• 한국주조공학회지
• /
• 제18권6호
• /
• pp.570-577
• /
• 1998

An investigation has been conducted to describe solidification characteristics in Sn-Zn binary system and Sn-Zn-Ag ternary system added by Ag produced by the continuous casting process using heated mold as a basic study for developing Pb-free solder materials. To obtain the continuous casting rods with mirror surface and near net shape at higher casting speed, water flow rates must be increased and mold temperature must be lowered. However, surface tearing in the casting rods occured at lower continuous casting speed while break out occured at higher continuous casting speed even if optimum conditions such as water flow rate and heated mold temperature are determined. Primary ${\alpha}Sn$ and eutectic structure in unidirectioally solidified Sn-Zn alloys were finer with increased casting speed. But, directionality may not be expected for primary Zn in hypereutectic Sn-Zn alloy. It was found that the addition of $0.2{\sim}0.8%$ Ag promoted the growth of primary ${\alpha}Sn$ dendrites. The changes of tensile strength and elongation in Sn-Zn binary alloys were not observed while the increase of tensile strength and the decrease of elongation in Sn-Zn-Ag ternary alloys were observed with increased casting speed.

• 한국안전학회지
• /
• 제14권1호
• /
• pp.78-85
• /
• 1999

The removal characteristics of H$_2$S from IGCC process over the natural manganese ore(NMO) containing several metal oxides($MnO_x$ : 51.85%, $FeO_y$ : 3.86%, CaO : 0.11%) were carried out in a batch type fluidized bed reactor(I.D.=40mm, height=0.8m). The $H_2S$ breakthrough curves were obtained as a function of temperature, initial gas velocity, initial gas concentration, and aspect ratio. The effect of particle size ratio and particle mixing fraction on $H_2S$ removal were investigated with binary system of different particle size. From this study, the adsorption capacity of $H_2S$ increased with temperature but decreased with excess gas velocity. The breakthrough time for $H_2S$ is reduced as the gas velocity is increased which leaded to gas by-passing and gas-solid contacting in a fluidized bed reactor. The results of the binary particle system with different size in batch experimental could predict to improve the behavior of continuous process of $H_2S$ removal efficiency. The natural manganese ore could be considered as potential sorbent in $H_2S$ removal.

• 한국지능시스템학회논문지
• /
• 제12권2호
• /
• pp.135-143
• /
• 2002

본 논문에서는 전류모드 CMOS의 기본회로를 이용해 다치 논리(Multiple Valued Logic) 연산기를 설계하고자 한다. 우선, 2진(binary)FFT(Fast courier Transform)를 확장해 다치 논리회로를 이용해서 고속 다치 FFT 연산기를 구현하였다. 다치논리회로를 이용해서 구현한 FFT연산은 기존의 2치 FFT과 비교를 해 본 결과 트랜지스터의 수를 상당히 줄일 수 있으며 회로의 간단함을 알 수가 있었다. 또한, 캐리 전파 없는 가산기론 구현하기 위해서 {0, 1, 2, 3}의 불필요한(redundant) 숫자 집합을 이용한 양의 수 표현을 FFT회로에 내부적으로 이용하여 결선의 감소와 VLSI 설계시 정규성과 규clr성으로 효과적이다. FFT 승산을 위해서는 승산기의 연산시간과 면적을 다치 LUT(Look Up Table)로 이용해 승산의 역할을 하였다. 마지막으로 이진시스템(binary system)과의 호환을 위해 다치 하이브리드형 FFT 프로세서를 제시하여 2진 4치 부호기와 4치 2진 복호기 및 전류모드 CMOS회로를 사용하여 상호 호환성을 갖도록 설계를 하였다.

• 한국콘텐츠학회논문지
• /
• 제15권8호
• /
• pp.366-374
• /
• 2015

본 연구는 공공부조를 지원받고 있는 대상자를 중심으로 자살생각에 영향을 미치는 요인이 무엇인지 살펴보았다. 이를 위하여 한국보건사회연구원과 서울대학교 사회복지연구소에서 조사한 한국복지패널(Korea Welfare Panel Study) 7차년도(2012년) 자료를 사용하였으며, 분석방법은 자살생각에 대한 영향의 정도를 파악하기 위해 이항 로짓모형을 이용한 회귀분석(binary logistic regression analysis)을 실시하였다. 분석 결과 중졸인 경우, 기혼인 경우, 자아존중감이 높을수록, 공공부조 만족도가 높을수록 자살생각을 할 가능성이 낮은 것으로 나타났다. 또한 우울이 있는 경우, 중년층인 경우 자살생각을 할 가능성이 높았다. 빈곤층에게 신체적, 심리적 요인만이 아닌 공공부조 만족도 역시 자살생각에 영향을 미칠 수 있다는 것을 증명하였다. 따라서 지원을 받는 대상자들의 만족도를 측정하는 것도 자살생각에 영향을 미치는 중요한 요인 중 하나일 수 있음을 시사한다.

