• 한국표면공학회지
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• 제51권3호
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• pp.157-163
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• 2018

The anodic $TiO_2$ layers which are prepared in various anodization conditions exhibit their specific color depending on the thickness of $TiO_2$. In this study, the relationship between the color of $TiO_2$ layer, which is grown by PEO (Plasma electrolytic oxidation), and the thickness of the $TiO_2$ layer is investigated. To evaluate the color change of the $TiO_2$ layer, the value of color ($dE^*ab$) is measured and calculated by spectrophotometer and chromameter. As a result, it is found that $dE^*ab$ values and thickness of $TiO_2$ layers form a linear relationship with meaningful formular. This formula can be helpful to quantify the thickness of the $TiO_2$ layer by the numerical $dE^*ab$ values. In this process, the spectrophotometer shows more precise results than the chromameter dose. If fluoride ions ($F^-$) are included in the electrolyte, it will affect the $dE^*ab$ values of the $TiO_2$. layer. This is against the propensity, which is analyzed by XRD (X-ray diffraction) and XPS (X-ray photoelectron spectroscopy). It is important that the formular suggested in this study provides other metals which can be also anodized with the possibility of quantifying the thickness of the $TiO_2$ layer by the $dE^*ab$ values.

• 한국치위생학회지
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• 제14권4호
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• pp.547-553
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• 2014

Objectives : This research aims to analyze the relationship between the state of mental illness and oral health management of mental patients in mental health care institutions. Methods : The data were randomly selected from 474 patients in mental health care institutions. and analyzed by SPSS WIN 12.0 program. Results : Schizophrenia accounted for 79.5%(337 patients) ; alcohol dependency, 5.3%(25 patients) ; mental retardation, 2.7%(13 patients) ; mental development disorder, 3.0%(14 patients) ; mental delusion and dementia, 7.6%(36 patients). Those who were in 40s had the highest dental caries of 3.95 and the highest remaining teeth of 26.76 were shown in the 20s. The correlation between remaining teeth and mental retardation was the highest, measuring 22.38(p<.05). Those who were in 70s had the serious periodontal condition that accounted for 41.3%(12 patients)(p<.05). The correlation coefficient for all factors-dental caries, remaining teeth, need for scaling, and periodontal condition-between mental illness condition and oral health were all positive(p <.05). The regression analysis resulted in the formula Y(mental health condition)=2.999+0.166(dental aries)-0.028(remaining teeth). Conclusions : Those who had mental illness had very poor and serious dental caries and periodontal diseases, so it is necessary to manage the dental health care for the mentally ill patients.

• Steel and Composite Structures
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• 제25권1호
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• pp.79-92
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• 2017

Initial damage to a stud due to corrosion, fatigue, unexpected overloading, a weld defect or other factors could degrade the shear capacity of the stud. Based on typical push-out tests, a FEM model and theoretical formulations were proposed in this study. Six specimens with the same geometric dimensions were tested to investigate the effect of the damage degree and location on the static behavior and shear capacity of stud shear connectors. The test results indicated that a reduction of up to 36.6% and 62.9% of the section area of the shank could result in a dropping rate of 7.9% and 57.2%, respectively, compared to the standard specimen shear capacity. Numerical analysis was performed to simulate the push-out test and validated against test results. A parametrical study was performed to further investigate the damage degree and location on the shear capacity of studs based on the proposed numerical model. It was demonstrated that the shear capacity was not sensitive to the damage degree when the damage section was located at 0.5d, where d is the shank diameter, from the stud root, even if the stud had a significant reduction in area. Finally, a theoretical formula with a reduction factor K was proposed to consider the reduction of the shear capacity due to the presence of initial damage. Calculating K was accomplished in two ways: a linear relationship and a square relationship with the damage degree corresponding to the shear capacity dominated by the section area and the nominal diameter of the damaged stud. This coefficient was applied using Eurocode 4, AASHTO LRFD (2014) and GB50017-2003 (2003) and compared with the test results found in the literature. It was found that the proposed method produced good predictions of the shear capacity of stud shear connectors with initial damage.

