• 한국경영과학회지
• /
• 제19권1호
• /
• pp.113-122
• /
• 1994

This study proposes a new procedure to find an initial solution to reduce the number of iterations of goal programming. The process of computing an initial solution is divided into two steps in this study. Decision variables which satisfy feasibility using Gaussian eliminations construct an initial solution reducing the iterations in the first step. It uses LHS as a tool that decision variables construct an initial solution. The initial solution which is constructed by the first step computes the updated coefficient of the objective function in the second step. If the solution does not satisfy the optimality, the optimal solution using the Modified Simplex Method is sought. The developed method doesn't reduce the overall computing time of goal programming problems, because time is more required for the process of constructing an initial solution. But The result of this study shows that the proposed procedure can reduce the large number of iterations in the first step effectively.

• 설비공학논문집
• /
• 제20권8호
• /
• pp.534-540
• /
• 2008

In this paper, the optimal bang-bang control problem of an air-conditioning system with slab thermal storage was formulated by gradient method. Furthermore, the numeric solution obtained by gradient method algorithm was compared with the analytic solution obtained on the basis of maximum principle. The control variable is changed uncontinuously at the start time of thermal storage operation in an analytic solution. On the other hand, it is showed as a continuous solution in a numeric solution. The numeric solution reproduces the analytic solution when a tolerance for convergence is applied severely. It is conceivable that gradient method is effective in the analysis of the optimal bang-bang control of the large-scale system like an air-conditioning system with slab thermal storage.

• Journal of Biosystems Engineering
• /
• 제15권4호
• /
• pp.328-338
• /
• 1990

The objective of this study was to develop automatic systems of nutrient solution management for optimal nutrient solution environment and labor saving in water culture which enables factory crop production. In this study, an automatic control system and its driving program are developed to prepare, supply, and recover nutrient solution and to keep the optimal solution concentration level using microcomputers. Based on this study, the following conclusions are obtained: 1. The concentration measured by the system using oscillating circuit designed and built in this study, gave good agreements with the actual nutrient solution. 2. In water culture, the period of 12 hours for measuring concentration, pH, and temperature of the nutrient solution was optimum. Addition of control solution due to the decrease of the nutrient solution concentration is required in every 3 to 5 days. 3. It is estimated that the period of the whole solution change is 15 days, however, further research is needed to assure it. In addition, this period must be shortened in the future. 4. Both the hardware and software of the developed optimal nutrient solution control system in the water culture are working very well, however, it is necessary to develop a more economical one-chip micro controller to substitute for the microcomputer.

• 대한기계학회논문집B
• /
• 제28권1호
• /
• pp.81-88
• /
• 2004

In this study, heat and mass transfer characteristics of five components solution (LiBr＋Lil＋LiNO$_3$＋LiCl＋$H_2O$) which could be substituted for commonly used LiBr solution are tested using a helical absorber. The arrangement of helical-typed heat exchangers allows to make the system more compact as compared to conventional one. The effects of experimental parameters, such as the solution flow rate, cooling water, solution temperature, solution concentration and surfactant have been investigated in view of the heat and mass transfer. The results of the experiment of heat and mass transfer performance show that five components solution should have 2％ higher concentration fur equal absorption capacity of LiBr solution. But considering that five components solution have higher solubility than LiBr solution about 4％ high concentration, five components solution could be applied to a small sized water cooled or air cooled absorption chiller/heater. The increase of heat and mass transfer coefficient by surfactant addition is about 25∼30％ and 23∼40％ respectively.

• 한국작물학회:학술대회논문집
• /
• 한국작물학회 2017년도 9th Asian Crop Science Association conference
• /
• pp.212-212
• /
• 2017

This experiments were conducted to evaluate the influence of Chlorella culture solution on seed germination of perennial ryegrass seeds. Chlorella are known to contain different bioactive compounds. In present research work, Chlorella culture solution using liquid manure as medium have been used to study their effects on germination and root length. The study conducted a germination experiment in petri-dishes. Four treatments were compared: non-treated control treated with distilled water, Chlorella culture solution and Chlorella culture filtrate, and liquid manure. The germination percentage of perennial ryegrass seeds was highest in the Chlorella culture solution treatment. Days required for 50, 70% seed germination was the fast in Chlorella culture solution and the Chlorella culture filtrate treatment. Root length of perennial ryegrass seeds was long by 1~2cm in the Chlorella culture solution compared with no treated control. The germination index of perennial ryegrass seeds was high by 180~202% in the Chlorella culture solution treatment compared to no treatment. Chlorella culture solution and the Chlorella culture filtrate have shown stimulatory effects in germination and development of root. Use of Chlorella culture solution and the Chlorella culture filtrate can be recommended to farmers as a ecofriendly practice for better germination and growth. Present research work reveals that Chlorella contain certain growth promoting substances which enhances seed germination.

