Tofts and Kermode model. In the Patlak model, the mean K^trans in the bilateral cerebral cortex was significantly higher in mTBI patients than in controls (p = 0.042). The mean v_p values in the bilateral cerebellar WM and brainstem were significantly lower in mTBI patients than in controls (p = 0.009 and p = 0.011, respectively). The mean K^trans of the bilateral cerebral cortex was significantly higher in patients with atypical performance in the auditory continuous performance test (commission errors) than in average or good performers (p = 0.041). Conclusion: BBB disruption, as reflected by the increased K^trans and decreased v_p values from the Patlak model, was observed throughout the bilateral cerebral cortex, bilateral cerebellar WM, and brainstem in mTBI patients with PCS.