• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.2
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• pp.217-230
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• 2022

The adequate control of TBM face pressure is of vital importance to maintain face stability by preventing face collapse and surface settlement. An EPB shield TBM excavates the ground by applying face pressure with the excavated soil in the pressure chamber. One of the challenges during the EPB shield TBM operation is the control of face pressure due to difficulty in managing the excavated soil. In this study, the face pressure of an EPB shield TBM was predicted using the geological and operational data acquired from a domestic TBM tunnel site. Four machine learning algorithms: KNN (K-Nearest Neighbors), SVM (Support Vector Machine), RF (Random Forest), and XGB (eXtreme Gradient Boosting) were applied to predict the face pressure. The model comparison results showed that the RF model yielded the lowest RMSE (Root Mean Square Error) value of 7.35 kPa. Therefore, the RF model was selected as the optimal machine learning algorithm. In addition, the feature importance of the RF model was analyzed to evaluate appropriately the influence of each feature on the face pressure. The water pressure indicated the highest influence, and the importance of the geological conditions was higher in general than that of the operation features in the considered site.

• Journal of Korea Water Resources Association
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• v.55 no.9
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• pp.687-700
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• 2022

For comprehensively assessment the water resources performance of multi-purpose dams and water supply dams in South Korea, a methodology was proposed to utilize the durational reliability along with the integrated auxiliary indicators including resiliency, dimensionless vulnerability, water resource efficiency, specific inflow, and specific water supply. In addition, for the purpose of sustainable dam operation in the future, a plan to grade the water resources performance was presented to periodically evaluate the performance and determine the priority of each dam's structural or non-structural planning according to the evaluation results. As major results, in the case of Sumjingang Dam, the durational reliability was 99.0%, but the integrated auxiliary index was the lowest of 44 points, which was 5th grade. This means that despite the current high reliability, hydrological changes due to future climate change or regional change of water demand-supply balance can have significant impacts on the water resources performances. In contrast, the Chungju Dam with a durational reliability of 93.0%, which is below the average among all multi-purpose dams, shows the 76 points of the integrated auxiliary index, which is 3^rd highest following the Soyanggang Dam and the Namgang Dam. Nevertheless, due to the size of the basin, the specific inflow is sufficiently high as 185%, so the actual performance could be evaluated relatively high. The water supply dams designed for a single purpose tend to be evaluated relatively high because they have a high proportion of industrial and municipal water supply and have enough room for the supply capacity.

• Journal of Korea Water Resources Association
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• v.56 no.9
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• pp.575-586
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• 2023

River vegetation has important functions such as providing a habitat for the river ecosystem and physical stability of the river bank. It also has adverse effects such as aggravating flood damages due to the increase in roughness coefficient and drag forces. River vegetation management is very important in finding a balance between flood and ecological management. There are still many uncertainties about the effect of vegetation on rivers. In this study, in order to analyze the effect of vegetated flow, the flow patterns according to the vegetation roughness are analyzed through a two-dimensional unsteady flow model for Chopyeong island of the Imjin River. According to the results of the 2D flow analysis using the HEC-RAS 2D model, the velocity distribution in the bend of the Imjin River was greatly affected by the vegetation roughness of Chopyeong Island. The formation of the main flow outside the bend of Chopyeong Island during flooding is presumed due to the influence of tree and grass on Chopyeong Island. If tree are distributed throughout Chopyeong Island, the velocity outside the bend is expected to be higher. River vegetation causes the effect of raising the water level, and could cause a change in the velocity distribution.

• Analytical Science and Technology
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• v.19 no.5
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• pp.369-375
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• 2006

Calibration gas mixtures were prepared using dynamic volumetric method according to ISO 6145-5 and the uncertainty was evaluated. Ten identical capillaries with 0.25 mm in inner diameter and 50 cm in length were applied in this system. Dilution ratio of parent gas was determined by the number of capillaries that passes parent gas and that passes balance gas through. Capillaries were made of Teflon which had good chemical stability against adsorption of gaseous substances. Mechanical valves were introduced in this system in order to minimize the thermal effect of solenoid valves. Concentration of prepared gases were compared with master grade standard gases in cylinders made by RiGAS Co. and calibration of the instrument were completed using comparison method according to ISO 6143. Experimental results showed that the coefficient of variance of diluted oxygen standard gases showed less then 0.2% in most dilution range, that of diluted hydrogen sulfide standard gases showed less then 1.0%. Therefore, it is proven that the standard gases prepared by this system are appropriate to be used as a calibration standards in ambient monitoring, etc.

