• 대한인간공학회지
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• 제34권1호
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• pp.19-27
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• 2015

Objective: The aim of this study is to investigate how well eye movement times in visual target selection tasks by an eye input device follows the typical Fitts' Law and to compare vertical and horizontal eye movement times. Background: Typically manual pointing provides excellent fit to the Fitts' Law model. However, when an eye input device is used for the visual target selection tasks, there were some debates on whether the eye movement times in can be described by the Fitts' Law. More empirical studies should be added to resolve these debates. This study is an empirical study for resolving this debate. On the other hand, many researchers reported the direction of movement in typical manual pointing has some effects on the movement times. The other question in this study is whether the direction of eye movement also affects the eye movement times. Method: A cursor movement times in visual target selection tasks by both input devices were collected. The layout of visual targets was set up by two types. Cursor starting position for vertical movement times were in the top of the monitor and visual targets were located in the bottom, while cursor starting positions for horizontal movement times were in the right of the monitor and visual targets were located in the left. Results: Although eye movement time was described by the Fitts' Law, the error rate was high and correlation was relatively low ($R^2=0.80$ for horizontal movements and $R^2=0.66$ for vertical movements), compared to those of manual movement. According to the movement direction, manual movement times were not significantly different, but eye movement times were significantly different. Conclusion: Eye movement times in the selection of visual targets by an eye-gaze input device could be described and predicted by the Fitts' Law. Eye movement times were significantly different according to the direction of eye movement. Application: The results of this study might help to understand eye movement times in visual target selection tasks by the eye input devices.

• 산업진흥연구
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• 제3권2호
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• pp.1-8
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• 2018

본 연구에서는 탄화수소 개질을 위한 예비 개질기에서 에탄의 반응 메커니즘과 이에 적합한 반응속도식에 대한 연구를 수행하였다. 반응 mechanism 분석을 통해 ethane의 개질 반응 중 (CO2+H2,C2H6+H2,C2H6+H2O)3개의 반응이 진행되는 것을 확인할 수 있었으며, 각각의 반응 속도 (CO2+H2($r=3.42{\times}10-5molgcat.-1\;s-1$), C2H6+H2($r=3.18{\times}10-5mol\;gcat.-1s-1$), C2H6+H2O($r=1.84{\times}10-5mol\;gcat.-1s-1$)) 를 구하였다. 이를 통해 C2H6+H2O반응이 rate determining step (RDS)임을 확인하고, Langmuir-Hinshelwood model (L-H model)을 통해 이 반응의 반응식을 r=kS*(KAKBPC2H6PH2O)/(1+KAPC2H6+KBPH2O)2 (KA=2.052,KB=6.384,$kS=0.189{\times}10-2$)로 나타낼 수 있었다. 이렇게 얻어진 반응식은 반응 메커니즘을 고려하지 않고 유도된 power rate law와 비교하였으며, power rate law는 좁은 농도 변화 영역 (ethane 약 2.5-4%, water 약 60-75%)에서는 비교적 유사한 fitting이 이루어졌지만, 넓은 농도 변화영역에서는 반응 mechanism을 토대로 얻은 L-H model 반응식이 실험값과 더 유사한 값을 보이는 것을 확인하였다.

• Journal of Radiation Protection and Research
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• 제17권1호
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• pp.21-30
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• 1992

KCCH cyclotron neutron(30cCy/min) 및 $^{60}Co\;{\gamma}-ray(210cGy/min)$를 시험관내의 정상인체 말초혈액임파구에 조사하여 염색체이상(dicentric 및 centric ring)을 관찰하고 이의 선량-반응관계식을 linear model$(Y=K_1D+a)$, power-law model$(Y=K_2D^n)$, quadratic model$(Y=K_3D^2)$ 및 linear-quadratic model$(Y={\alpha}D+{\beta}D^2)$을 사용하여 구하고 이들 model중 염색체이상의 측정치와 가장 일치하는 관계식을 근거로 하여 ${\gamma}-ray$에 대한 neutron의 relative biological effectiveness (RBE)를 산출하였다. 염색체 이상(dicentric plus centric ring)의 발생분포는 ${\gamma}-ray$의 경우 linear model(P=0.067)을 제외한 power-law model$[Y=(5.81{\pm}1.96){\times}10^6D^{1.93+0.06},\;P=0.931]$, quadratic model$[Y=(3.91{\pm}0.09){\times}10^{-6}D^2,\;P=0.972]$ 및 linear-quadratic model $[Y=(6.55{\pm}6.83){\times}10^{-5}D+(3.72{\pm}0.22){\times}10^{-6}D^2$ P=0.922]에 적합하였다 neutron의 경우 linear model $(Y=(6.12{\pm}0.17){\times}10^{-3}\;D-0.22,\;P=0.987]$에 가장 일치하였고 quadratic model (P<0.005)을 제외한 power-law model $[Y=(5.36{\pm}3.02) {\times}10^{-4}D^{1.42+0.11},\;P=0.601]$ 및 linear-quadratic model $[Y=(2.43{\pm}0.70){\times}10^{-3}D+(1.21{\pm}0.39){\times}10^{-7}D^2,\;P=0.415]$에 비교적 적합하였다. 세포당 0.1-1.5개의 염색체이상을 나타내는 neutron의 ${\gamma}-ray$에 대한 RBE는 $2.714{\pm}0.408$이었다.

