PURPOSES : This study investigates the effects of three different three-color arrow traffic light operations on right-turn vehicles at intersections in Busan Metropolitan City. METHODS : Intersections in this study were categorized as general intersections (Type 1), intersections with right-turn pockets (Type 2), and intersections with scramble crosswalks (Type 3), and were investigated in terms of the efficiency (i.e., control delay) and safety (i.e., number of conflicts) of right-turn vehicles by employing VISSIM 2023 and SSAM3. RESULTS : From a mobility perspective (i.e., control delay), the protected/permitted operation outperformed the other two methods at the three types of intersections. The protected operation, similar to the results of the protected/permitted operation, was also superior to the permitted operation in terms of safety (i.e., number of conflicts). CONCLUSIONS : Protected/permitted operation has been proven to be a more efficient and safer measure than other operation methods for alleviating the problems of protected right-turn operation, which is currently implemented without three-color arrow traffic lights.

This article reports on an experimental study that investigated the effects of different conditions of listener backchannels on the fluency of L2 speakers. The participants were 15 advanced Chinese learners of Korean who performed oral tasks in three different backchannel conditions: (1) verbal + nonverbal (V+NV), (2) nonverbal-only (NV), and (3) no backchannels (NB). The verbal backchannels included “[ŋ~] (Non lexical verbal form)”, “[ne]”, “[ɑ]”, “[ɨm]” while the nonverbal backchannels involved head nodding. Fluency was assessed via three temporal measures: Rate A, Rate B and MLR. The data was statistically analyzed using SPSS 25 package. The results showed that 15 Chinese participants in the NV condition were more fluent than in the V+NV or NB conditions. However, no significant differences were found between the V+NV and NB conditions. These results suggest that nonverbal backchannels may facilitate the fluency of advanced Chinese learners of Korean during oral tasks depending on the nature of backchannel use in their L1 and sociocultural environments. The present research theoretically broadens the scope of both fluency and backchannel studies and provides valuable data and methods for empirical studies on backchannels to Korean.

The purpose of this study is to evaluate seismic performances of a modular house system developed by a simple 4-clip fastening method and double metal assembly made of lightweight metals. In order to evaluate structural and non-structural seismic performances of the system. Shaking table test was carried out with full-scale modular units, and a nonlinear pushover analysis was performed to obtain suitable seismic responses for story drifts, displacements, force resistances and dynamic properties of the system. Through 3D analysis and shaking table test, the current method of lightweight modular metal unit assembly and systems with seismic performance of a 4-clip fastening type modular house were demonstrated safe and effective to seismic design.

For this study, we established a system for the CPU cooling performance evaluation and conducted performance tests on air-cooling and water-cooling to understand the effect of the CPU cooling method on performance. For the performance evaluation, the test chamber and water-cooling system were set up, the workload S/W was selected, and a case file was created. In the case of the air-cooling, the CPU temperature is sensitively affected by the outside air temperature, the direction of the board installation, and the influence of the airflow formed around it, and may cause a lot of fluctuations in the CPU temperature. When the water-cooling system was applied, the CPU temperature decreased from 75℃℃ to 37℃ compared to the air-cooled type under the test conditions of 28.5℃ and 3LPM cooling water supply temperature and flow rate. As the CPU clock speed increased due to the decrease in temperature, it was found that the job execution time was reduced by 15~23%. In the future, it is expected that using this performance evaluation environment established through this study will enable us to easily conduct test evaluations for various processors, cooling methods, and changes in operating conditions.

