• Korean Chemical Engineering Research
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• v.62 no.3
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• pp.214-224
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• 2024

Valves play an essential role in a chemical plant such as regulating fluid flow and pressure. Therefore, optimal selection of the valve size and type is essential task. Valve size and type have been selected based on theoretical formulas about calculating valve sizing coefficient (Cv). However, this approach has limitations such as requiring expert knowledge and consuming substantial time and costs. Herein, this study developed a model for predicting valve sizes and types using machine learning. We developed models using four algorithms: ANN, Random Forest, XGBoost, and Catboost and model performances were evaluated using NRMSE & R² score for size prediction and F1 score for type prediction. Additionally, a case study was conducted to explore the impact of phases on valve selection, using four datasets: total fluids, liquids, gases, and steam. As a result of the study, for valve size prediction, total fluid, liquid, and gas dataset demonstrated the best performance with Catboost (Based on R², total: 0.99216, liquid: 0.98602, gas: 0.99300. Based on NRMSE, total: 0.04072, liquid: 0.04886, gas: 0.03619) and steam dataset showed the best performance with RandomForest (R²: 0.99028, NRMSE: 0.03493). For valve type prediction, Catboost outperformed all datasets with the highest F1 scores (total: 0.95766, liquids: 0.96264, gases: 0.95770, steam: 1.0000). In Engineering Procurement Construction industry, the proposed fluid-specific machine learning-based model is expected to guide the selection of suitable valves based on given process conditions and facilitate faster decision-making.

• Investigative Magnetic Resonance Imaging
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• v.18 no.1
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• pp.17-24
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• 2014

Purpose : To determine whether high-resolution contrast-enhanced three dimensional imaging with spoiled gradient-recalled sequence (HR-CE 3D-SPGR) plays a meaningful role in the assessment of intracranial vertebral artery (ICVA) and posterior inferior cerebellar artery (PICA) in lateral medullary infarction (LMI). Materials and Methods: Twenty-five patients confirmed with LMI were retrospectively enrolled with approval by the IRB of our institute, and 3T MRI with HR-CE 3D-SPGR and contrast-enhanced magnetic resonance angiography (CE-MRA) were performed. Two radiologists who were blinded to clinical information and other brain MR images including diffusion weighted image independently evaluated arterial lesions in ICVA and PICA. The demographic characteristics, the area of LMI and cerebellar involvement were analyzed and compared between patients with arterial lesion in ICVA only and patients with arterial lesions in both ICVA and PICA on HR-CE 3D-SPGR. Results: Twenty-two of twenty-five LMI patients had arterial lesions in ICVA or PICA on HR-CE 3D SPGR. However twelve arterial lesions in PICA were not shown on CE-MRA. Concurrent cerebellar involvement appeared more in LMI patients with arterial lesion in ICVA and PICA than those with arterial lesion in ICVA alone (p = 0.069). Conclusion: HR-CE 3D-SPGR can help evaluate arterial lesions in ICVA and PICA for LMI patients.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.425-437
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• 2007

Flow distribution of water and sedimentation rate were investigated to understand the hydrodynamics and settling characteristics of particulate materials in a constructed wetland for treatment of non-point sources pollutants, the Sihwa constructed wetland, Korea. The Sihwa constructed wetland is divided into three sub-wetlands(the Banwol, the Donghwa and the Samhwa wetlands) to treat the polluted water from three streams, the Banwol stream, the Donghwa stream and the Samhwa stream. From the results of water flow experiment using dye(Rhodamine 50WT Red), it was found that the water flow in the wetland was prevailing at the waterway and open water. Dye was spread slowly in the closed water area planted by plants. The mean hydraulic retention time(HRT) at the upper area of high wetland and lower wetland of Banwol, was found to be 34.1 hr at the upper area and 74.6 hr at the lower area respectively, totaling approximately 108.7 hr(4.5 days). The sedimentation rate was higher at lower area(sites of B, C and D) of the wetland than upper area(site of A which is settling zone). Based on the forecast for 20 years as to the amount of sediment that can be deposited in the open water in the future, the sediment depth of each area would be like this: A: 6.3 cm, B: 8.3 cm, C: 7.0 cm, D: 9.5 cm. The contents of organic materials in the sediment deposited within the sediment trap were found to be higher overly in the first investigation period which had much rainfall, and B, C and D areas were found to have an increased COD accumulation than A area. Also, nitrogen and phosphorus were found to increase in the down-stream of the wetland. The results of this study suggest that a sustainable research and management for the characteristics of water flow pattern and sedimentation changeable as time passes is needs to maintain or improve the efficiency of water treatment in the constructed wetland.