• 대한화학회지
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• 제35권2호
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• pp.111-118
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• 1991

기체 상태의 오존(0.5 torr)과 이산화황간의 반응속도를 연구하였다. 이산화황은 7∼22 torr 의 압력범위에서 90∼155$^{\circ}$C의 온도영역에서 반응시켰다. 오존과 이산화황의 반응속도는 이산화탄소와의 반응보다 빨리 진행되었다. 오존과 이산화황의 반응속도식은 -d(O$_3 )/dt = k _0 (SO _2 )(M)(O _3)+2k _1(SO_2 )(O _3$)였다. 이 속도식의 첫 항은 3분자 반응으로 낮은 온도에서 우세하게 진행되었으며, 속도상수 k$_0 =(9.35{\pm}8.6){\times}10^9e^{-(11.05{\pm}2.04)kcal/RT}(M^{-2}s^{-1}$)이다. 속도식의 두번째 항은 2분자 열분해 반응으로부터 유도된 주된 반응으로 속도상수 k$_1=(1.53{\pm}1.5){\times}10^{11}e^{-22.7 kcal/RT}$이다. 전 반응차수는 주로 2차 반응이며 3차 반응과 복합반응으로 진행되었다.

• 대한인간공학회지
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• 제31권5호
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• pp.647-655
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• 2012

Objective: The purpose of this study was to confirm difference between angular foot movement time and existing foot Fitts' law predicting times, and to develop the angular foot Fitts' law in the foot tapping task. Background: Existing studies of foot Fitts' law focused on horizontal movement to predict the movement time. However, when driving a car, humans move their foot from the accelerator to the brake with a fixed heel. Therefore, we examined the experiment to measure angular foot movement time in reciprocal foot tapping task and compared to conventional foot Fitts' law predicting time. And, we developed the angular foot Fitts' law. Method: In this study, we compared the angular foot movement time in foot tapping task and the predicted time of four conventional linear foot Fitts' law models - Drury's foot Fitts' law, Drury's ballistic, Hoffmann's ballistic, Hoffmann's visually-controlled. 11 subjects participated in this experiment to get a movement time and three target degrees of 20, 40, and 60 were used. And, conventional models were calculated for the prediction time. To analyze the movement time, linear and arc distance between targets were used for variables of model. Finally, the angular foot Fitts' law was developed from experimental data. Results: The average movement times for each experiment were 412.2ms, 474.9ms, and 526.6ms for the 89mm, 172mm, and 253mm linear distance conditions. The results also showed significant differences in performance time between different angle level. However, all of conventional linear foot Fitts' laws ranged 135.6ms to 401.2ms. On the other hand, the angular foot Fitts' law predicted the angular movement time well. Conclusion: Conventional linear foot Fitts' laws were underestimated and have a limitation to predict the foot movement time in the real task related angular foot movement. Application: This study is useful when considering the human behavior of angular foot movement such as driving or foot input device.

• 한국수학사학회지
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• 제36권2호
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• pp.21-34
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• 2023

Spherical trigonometry refers to the geometry related to spherical triangles. It has been an important tool for studying astronomy since ancient times. In trigonometry, concepts such as trigonometric functions naturally emerge from the relationship between arcs and chords of a circle. In this paper, we briefly examine the origin of spherical trigonometry. To introduce the basics of spherical trigonometry, we present fundamental and important theorems such as Menelaus's theorem, the law of sines and the law of cosines on a sphere, along with their proofs. Furthermore, we discuss the educational value and potential applications of spherical trigonometry.