PURPOSES : The purpose of this study is to suggest a thermal expansion coefficient measurement method using an embedded strain transducer (EST) and vibrating wire gauge (VWG), as well as to evaluate the reliability of the proposed methods by comparing them with the AASHTO T 336-10 standard method. METHODS : To apply the AASHTO 336-10 test method, which is the criterion for reliability evaluation, a reference specimen using stainless steel (sus304) is manufactured, and a thermal expansion coefficient of 17.308με/°C is obtained based on ISO regulations. Using the reference specimen, the correction factor of the thermal expansion coefficient measurement equipment is measured to be 2.93με/°C, and using this value, the thermal expansion coefficient of the mortar specimen containing the embedded gauges is measured accurately. The reliability of the proposed experimental method is evaluated by measuring the thermal expansion coefficient of the embedded gauge with temperature compensation and then comparing it with that of the reference specimen. RESULTS : The coefficient of thermal expansion of the mortar specimen is measured to be 12.423με/°C based on AASHTO 336-10, 11.963με/°C using the EST method, and 12.522με/°C using the VWG method. Based on the results obtained using the AASHTO method, the embedded gauges show a difference of 1%~3% in terms of the average results, as well as a difference in the standard deviation of 0.059~0.186. Therefore, our level of confidence in the thermal expansion coefficient experiment using the embedded gauges is high. CONCLUSIONS : When using the AASHTO 336-10 test method, the thermal expansion coefficient should be obtained by measuring the length change of the specimen; however, some engineering judgment of the experimenter is required when the measurement values fluctuate during the temperature stabilization period. In the thermal expansion coefficient test using embedded gauges (EST and VWG), temperature compensation must be performed. Furthermore, it is assumed that the temperature difference between the water tank and test specimen does not significantly affect the thermal expansion coefficient measurement because the important point is not the actual temperature value but the temperature gradient. For reliability evaluation, a statistical significance review of the strain distribution by measurement method is performed via a T-test comparing with the AASHTO test result (12.423με/°C) and the reliability level for each measurement method remains confidential.

The stone pagoda continued to be damaged by weathering and corrosion over time, and natural disasters such as earthquake are accelerating the destruction of cultural properties. Stone pagoda has discontinuous structure behavior and is very vulnerable to the seismic load acting in lateral direction. It is necessary to analyze various design variables as the contact surface characteristics play an important role in the dynamic behavior of stone pagodas. For this purpose, contact surface characteristics of stone pagoda can be classified according to surface roughness and filler type, and representative model is selected and structural modeling and analysis are performed using the discrete element method. Also, the seismic load according to the repetition period is calculated and the dynamic analysis is performed considering the discontinuous characteristics of the stone pagoda. Finally, the seismic behavior characteristics can be analyzed by the evaluation of stresses, displacements and structural safety.

Indoor Volatile organic compounds (VOCs) are classified as known or possible toxicants and odorants. This study characterized VOC levels in 11 homes in an area in the capital of Seoul by using two different methods of VOCs sampling, which are the active sampling using a thermal sorption tube and the passive sampling using a diffusion sampler. When using the active sampling method, the total target VOC concentration ranged from 41.7 to 420.7 μg/ m3 (mean 230.4 μg/m3; median 221.8 μg/m3) during winter and 21.3 to 1,431.9 μg/m3 (mean 340.1 μg/m3; median 175.4 μg/m3) during summer. When using the passive method, 29.6 to 257.5 μg/m3 (mean 81.8 μg/m3; median 49.4 μg/m3) during winter and 1.2 to 5,131.1 μg/m3 (mean 1,758.8 μg/m3; median 1,375.1 μg/m3) during summer. Forty-nine VOCs were quantified and toluene showed the highest concentration regardless of the season and the sampling method studied. The distribution of VOCs was relatively varied by using the active method. However, it showed a low correlation with indoor environmental factors such as room temperature, humidity and ventilation time. The correlation between indoor environmental factors and VOCs were relatively high in the passive method. In particular, these characteristics were confirmed by principal component analysis.

In this study, we conducted a shake table test to verify the seismic performance of the paneling system with steel truss composed of bolt connections. The control group was set to the traditional paneling system with steel truss connected by spot welding method. Test results showed that the bolted connection type paneling system has excellent deformation capacity without cracking or brittle fracture of the steel truss connection parts compared to the welding type paneling system. Furthermore, in the bolted connection type, slight damage occurred at the time of occurrence of the same story drift angle as compared with the existing method, it is considered that it has excellent seismic performance. In compliance with the performance-based design recommended for the current code (ASCE 41-13) on non-structural components, it is judged that in the case of the bolted connection type paneling system, it can be applied to all risk category structures without restriction. However, in the case of traditional paneling system with spot welding method, it is considered that it can be applied limitedly.