• The Korean Journal of Nuclear Medicine
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• v.28 no.3
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• pp.384-390
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• 1994

Authors retrospectively compared the 99mTc MDP bone scans and corresponding MR imagings in 20 patients with histologically proven malignancy, Mean interval of the two studies was 16.6 days, Cancer diagnosis Included 8 lung, 2 each of colon, breast, stomach, 1 each of prostate, thyroid, malignant lymphoma and 3 adenocarcinoma of unknown primary site. Of the 105 regions compared, :t6 regions were positive for metastases in bone scans or MR imagings. 30 regions(65.2%) were positive by bone scan and 44 regions(95.7%) by MR imaging. 87 regions(82.9%) were concordantly positive or negative by bone scan and MR imaging, but 18 regions(17.1%) were discordant. In the discordant regions, 16 regions positive in MR imaging were negative in bone scan. The greatest number of discordant findings occured in the cervical region and in the patient with stomach cancer. Our results suggest that the sensitivity of MR Imaging is greater than that of bone scan in detecting spinal metastases. And bone scan is useful screening test of metastasis for evaluating entire skeleton including spine.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.3 s.47
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• pp.393-397
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• 2004

L-Carnitine $({\beta}-hydroxy-{\gamma}-trimethyl-ammoniumbutyric{\;}acid)$ is a small water-soluble molecule important in mammalian fat metabolism. It is essential for the normal oxidation of fatty acids by the mitochondria, and is involved in the trans-esterification and excretion of acyl-CoA esters. In this paper, to investigate the relationship between aging and L-carnitine, we investigated the effects of in vitro matrix-metalloproteinase (MMP) inhibition and activity and expression of UYA-induced MMPs in human skin fibroblasts. Also, we studied to develop as anti-aging cosmetics with L-carnitine. Fluorometric assays of the proteolytic activities of MMP-1 (collagenase) were performed using fluorescent collagen substrates. ELISA (enzyme linked immune sorbent assay), gelatin-substrate zymography, RT-PCR ELISA techniques were used for the effects of L-carnitine on MMP expression, activity, and MMP mRNA expression in UVA irradiated fibroblast $(5\;J/cm^2)$, respectively. In addition, we performed clinical study with L-carnitine cream. L-carnitine inhibited the activities of MMP-1 in a dose-dependent manner and the $IC_{50}$ values calculated from semi-log plots were 2.45 mM, and L-carnitine showed strong inhibition on MMP-2 (gelatinase) activity in UVA irradiated fibroblast by zymography. Also, UVA induced MMP-1, 2 expression was reduced $43\%,\;53\%$ by treated with L-carnitine at 1.25 mM, and MMP-1 mRNA expression was reduced dose-dependent manner. Therefore L-carnitine was able to significantly inhibit the MMP activity, and regulate MMP expression in protein and mRNA level. The results of clinical study showed that $1.0\%$ L-carnitine treated group reduced wrinkle significantly compared with placebo treated group (P<0.05). All these results suggest that L-carnitine may be useful as new anti-aging cosmetics for protection against UVA induced Mm expression and activity.

• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.279-285
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• 2019

To estimate daily canopy photosynthesis, accurate estimation of canopy light interception according to a daily solar position is needed. However, this process needs a lot of cost, time, manpower, and difficulty when measuring manually. Various modeling approaches have been applied so far, but it was difficult to accurately estimate light interception by conventional methods. The objective of this study is to estimate the spatial distributions of light interception and photosynthetic rate of paprika with time by using 3D-scanned plant models and optical simulation. Structural models of greenhouse paprika were constructed with a portable 3D scanner. To investigate the change in canopy light interception by surrounding plants, the 3D paprika models were arranged at $1{\times}1$ and $9{\times}9$ isotropic forms with a distance of 60 cm between plants. The light interception was obtained by optical simulation, and the photosynthetic rate was calculated by a rectangular hyperbola model. The spatial distributions of canopy light interception of the 3D paprika model showed different patterns with solar altitude at 9:00, 12:00, and 15:00. The total canopy light interception decreased with an increase of surrounding plants like an arrangement of $9{\times}9$, and the decreasing rate was lowest at 12:00. The canopy photosynthetic rate showed a similar tendency with the canopy light interception, but its decreasing rate was lower than that of the light interception due to the saturation of photosynthetic rate of upper leaves of the plants. In this study, by using the 3D-scanned plant model and optical simulation, it was possible to analyze the light interception and photosynthesis of plant canopy under various conditions, and it can be an effective way to estimate accurate light interception and photosynthesis of plants.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.3
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• pp.203-208
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• 2007

To develop a new whitening agent for cosmetics from natural products, Pimpinella brachcarpa was selected for its inhibitory effect on melanogenesis in B16 melanoma cells. Crude ethanolic extract of P. brachycarpa and its four fractions-hexane, ethyl acetate(EtOAc), butanol and aqueous were evaluated for antioxidative effects and tyrosinase inhibitory activity. To elucidate the mechanism of active compounds of P. brachycarpa, we investigated the changes in protein level of tyrosinase, TRP-1 and TRP-2 using Western blotting and the changes in mRNA level of tyrosinase using RT-PCR technique. Following UV irradiation, expression of ET-1 in HaCaT keratinocytes was measured by quantitative enzyme immunoassay(EIA) using human ET-1 antibody. Crude ethanolic extract of P. brachycarpa and its four fractions-hexane, EtOAc, butanol and aqueous had free radical scavenging effect by 87.2, 2.5, 97.2, 80.5, 49.8% at 100 ${\mu}g/mL$ and tyrosinase inhibitory effect by 18.3, 15.1, 55.4, 13.1, 0 % at 100 ${\mu}g/mL$. P. brachycarpa EtOAc fraction significantly inhibited melanin production in B16 melanoma cells. Treatment with P. brachycarpa extract for 72 h suppressed the biosynthesis of melanin up to 58 % at 100 ${\mu}g/mL$. Especially, the EtOAc fraction of P. brachycarpa reduced the tyrosinase activity and tyrosinase expression in B16 melanoma cells in a dose-dependent manner. mRNA levels of tyrosinase and TRP-1 were markedly reduced by the EtOAc fraction of P. brachycarpa. Moreover, at the concentrations of $12.5{\sim}50{\mu}g/mL$ of the fraction, the production of UV-induced ET-1 in HaCaT keratinocytes(24 h after 8 $mJ/cm^2$ UVB irradiation) was reduced about 40%(p<0.05). P. brachycarpa could be used as a new natural skin-whitening agent due to the inhibitory effect of on melanin biosynthesis and endothelin-1 expression.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.3
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• pp.75-85
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• 2009

This work proposes a 13b 100MS/s 0.13um CMOS ADC for 3G communication systems such as two-carrier W-CDMA applications simultaneously requiring high resolution, low power, and small size at high speed. The proposed ADC employs a four-step pipeline architecture to optimize power consumption and chip area at the target resolution and sampling rate. Area-efficient high-speed high-resolution gate-bootstrapping circuits are implemented at the sampling switches of the input SHA to maintain signal linearity over the Nyquist rate even at a 1.0V supply operation. The cascode compensation technique on a low-impedance path implemented in the two-stage amplifiers of the SHA and MDAC simultaneously achieves the required operation speed and phase margin with more reduced power consumption than the Miller compensation technique. Low-glitch dynamic latches in sub-ranging flash ADCs reduce kickback-noise referred to the differential input stage of the comparator by isolating the input stage from output nodes to improve system accuracy. The proposed low-noise current and voltage references based on triple negative T.C. circuits are employed on chip with optional off-chip reference voltages. The prototype ADC in a 0.13um 1P8M CMOS technology demonstrates the measured DNL and INL within 0.70LSB and 1.79LSB, respectively. The ADC shows a maximum SNDR of 64.5dB and a maximum SFDR of 78.0dB at 100MS/s, respectively. The ABC with an active die area of $1.22mm^2$ consumes 42.0mW at 100MS/s and a 1.2V supply, corresponding to a FOM of 0.31pJ/conv-step.