• 한국유가공학회:학술대회논문집
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• 2002.04a
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• pp.59-60
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• 2002

Edible films such as wax coatings, sugar and chocolate covers, and sausage casings, have been used in food applications for years$^{(1)}$ However, interest in edible films and biodegradable polymers has been renewed due to concerns about the environment, a need to reduce the quantity of disposable packaging, and demand by the consumer for higher quality food products. Edible films can function as secondary packaging materials to enhance food quality and reduce the amount of traditional packaging needed. For example, edible films can serve to enhance food quality by acting as moisture and gas barriers, thus, providing protection to a food product after the primary packaging is opened. Edible films are not meant to replace synthetic packaging materials; instead, they provide the potential as food packagings where traditional synthetic or biodegradable plastics cannot function. For instance, edible films can be used as convenient soluble pouches containing single-servings for products such as instant noodles and soup/seasoning combination. In the food industry, they can be used as ingredient delivery systems for delivering pre-measured ingredients during processing. Edible films also can provide the food processors with a variety of new opportunities for product development and processing. Depends on materials of edible films, they also can be sources of nutritional supplements. Especially, whey proteins have excellent amino acid balance while some edible films resources lack adequate amount of certain amino acids, for example, soy protein is low in methionine and wheat flour is low in lysine$^{(2)}$. Whey proteins have a surplus of the essential amino acid lysine, threonine, methionine and isoleucine. Thus, the idea of using whey protein-based films to individually pack cereal products, which often deficient in these amino acids, become very attractive$^{(3)}$. Whey is a by-product of cheese manufacturing and much of annual production is not utilized$^{(4)}$. Development of edible films from whey protein is one of the ways to recover whey from dairy industry waste. Whey proteins as raw materials of film production can be obtained at inexpensive cost. I hypothesize that it is possible to make whey protein-based edible films with improved moisture barrier properties without significantly altering other properties by producing whey protein/lipid emulsion films and these films will be suitable far food applications. The fellowing are the specific otjectives of this research: 1. Develop whey protein/lipid emulsion edible films and determine their microstructures, barrier (moisture and oxygen) and mechanical (tensile strength and elongation) properties. 2. Study the nature of interactions involved in the formation and stability of the films. 3. Investigate thermal properties, heat sealability, and sealing properties of the films. 4. Demonstrate suitability of their application in foods as packaging materials. Methodologies were developed to produce edible films from whey protein isolate (WPI) and concentrate (WPC), and film-forming procedure was optimized. Lipids, butter fat (BF) and candelilla wax (CW), were added into film-forming solutions to produce whey protein/lipid emulsion edible films. Significant reduction in water vapor and oxygen permeabilities of the films could be achieved upon addition of BF and CW. Mechanical properties were also influenced by the lipid type. Microstructures of the films accounted for the differences in their barrier and mechanical properties. Studies with bond-dissociating agents indicated that disulfide and hydrogen bonds, cooperatively, were the primary forces involved in the formation and stability of whey protein/lipid emulsion films. Contribution of hydrophobic interactions was secondary. Thermal properties of the films were studied using differential scanning calorimetry, and the results were used to optimize heat-sealing conditions for the films. Electron spectroscopy for chemical analysis (ESCA) was used to study the nature of the interfacial interaction of sealed films. All films were heat sealable and showed good seal strengths while the plasticizer type influenced optimum heat-sealing temperatures of the films, 130$^{\circ}$C for sorbitol-plasticized WPI films and 110$^{\circ}$C for glycerol-plasticized WPI films. ESCA spectra showed that the main interactions responsible for the heat-sealed joint of whey protein-based edible films were hydrogen bonds and covalent bonds involving C-0-H and N-C components. Finally, solubility in water, moisture contents, moisture sorption isotherms and sensory attributes (using a trained sensory panel) of the films were determined. Solubility was influenced primarily by the plasticizer in the films, and the higher the plasticizer content, the greater was the solubility of the films in water. Moisture contents of the films showed a strong relationship with moisture sorption isotherm properties of the films. Lower moisture content of the films resulted in lower equilibrium moisture contents at all aw levels. Sensory evaluation of the films revealed that no distinctive odor existed in WPI films. All films tested showed slight sweetness and adhesiveness. Films with lipids were scored as being opaque while films without lipids were scored to be clear. Whey protein/lipid emulsion edible films may be suitable for packaging of powder mix and should be suitable for packaging of non-hygroscopic foods$^{(5,6,7,8,)}$.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1520-1521
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• 2008