The aim of this study is to investigate the effect of wear resistance with 3D printing of DLP(Digital Light Processing). For this purpose, three wear factor which are wear loss, coefficient of friction and friction force applied to test wear-resistance. Wear test of ball-on-disk has been performed using steel balls to determine the variation of wear characteristics. Finally, the coefficient of wear was calculated by the Archard wear equation with 3D printing of DLP.

목 적: 각막굴절교정 수술안에서 이중경로방식(double-pass technique)으로 측정한 객관적인 시력을 정 시안과 비교하였다. 방 법: 근시각막굴절교정 수술을 받은 68명(135안, 평균: 23.49±2.5세)과 정시안 20명(40안, 평균: 22.50±1.7세)을 대상으로 ETDRS 시력표를 이용하여 대비도가 100%인 고대비시력(high contrast visual acuity: HCVA)과 10%인 저대비시력(low contrast visual acuity: LCVA)을 밝은 조명과 어두운 조명 상태에서 측정하였고, OQAS(Optical Quality Analysis System) 장비를 이용하여 광학적 질과 관련 있는 객관적 시력변수인 OVs(OQAS values)와 VA(visual acuity)을 100%, 20% 및 9%의 대비도에 따라 각각 측정하였다. 결 과: 수술안군과 정시안군 사이에서 ETDRS로 측정한 주관적 시력은 밝은 조명 상태에서는 유의한 차 이가 없었지만, 어두운 조명 상태에서는 고대비시력과 저대비시력 모두 유의한 차이가 있었다(p=0.027, p=0.002). OQAS로 측정한 OVs는 두 그룹 사이에서 통계적으로 유의한 차이가 있었고(p=0.012, p=0.003, p=0.001). 수술안군의 객관적 시력은 대비도가 낮을수록 더 감소하였고, 주관적 시력과 상관성이 있었으며 (p<0.05), 어두운 조명 상태의 저대비시력과 VA9%의 상관성이 가장 높았다(R=-0.403). 결 론: 수술안군에서 OQAS로 측정한 객관적 시력은 정시안군과 비교하여 낮았고, 특히, 낮은 대비도에 서 시력은 정시안군보다 더 낮은 것으로 나타났다.

목 적: 셔터 방식과 편광 방식의 3D TV로 3D 영상을 시청할 때 발생하는 피로도, 디스플레이 품질 및 안경 착용감을 비교하고자 했다. 방 법: 42명의 대상자에게 시력에 맞게 처방된 셔터 방식과 편광 방식의 3D 안경을 착용시키고 40분 길이의 두 편의 3D 영상을 관람시켰다. 영상물을 시청하는 동안 대상자의 눈앞에 놓인 RED 500 고정식 아이트래커를 이용하여 동공 크기와 눈 깜박임을 측정하였고, 시청 전후 피로도 및 시청 후 디스플레이의 품질과 안경 착용감에 관한 설문을 실시하였다. 결 과: 설문조사 결과 3D 영상물을 시청한 후 피로도가 증가한 것으로 나타났으나, 셔터 방식과 편광 방식 사이에 유의한 차이는 없었으며, 3D 안경의 착용감은 편광 방식이 셔터 방식보다 더 편한 것으로 나타났다. 셔터방식과 편광방식의 3D 시청조건을 비교했을 때 셔터방식이 편광방식보다 평균 동공 크기가 더 작았고(3.35±0.65mm vs. 3.60±0.74mm), 눈 깜박임 간격이 더 짧았다(3.36±1.75s vs. 4.50±2.96s). 결 론: 본 연구에서 3D 시청으로 발생하는 주관적인 시각적 피로는 편광 방식이 셔터 방식보다 더 적은 것으로 나타났지만 유의성이 없었고, 3D 시청으로 인해 발생되는 시각적 피로도를 측정할 수 있는 정량화된 방법을 제시한 것으로 생각된다.