• Applied Biological Chemistry
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• 제40권5호
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• pp.409-415
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• 1997

식품 및 배합사료 첨가제로서 치아민 모노유도체인 치아민 모노로단염이외, 치아민 모노요오드염 치아민 모노브름염 등의 3종류의 용해도를 $40,{\;}50,{\;}60^{\circ}C$에서 구하였고 그 온도에서 4수준(0.5, 1.0, 2.5, 5.0 w/w%)의 물을 첨가한 다음 경시적으로 겉보기 착색속도정수(ka)를 산출하였다. 그리고 산제이외 제제에 대하여는 착색도 가능성을 검토할 목적으로 비교적 조성이 간단한 과립, 정제를 만들어 이것에 3수준(0.5, 1.0, 2.5 w/w%)의 물을 첨가한 후 산제와 동일한 온도에서 경시적으로 착색시험으로부터 ka를 산출하였고, 구배 ka인 직선에 대하여는 회귀분산을 이용하여 직선성의 검정을 행하였다. 실험 범위 내에서는 위험률 5%수준에서 모두 유의한 결과를 얻었다. 과립 및 정제의 착색변화로부터 얻은 ka와 1/T간에 직선적인 관계가 성립하여 Arrhenius식을 만족시켰다.

• 한국물환경학회지
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• 제21권3호
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• pp.277-283
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• 2005

This paper aimed to compare the daily water quality as well as the hydrological data gathered for the past two years (2000 to 2001) between the two influent rivers of Paldang reservoir. The analysis also has been carried out to draw out the factors that affect the water quality at the dam site, where the main drinking water drawing point is located. The relationship between total amount of monthly rainfall and monthly inflow showed $r^2=0.74$ (p<0.05). The highest peak of inflow of influent rivers recorded in August and September (in the year of 2000) and July and August (2001). Average inflows of influent rivers in 2000 and 2001 are calculated at 209.0, 161.5 CMS (Bughangang), 268.6, 148.2 CMS(Namhangang), and 7.8, 5.0 CMS (Gyeongancheon). The formula which was driven from the relationship between inflow and COD load of influent rivers, explained that COD concentration in general increased with the inflow. But during the rainy seasons (July, August, and September), COD concentration decreased according to the increase of inflow. The daily rainfall and COD concentration(or load) during the rainy season (August and September in the year of 2000, July and August in 2001) indicated that the peak of COD load correspond with the rainfall, which decreased sharply after 3 or 4 days. The reason was thought that the high COD load was diluted rapidly by the rain flow. Water temperature, pH and conductivity measured at dam site decreased obviously when the inflow sharply increased. Peak period of total phosphorus concentration coincided with that of inflow. In rainy season, chlorophyll-a concentration decreased obviously as the inflow increased. The reason can be ascribed to the flushing effect caused by the operation of floodgate.

• 한국방재학회 논문집
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• 제9권1호
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• pp.135-144
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• 2009

본 연구에서는 대표단위도가 작성되어 있는 중규모 하천유역을 대상으로 첨두유량을 발생시키는 임계지속기간을 결정하고 임계지속기간과 관련된 수문요소들에 대한 평가를 수행하였다. 임계지속기간과 유역특성인자, 유역응답시간 특성인자 그리고 단위도 특성인자들과의 상관분석을 실시하였다. 분석결과, 재현기간을 제외한 나머지 수문요소(확률강우강도식, 유출량 산정방법, 유효우량 산정방법, 강우시간분포)이 임계지속기간에 영향을 미치는 것으로 판단되었다. 상관분석을 통하여 유역면적, 유로연장, 유로경사, 유역경사가 임계지속기간과 상관성이 높은 것으로 나타났다. 상관성이 높은 유역특성인자와 임계지속기간과의 다중회귀 분석을 실시하고 7가지 형태의 회귀식을 제시하였으며, 유도된 회귀식의 결정계수가 모두 $0.96{\sim}0.97$으로 나타나 매우 높은 상관관계를 갖는 것으로 나타났다.

• 한국수자원학회논문집
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• 제52권9호
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• pp.589-601
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• 2019

최근 수문기상학 분야에서 레이더 강수량을 활용한 응용연구가 활발하게 진행되고 있다. 하지만 레이더 강수량은 경험적인 레이더 반사도-강수강도 관계식을 활용하여 레이더 강수량을 추정하기 때문에 실제 지상에 도달하는 강수량과 정량적인 오차가 필연적으로 발생한다. 따라서 본 연구에서는 레이더 강수량 편의보정을 위하여 Bayesian 추론기법과 일반화 선형모형을 연계하여 불확실성을 고려한 편의보정 매개변수를 산정하였다. 일반화 선형모형을 적용한 레이더 강수량 편의보정 결과는 현재 널리 사용되고 있는 평균보정 기법보다 우수한 통계적 효율기준을 제시하였다. 추가로 지형학적 특성에 따른 편의보정 매개변수의 변동성을 분석하여 고도 및 이격거리에 따른 편의보정 매개변수의 지역화 공식을 제시하였다. 본 연구를 통하여 개발된 레이더 강수량 편의보정 매개변수 산정 및 지역화 결과는 레이더와 관련된 다양한 연구에 활용성이 클 것으로 판단된다.