• 대한수학교육학회지:수학교육학연구
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• 제22권2호
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• pp.293-309
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• 2012

자연수의 곱셈 계산법은 초등학교 수학의 가장 기본적인 주제 중 하나이며, 계산법의 숙달과 계산 원리의 이해는 중요한 교육 목적이다. 이 논문에서는 우리나라, 미국, 싱가포르, 일본의 초등학교 수학교과서의 관련 단원을 분석 비교하여 곱셈 계산 지도에 대한 유용한 교수학적 시사점을 얻는 것을 목적으로 한다. 분석 결과, 세 수의 곱셈, '${\times}10$'의 지도, '${\times}$(몇십)'의 지도에서 나라별로 차이가 나타난다는 점이 확인되었다. 이러한 분석 결과를 토대로 하여 시사점을 제안하였다.

• 소성∙가공
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• 제4권2호
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• pp.159-168
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• 1995

The torsion tests in the range of $550~800^{\circ}C$, $5.0{\times}10^{-3}~5.0{\times}10^0/sec$ were performed to study the effects of strain rate$(\.{\varepsilon})$ and temperature(T) on the hot strength of Cu-Zn alloy. High temperature flow stresses of this alloy increased with increasing $\.{\varepsilon}$ and/or decreasing T, and than the more grain refinement could be obtained. The flow curves exhibited a peak followed by a steady steady state regime as a result of dynamic recrystallization. The hot strength dependence of $\.{\varepsilon}$ and T was described by a hyperbolic sine law, $\.{\varepsilon}=A(sinh0.017{\sigma})^4.81$exp(-216KJ/mol). Hot strength could be reduced at the arbitary condition, $\.{\varepsilon}$ and T, by constitutive parameter Z(Zenner-Hollomon parameter), $Z=A(sinh{\alpha}{\sigma})^n=\.{\varepsilon}$exp(Q/RT).

• 한국환경보건학회지
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• 제30권2호
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• pp.133-139
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• 2004

The objective of this study was to investigate the destruction efficiency and to determine the fundamental parameters of oxidation kinetics under the supercritical water(SCW) condition. Target material was cephradine, toxic and antibiotic material, in the pharmaceutical wastewater. For this purpose, the effect of reaction temperature and oxidant were investigated on the destruction efficiency of cephradine. And the oxidation kinetics of cephradine was derived by using a empirical power-law model. The experiment was carried out in a cylindrical batch reactor made of Hastelloy C-276 which was endurable high temperature and pressure. The destruction efficiency of cephradine increased with increment of the temperature and reaction time. Also the type of oxidants was effected and oxidants(Air and $H_2O$$_2$) were enhanced the destruction efficiency. The global oxidation kinetics for cephradine has led to two rate expressions according to type of oxidant. - In the presence of air oxidant: Rate=k. $e^{-Ea}$RT/(Ceph.)$^{1.0}$ ( $O_2$)$^{0.51}$$\pm$0.05(k=3.27${\times}$$10^{5}$ sec. Ea=63.25 kJ/mole) - In the presence of $H_2O$$_2$ oxidant : Rate=kㆍ $e^{-Ea}$RT/(Ceph.)$^{1.0}$ ($H_2O$$_2$)$^{0.62}$$\pm$0.02(k=2.76${\times}$$10^4$/sec. Ea=47.65 kJ/mole)ole))

• 한국안전학회지
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• 제32권3호
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• pp.141-150
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• 2017

A rapid increase in traffic accidents involving senior vehicle occupants has been an issue in Korea because of the aging of the population occurring at one of the fastest rates in the world; unfortunately, few studies beyond several looking at the effect of senior occupants on the level of accident injury severity can be found in the literature. A Multinomial logit model was estimated with Newton-Raphson algorithm to perform bias-reducing penalized likelihood optimization. Model covariates integral to developing the model were included, but the main focus was on the interaction of seating position and injury to senior vehicle occupants. It was found that the likelihood of an accident resulting in a fatality increased: 2.2 times for the driver seat, 2.7 times for the front passenger seat, and even 6.7 times for the rear seat. A mandatory seatbelt law to be extended to the rear seat needs to pass the assembly as soon as possible, and government, industry, and safety groups should be encouraged to join forces to strongly carry out targeted campaigns for the wearing of seatbelts in all vehicle seats to enhance the safety of senior occupants as well as other occupants who are vulnerable to road traffic accidents.