There are several ways to demonstrate white organic light emitting diodes (OLEDs) for displays and solid state lighting applications. Among these approaches are the stacked three primary or two complementary colors light-emitting layers, multiple-doped emissive layer, and excimer and exciplex emission [1-10]. We report on white phosphorescent excimer devices by using two light emitting materials based on platinum complexes. These devices showed a peak EQE of 15.7%, with an EQE of 14.5% (17 lm/W) at $500\;cd/m^2$, and a noticeable improvement in both the CIE coordinates (0.381, 0.401) and CRI (81). Devices with the structure ITO/PEDOT:PSS/TCTA (30 nm)/26 mCPy: 12% FPt (10 nm) /26 mCPy: 2% Pt-4 (15 nm)/BCP (40 nm)/CsF/Al [device 1], ITO/PEDOT:PSS/TCTA (30 nm)/26 mCPy: 2% Pt-4 (15 nm)/26 mCPy: 12% FPt (10 nm)/BCP (40 nm)/CsF/Al [device 2], and ITO/PEDOT:PSS/TCTA (30 nm)/26 mCPy: 2% Pt-4: 12% FPt (25 nm)/BCP (40 nm)/CsF/Al [device 3] were fabricated. In these cases, the emissive layer was either the double-layer of 26 mCPy:12% FPt and 15 nm 26 mCPy: 2% Pt-4, or the single layer of 26mCPy with simultaneous doping of Pt-4 and FPt. Device characterization indicates that the CIE coordinates/CRI of device 2 were (0.341, 0.394)/75, (0.295, 0.365)/70 at 5 V and 7 V, respectively. Significant change in EL spectra with the drive voltage was observed for device 2 indicating a shift in the carrier recombination zone, while relatively stable EL spectra was observed for device 1. This indicates a better charge trapping in Pt-4 doped layers [10]. On the other hand, device 3 having a single light-emitting layer (doped simultaneously) emitted a board spectrum combining emission from the Pt-4 monomer and FPt excimer. Moreover, excellent color stability independent of the drive voltage was observed in this case. The CIE coordinates/CRI at 4 V ($40\;cd/m^2$) and 7 V ($7100\;cd/m^2$) were (0.441, 0.421)/83 and (0.440, 0.427)/81, respectively. A balance in the EL spectra can be further obtained by lowering the doping ratio of FPt. In this regard, devices with FPt concentration of 8% (denoted as device 4) were fabricated and characterized. A shift in the CIE coordinates of device 4 from (0.441, 0.421) to (0.382, 0.401) was observed due to an increase in the emission intensity ratio of Pt-4 monomer to FPt excimer. It is worth noting that the CRI values remained above 80 for such device structure. Moreover, a noticeable stability in the EL spectra with respect to changing bias voltage was measured indicating a uniform region for exciton formation. A summary of device characteristics for all cases discussed above is shown in table 1. The forward light output in each case is approximately $500\;cd/m^2$. Other parameters listed are driving voltage (Bias), current density (J), external quantum efficiency (EQE), power efficiency (P.E.), luminous efficiency (cd/A), and CIE coordinates. To conclude, a highly efficient white phosphorescent excimer-based OLEDs made with two light-emitting platinum complexes and having a simple structure showed improved EL characteristics and color properties. The EQE of these devices at $500\;cd/m^2$ is 14.5% with a corresponding power efficiency of 17 lm/W, CIE coordinates of (0.382, 0.401), and CRI of 81.