• 한국재료학회지
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• 제29권8호
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• pp.469-476
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• 2019

A lead-free bulk ceramic having a chemical formula $Ba_{0.8}Ca_{0.2}(Ti_{0.8}Zr_{0.1}Ce_{0.1})O_3$ (further termed as BCTZCO) is synthesized using mixed oxide route. The structural, dielectric, impedance, and conductivity properties, as well as the modulus of the synthesized sample are discussed in the present work. Analysis of X-ray diffraction data obtained at room temperature reveals the existence of some impurity phases. The natural surface morphology shows close packing of grains with few voids. Attempts have been made to study the (a) effect of microstructures containing grains, grain boundaries, and electrodes on impedance and capacitive characteristics, (b) relationship between properties and crystal structure, and (c) nature of the relaxation mechanism of the prepared samples. The relationship between the structure and physical properties is established. The frequency and temperature dependence of the dielectric properties reveal that this complex system has a high dielectric constant and low tangent loss. An analysis of impedance and related parameters illuminates the contributions of grains. The activation energy is determined for only the high temperature region in the temperature dependent AC conductivity graph. Deviation from the Debye behavior is seen in the Nyquist plot at different temperatures. The relaxation mechanism and the electrical transport properties in the sample are investigated with the help of various spectroscopic (i.e., dielectric, modulus, and impedance) techniques. This lead free sample will serve as a base for device engineering.

• 대한한의학원전학회지
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• 제32권2호
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• pp.71-92
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• 2019

Objectives : To examine various ways non-glutinous rice has been applied in different formulas of "Shanghanlun" and the relationship between non-glutinous rice and the formulas' effects. Methods : First, texts that included non-glutinous rice were selected from the "Shanghanlun". Then, they were categorized according to the application of non-glutinous rice, followed by analysis of its relationship with each formula. Results : Most formulas that used non-glutinous rice in raw form when decocting with other ingredients included Shigao. Non-glutinous rice alleviates coldness of Shigao as in the case with Taohuatang where it stops diarrhea. Non-glutinous rice used in Wumeiwan warms the center and boosts Qi and helps the medicinal ingredients to bind when made into pellets. In Guizhitang and Lizhongwan, non-glutinous rice assists Stomach Qi. In Shizaotang, porridge is taken after diarrhea to help quick recovery. To prevent damage of Zheng Qi, Baisan can be mixed with rice water for administration. The level of cathartic effect can be managed through giving cold or hot porridge to the patient according to his/her response to the medicine. Mazirenwan, Mulizexiesan, Banxiasan, Sinisan, Wulingsan are mixed in rice water for administration. It makes it easier to swallow than when mixed with plain water. The application of rice flour is either internal or external. In Zhufutang, where rice flour is parched, it harmonizes the center and stops diarrhea. In Daqinglongtang when there is too much perspiration, warm powder is sprinkled on the skin to stop sweating. Clear porridge in Jiuziyisifang and rice flour in Shechuangzisan were exclusive to "Jinguiyaolue", while Baisan and rice water mixture could only be found in "Shanghanlun". Conclusions : The excavation and research on various ways non-glutinous rice was applied in treatment holds certain meaning in contemporary practice of Korean Medicine where treatment leans heavily on medicinal treatment rather than food, and all ingredients are boiled together in large quantities for most decoctions.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.396-408
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• 2019

The tubes which are applied in jacket platforms as the supporting structure might be collided by supply vessels. Such kind of impact will lead to plastic deformation on tube members. As a result, the ultimate strength of tubes will decrease compared to that of intact ones. In order to make a decision on whether to repair or replace the members, it is crucial to know the residual strength of the tubes. After being damaged by lateral impact, the simply supported tubes will definitely loss a certain extent of load carrying capacity under uniform axial compression. Therefore, in this paper, the relationship between the residual ultimate strength of the damaged circular tube by collision and the energy dissipation due to lateral impact is investigated. The influences of several parameters, such as the length, diameter and thickness of the tube and the impact energy, on the reduction of ultimate strength are investigated. A series of numerical simulations are performed using nonlinear FEA software LS-DYNA. Based on simulation results, a non-dimensional parameter is introduced to represent the degree of damage of various size of tubes after collision impact. By applying this non-dimensional parameter, a simplified formula has been derived to describe the relationship between axial compressive residual ultimate and lateral impact energy and tube parameters. Finally, by comparing with the allowable compressive stress proposed in API rules (RP2A-WSD A P I, 2000), the critical damage of tube due to collision impact to be repaired is proposed.