• Economic and Environmental Geology
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• v.36 no.6
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• pp.441-455
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• 2003

The most common water types are found to be Ca-$HCO_3$, Ca-Na-$HCO_3$ and Ca-Na-$HCO_3$-Cl in Gwangju groundwater. Groundwater near the Gwangju stream are characterized Ca-Cl water type, with over 50 mg/L of C1- and 400 ${\mu}$S/cm of EC. The systematic variation of $Cl^-$, $HCO_3^-$,- EC and ${\gamma}^{18}O$ values in groundwater with distance away from drainages is caused by streamwater infiltration. Stable isotope data indicate that ${\gamma}$D and ${\gamma}^{18}O$ values of groundwaters near drainages were enriched by evaporation effect, showing a equation of ${\gamma}$D=7. 1${\times}{\gamma}^{18}O$-1. ${\gamma}^{18}O$ values over -6${\textperthansand}$ are anomalous in the unconfined groundwater zones, which are influenced by the local surface water enriched in $^{18}O$ composition. Groundwater in highland shows remarkably light ${\gamma}^{18}O$ values below -8$\textperthousand$. The infiltration of streamwater is dominant in unconfined alluvium aquifer near drainages. ${\gamma}^{13}$CDIC values (-17.6∼-15.2$\textperthousand$) of groundwaters near drainages revealed that dissolved inorganic carbon (DIC) is predominantly originated from natural soil-derived $CO_2$. ${\gamma}^{15}N$ and ${\gamma}^{18}O$ values of nitrate are 0∼17.0${\textperthansand}$ and 6.6∼17.4${\textperthansand}$, respectively. Relationship between ${\gamma}^{15}N$ and ${\gamma}^{18}O$ shows a systematic isotopic fractionation caused by denitrification of 40∼60%, suggesting that the major source of groundwater nitrate originated from nitrate of soils, and mixing nitrate of soil and sewage or manure.

• Microbiology and Biotechnology Letters
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• v.38 no.4
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• pp.414-419
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• 2010

Plants extracts are good resources to find functional compounds for human health. The following eight plants were collected and total phenolic contents were determined. Acer psedo-siebolianum showed the highest phenolic contents, 16.4 mg/g, whereas Cercidiphyllum japonica showed the lowest contents, 1.9 mg/g. The DPPH free radical scavenging capacities of the plant extracts showed high activity in following order : Acer ginnala ($21.3\;{\mu}g/mL$) > Cornus walteri ($23.9\;{\mu}g/mL$) > Distylum racemosum ($29.2\;{\mu}g/mL$) > Castanopsis cuspidata var. Thunbergii ($31.7\;{\mu}g/mL$) > Acer psedo-siebolianum ($34.6\;{\mu}g/mL$) > Thuijopsis dolabrata cv. Aurea ($53.1\;{\mu}g/mL$) > Cercidiphyllum Japonica ($115.2\;{\mu}g/mL$). Also the mushroom tyrosinase inhibitory activities of total extracts were determined at different concentration. D. racemosum extract showed highest (49.1% at 1,000 mg) in inhibitory activity than other seven extracts. The ethanol fraction $IC_{50}$ value: $118.1\;{\mu}g/mL$) from D. racemosum showed more inhibitory activity than ethyl acetate fraction ($IC_{50}$ value: $203\;{\mu}g/mL$). The ethanol fraction on showed no significant cytotoxicity in B16/F1 cells line up to $60\;{\mu}g/mL$. Over $80\;{\mu}g/mL$ of ethanol fraction showed cytotoxicity in B16/F1 cells. The melanin contents of cells were significantly attenuated by ethanol fraction in a dose-dependent manner. The $IC_{50}$ value of ethanol fraction was $75.4\;{\mu}g/mL$.