• Journal of Legislation Research
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• no.44
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• pp.241-281
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• 2013

First and foremost, a discussion concerning government structure has to be done in connection with the state form and the governmental form. For practical reasons, there is a need to balance the principle of legality and its exceptions under the Government Organization Act. To ensure the flexibility of government structure with respect to the principle of legality, the National Assembly should accept the government structure requested by the newly elected government. This mitigates the rigidity of the principle of the legality within the government organizations. However, excessive changes by each government could violate the principle of legality asked by Constitution. In this sense, arbitrary modification with respect to the government structure by the newly elected government is not desirable. The long term stability of the government organization is required in any case. Secondly, general administrative agencies, other than Executive Ministries, should not be established under the direct order of the President without the control of the Prime Minister. A hierarchy of the executive branch (President->Prime Minister-> Executive Ministries) is stipulated in the Constitution. Establishing a hierarchy of President -> executive institution should be considered unconstitutional. Therefore, only the Presidential Secretariat and institutions with special functions can be established in the Presidential Office. Establishing general administrative agencies in the Presidential Office for convenience purposes is against the spirit of the current Constitution. Consequently, only the office of staffs and special agencies can be placed in the presidential office. It is against the spirit of the current Constitution to found administrative agencies under the presidential office for convenience. Thirdly, the office of the Prime Minister should be the backbone of internal affairs. In that sense, the President, as the head of state, should focus on the big picture such as the direction of the State, while the Cabinet headed by the Prime Minister should be responsible for the daily affairs of the State. The cabinet surrounding the Prime Minister must control all the ordinary affairs of the State, while the President, as the head of the State, should focus on the big picture of blueprinting the aim of the State. Lastly, the Office of the Prime Minister and Executive Ministries are the two main bodies of the executive branch. It is important to reduce the confusion caused by repeated changes in the names of Executive Ministries, to restore the traditional names and authorities of these institutions, and to rehabilitate the legitimacy of the State. For the Korean democracy to take its roots, a systematic way of stabilizing a law-governed democratic country is needed. There is also the need not only to reform security and economic agencies, but also to rationally solve the integration of technique and policy, according to the changes of time.

• Journal of the Korean Society of Groundwater Environment
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• v.4 no.1
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• pp.41-53
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• 1997

Geochemical data of soil and water samples were presented in order to assess the environmental impart for drinking water sites. Microscopic observation of rock samples and physical and chemical analysis of soil and water samples were undertaken. The geology of study areas are classified into three groups such as granitic rocks, meta-sedimentary rocks and sedimentary rocks. Enrichment of heavy metals derived from those rocks is not found in this study areas. Soils were analyzed for Cu, Pb, Zn, Cd and Cr using AAS extracted by HNO$_3$+HClO$_4$ and 0.1 N HCl. Heavy metal concentrations in soils are within the range of those in uncontaminated soils. In comparison of metal contents extracted by 0.1 N HCl and HNO$_3$+HC1O$_4$, less than 10% of the heavy metals are present in the exchangeable fraction. In particular, an pollution index has been proposed to assess the degree of soil contamination. Pollution index in soils are between 0.03 and 0.47 therefore, soils are not polluted with heavy metals. Deep groundwaters within granitic rocks have been evolved into Na$\^$＋/-HCO$_3$$\^$-/ type, whereas other deep groundwaters evolved into Ca$\^$2＋/-HCO$_3$$\^$-/ type. The predominance of Na$\^$＋/ over Ca$\^$2＋/ in deep groundwaters within granitic rocks is a result of dissolution of plagioclase, but for sedimentary and meta-sedimentary rocks, dissolution of calcite is a dominant factor for their hydrogeochemistry. The pH, conductivity and contents of the most dissolved ions in the water increase with depth. Shallow groundwaters, however, are highly susceptible to pollution owing to agricultural activities, considering the fact that high contents of nitrate, chloride and potassium, and high K/Na ratio are observed in some shallow groundwaters. In a thermodynamic approach, most natural water samples are plotted within the stability fields of kaolinite and smectite. Therefore, microcline and other feldspars will alter to form clay minerals, such as kaolinite and smectite. From the modelling for water-rock interactions based on mass balance equation, models accord well with behavior of the ions and results of thermodynamic studies are derived.