• Corrosion Science and Technology
• /
• 제4권1호
• /
• pp.19-22
• /
• 2005

Two Au-Ag-Cu-Pd dental casting alloys (Au:12% and 20%) used. The test solutions used 0.9 % NaCl solution (isotonic sodium chloride solution), 0.9 % NaCl solution containing 1 % lactic acid, and 0.9 % NaCl solution containing 1 % lactic acid and 0.1 mol $dm^{-3}$ $Na_2S$. The surface of two samples in three sample solutions was not natural discoloration during one year. The alloy containing 12 % gold was easily alloyed and the composition was uniform comparing with the alloy containing 20 % gold. The rest potentials have not a little effect after three months. The kinds of metals could not definitely from the oxidation and reduction waves of metal on the cyclic voltammograms. The dissolutions of gold and palladium were 12 % Au sample in the 0.9 % NaCl solution containing 1 % lactic acid and 0.1 mol $dm^{-3}$ $Na_{2}S$. The pH of solution had an affect on dissolution of copper, and sulfur ion had an affect on dissolution of silver. The copper dissolved amount from 20 % gold sample was about 26 times comparing with that of 12 % gold sample in the 0.9 % solution containing 1 % lactic acid. Corrosion products were silver chloride and copper chloride in NaCl solution, and silver sulfide and copper sulfide in NaCl solution containing $Na_{2}S$.

• Restorative Dentistry and Endodontics
• /
• 제15권1호
• /
• pp.129-139
• /
• 1990

In order to determine if GK-101E(N-monochloro-DL-2-aminobutyrate) solution was effective in the removal of carious dentin, this study was conducted on 75 extracted human carious teeth. GK-101E solution was compared in effectiveness to saline solution.75 extracted human carious teeth were randomly assigned to two groups accordingly : (1) 50 teeth were treated with GK-101E solution : and (2) 25 teeth were treated with saline solution. Teeth in each group were divided into the medium or medium-hard consistency. Treatment consisted of directing the pulsating stream of each coded test solution utilizing the Caridex$^{TM}$ Caries Removal System against the carious surface for 4 mimutes. One operator treated all teeth with corded solution, and four investigators scored on the treated teeth based on visual examination and tactile evaluation with a dental explorer in conjunction with staining method with Caries Detector$^{TM}$ The results were as follows : 1. All groups showed various effect of carious dentin removal. 2. GK-101E solution was statistically superior to physiologic saline solution in the removal of carious dentin, regardless of carious consistency. 3. GK-101E solution in the medium-hard consistency was statistically superior to that in the medium consistency in the caries removal(p=0.001). 4. Saline solution in the medium consistency was equivalent to that in the medium-hard consistency in caries removal(p>0.1).

• Journal of Korean Biological Nursing Science
• /
• 제17권2호
• /
• pp.150-158
• /
• 2015

Purpose: This study aimed to evaluate the effects of gargling with S-solution and gargling with A-solution on salivary pH, coated tongue, and dental plaque index in preschool children. Methods: Non-equivalent control group pretest-posttest design was used to select the participants. 99 preschool children were divided into three groups. Dependent variables were recorded at baseline, 30 minutes, and 7 days after the first treatment was given. The data were analyzed using $X^2$-test, ANOVA, and repeated measures of ANOVA. Results: There were no significant differences in dependent variables in pre-test. However, the salivary pH in the S-solution group had significantly increased after 30 minutes (p<.05) and then again 7 days (p<.01) after the first treatment. Also, the S-solution and A-solution groups had greater decrease in dental plaque index after 30 minutes and again 7 days after the first treatment (p<.001) than the control group. With respect to coated tongue, there were no significant differences among the three groups. Conclusion: The results of this study indicate that essential oil gargling after brushing is helpful in improving oral health due to auxiliary oral hygiene effects with natural products. Specifically, gargling with S-solution is more effective than A-solution on oral health in preschool children by neutralizing salivary pH and reducing dental plaque index.

• Journal of Positioning, Navigation, and Timing
• /
• 제3권3호
• /
• pp.117-122
• /
• 2014

In CDGPS, ambiguity resolution is determined by the performance of a floating solution, and thus, the performance needs to be improved. In the case of precise positioning at a stationary position, the batch method using multiple measurements is used for the accuracy improvement of a position. The position accuracy performance of a floating solution is outstanding, but it has a problem of high computation cost because all measurements are used. In this study, to improve the floating solution performance of the initial static user in CDGPS, a floating solution method using a recursive filter was implemented. A recursive filter estimates the position solution of the current epoch using the position solution of up to the previous epoch and the pseudorange measurement of the current epoch. The computation cost of the floating solution method using a recursive filter was found to be similar to that of the epoch-by-epoch method. Also, based on actual GPS signals, the floating solution performance was found to be similar to that of the batch method. The floating solution using a recursive filter could significantly improve the performance of the prompt initial position and ambiguity resolution of the initial static user.

• Applied Microscopy
• /
• 제23권2호
• /
• pp.1-10
• /
• 1993

The effect of electrolyte on the extraction replicas of the precipiates in 3% Si steel was investigated. Three Kinds of electrolyte, 2% Nital solution (2% nitric acid+methanol; acid solution),, Sodium Citrate solution (5% sodiumcitrate+1% KBr+0.5KI+$H_{2}O$; aqueous neutral solution) and 10% AA solution (10% acetylacetone+ 1% tetramethylammoniumchloride+methanol; non-aqueous neutral solution), were compared. The preciptiates in 3% Si steel were dissolved in 2% Nital, but they were not dissolved in the Sodium Citrate and 10% AA solution. In Sodium Citrate solution, however, large second artifacts were introduced during sample preparation. Therefore 10% AA solution was found to be most useful for the preparation of extraction replica. The electrolysis condition of a matrix and precipitates were also checked by the measurement of potential-current curve in 10% AA solution. The matrix was electrolyzed at -400mV with respect to SCE(Saturated Calomel Electrode). In contrats precipitates were electrolyzed above 300mV. Precipitates were respected to be stable in 10% AA solution in the range of $-380mV{\sim}-300mV$ usually used to prepare extraction replicas.