• 대한화학회지
• /
• 제41권2호
• /
• pp.63-68
• /
• 1997

등유전성 용매내에서 분자간 상호작용과 액체구조에 대한 정보를 얻기 위하여 양성자성 용매(protic solvent)인 ROH(R=Me, Et)와 양극성 비양성자성 용매(dipolar aprotic solvent)인 MeCN,$Me_2CO,\;MeNO_2(or EtNO_2)$간의 이성분 혼합물에서 각 성분의 분몰 용해엔탈피를 열량계법으로 측정하고 이를 이용하여 mixing과정에 대한 잉여엔탈피를 결정하였다. 이로부터 두 성분간의 수소결합 세기는$ROH-ROH>ROH-Me_2CO>ROH-MeCN>ROH-MeNO_2(or EtNO_2)$순으로 감소하며, ROH의 수소결합주게 산도(hydrogen bond donor acidity)는 MeOH>EtOH의 순으로 감소하며 이로부터 이성분 액체혼합물이 형성될 때의 에너지론(energetics)에 미치는 가장 강한 상호작용이 특별한 수소결합에 기인됨을 알 수 있었다.

• 천문학논총
• /
• 제30권2호
• /
• pp.205-209
• /
• 2015

The Eclipsing Binaries Minima (BIMA) Monitoring Project is a CCD-based photometric observational program initiated by Bosscha Observatory - Lembang, Indonesia in June 2012. Since December 2012 the National Astronomical Research Institute of Thailand (NARIT) has joined the BIMA Project as the main partner. This project aims to build an open-database of eclipsing binary minima and to establish the orbital period of each system and its variations. The project is conducted on the basis of multisite monitoring observations of eclipsing binaries with magnitudes less than 19 mag. Differential photometry methods have been applied throughout the observations. Data reduction was performed using IRAF. The observations were carried out in BVRI bands using three different small telescopes situated in Indonesia, Thailand, and Chile. Computer programs have been developed for calculating the time of minima. To date, more than 140 eclipsing binaries have been observed. From them 71 minima have been determined. We present and discuss the O-C diagrams for some eclipsing binary systems.

• 한국보건간호학회지
• /
• 제21권2호
• /
• pp.125-133
• /
• 2007

Purpose: To identify the compliance level with therapeutic regimen among patients with hypertension residing in rural communities. Method: A descriptive-retrospective research design was employed. One hundred patients with hypertension using 8 Primary Health Care Posts under W Public Health Center were randomly recruited on the basis of being over 35 years of age. After obtaining written consent, the patients underwent direct interviews with a structured questionnaire carried out by 8 public health practitioners. Descriptive statistics and binary logistic regression were utilized. Results: In a binary logistic regression model adjusted for age, sex, education, income, and occupation, those who were receiving medication (OR=5.34), were undergoing a weight control program (OR=4.45), restricted alcohol (OR=9.93), or smoking cessation (OR=25.59) as recommended by medical or health professionals were more compliant (p<.05) while those under a low salt diet, exercise, and stress management were not significant statistically (p>.05). Conclusions: Further research should be conducted to validate these findings so as to facilitate the development of nursing intervention strategies for improving the compliance of hypertensive patients in respect to medication and life style modification.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.192.2-192.2
• /
• 2014

Among various dopant candidates, nitrogen (N) atoms are considered as the most effective dopants to improve the diverse properties of graphene. Unfortunately, recent experimental and theoretical studies have revealed that different N-doped graphene (NGR) conformations can result in both p- and n-type characters depending on the bonding nature of N atoms (substitutional, pyridinic, pyrrolic, and nitrilic). To overcome this obstacle in achieving reliable graphene doping, we have carried out density functional theory calculations and explored the feasibility of converting p-type NGRs into n-type by introducing additional dopant candidates atoms (B, C, O, F, Al, Si, P, S, and Cl). Evaluating the relative formation energies of various binary-doped NGRs and the change in their electronic structure, we conclude that B and P atoms are promising candidates to achieve robust n-type NGRs. The origin of such p- to n-type change is analyzed based on the crystal orbital Hamiltonian population analysis. Implications of our findings in the context of electronic and energy device applications will be also discussed.

• Structural Engineering and Mechanics
• /
• 제91권3호
• /
• pp.279-289
• /
• 2024

The purpose of this study is to represent a useful alternative for the preliminary seismic vulnerability assessment of existing reinforced concrete buildings by introducing a statistical approach employing the binary logistic regression technique. Two different predictive statistical models, namely full and reduced models, were generated utilizing building characteristics obtained from the damage database compiled after 1999 Düzce earthquake. Among the inspected building parameters, number of stories, overhang ratio, priority index, soft story index, normalized redundancy ratio and normalized lateral stiffness index were specifically selected as the predictor variables for vulnerability classification. As a result, normalized redundancy ratio and soft story index were identified as the most significant predictors affecting seismic vulnerability in terms of life safety performance level. In conclusion, it is revealed that both models are capable of classifying the set of buildings being severely damaged or collapsed with a balanced accuracy of 73%, hence, both are able to filter out high-priority buildings for life safety performance assessment. Thus, in this study, having the same high accuracy as the full model, the reduced model using fewer predictors is proposed as a simple and viable classifier for determining life safety levels of reinforced concrete buildings in the preliminary seismic risk assessment.

• Communications for Statistical Applications and Methods
• /
• 제14권1호
• /
• pp.1-9
• /
• 2007

A three-state Markov logistic regression model is suggested to forecast the probability of tomorrow's precipitation based on the current meteorological situation. The suggested model turns out to be better than Markov regression model in the sense of the mean squared error of forecasting for the rainfall data of Seoul area.