• Korean Journal of Food Science and Technology
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• v.37 no.3
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• pp.352-359
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• 2005

Uncertainty involved during determination of vitamin C content in infant formula was quantified by indophenol titration method. Uncertainty sources in measurand, such as purity, weight, final volume of standard, volume of standard solution used for titration, sample weight, final volume of sample, extraction solution used for titration, titration of extraction solution and standard solution by indophenol solution were identified and used as parameters for combined standard uncertainty based on Guide to the expression of uncertainty in measurement (GUM) and Draft EURACHEM/CITAC Guide. Uncertainty parameters of each source in measurand were identified as resolution, reproducibility and stability of chemical balance, standard material purity, repeatability, reproducibility, end point of titration, 1 mL pipet, 5 mL autopipet, and 100 mL mass flask. Each uncertainty component was evaluated by types A and B and included to calculate combined uncertainty. Analytical test result for traceability under laboratorial conditions using Certified Reference Material (CRM) test was certified as $108.4{\pm}1.7mg/100g$, which was within CRM certification range of $114.6{\pm}6.6mg/100g$. Uncertainty test result of vitamin C content of 5 g sampling was $56.7{\pm}2.44mg/100g$. Uncertainty could be reduced by identification of uncertainty sources and components related with vitamin C determination by indophenol titration method and by decreasing uncertainty sources and components.

• Journal of Nutrition and Health
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• v.18 no.4
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• pp.259-271
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• 1985

The purpose of this study was to develop supplementary foods for infants and young children in order to improve their nutritional status. Three formulas composed of rice, soybeans, fish, dry skim milk and sesame in varying proportions were studied. The three formulas, $RS_{1}S_{2}$, $RFS_{1}S_{2}$, and $RMS_{1}S_{2}$, were consisted of Rice(R), Soybean$(S_{1})$, Sesame$(S_{2})$ (60 : 35 : 5) , Rice, Fish(F), Soybean, Sesame (60 : 10 : 25 : 5) , and Rice, Dry Skin Milk (M), Soybean, Sesame (60 : 10 : 25 : 5), respectively. A proximate analysis and amino acid determination were made on the developed formulas. In the animal assay, growth rate, PER and FER were evaluated and biochemical analyses were also carried out. A storage test and the cost evaluation were also conducted. The summarized results are as follows : 1) The proximate composition of the three formulas were 7.3-7.4% of moisture, 15.9-21.5% of crude protein, 7.8-9.6% of crude fat and 2.5-2.8% ash. 2) The result of amino acid analysis showed that the 1st limiting amino acids of $RS_{1}S_{2}$ and $RFS_{1}S_{2}$ were lysine (amino acid score, 76.6) and threonine (amino acid score, 93.3), and that of $RMS_{1}S_{2}$ and the commercially prepared formula were sulfur containing amino acids (amino acid score, 82.0 and 54.4). When the contents of the amino acids of the three formulas were compared with mother's milk and cow's milk, the balance of the amino acid of each formula was superior to mother's milk but inferior to cow's milk. 3) In the animal assay, the growth rate of all groups increased gradually during the experimental period. 4) The C- PER, which was corrected on the basis of the casein PER of 2.5 was 2.99, 3.38 and 3.10 in the $RS_{1}S_{2}$, $RFS_{1}S_{2}$ and $RMS_{1}S_{2}$ respectively. The C- PER of $RFS_{1}S_{2}$ and $RMS_{1}S_{2}$ were Significantly (P<.05) higher than that of the casein. 5) The FER of the casein, $RS_{1}S_{2}$, $RFS_{1}S_{2}$, and $RMS_{1}S_{2}$ were 0.37, 0.39, 0.43 and 0.39, respectively. The FER of $RFS_{1}S_{2}$ and $RMS_{1}S_{2}$ were also significantly (P<.05) higher than that of the casein. 6) The concentrations of hematocrit, hemoglobin, total protein and albumin in the serum of the rats of all groups were not significantly different among groups. 7) The storage stability test showed that the total plate count (TPC), the coliforms count and the bacterial spore count in the ingredients were quiet low. However, after 30 and 60 days storage, the count in $RFS_{1}S_{2}$ increased and were higher at room temperature than refrigerated temperature. 8) In the cost evaluation, the cost of the developed formulas was \1,826-2,626 / kg. This was less than that of the commercially prepared formula (\3,300-4,073 / kg) and that of the imported formula (\4,250-8,720 / kg).