A Comparison of Stereoacuity by The Verhoeff Stereoptor and Clinical Stereopsis Tests

HyeongSu KIM,ByeongYeon Moon,DongSik Yu,HyunGug Cho 대한시과학회 2017 대한시과학회지 학술대회 Vol.2017 No.06

Purpose: To examine whether the results of the Verhoeff stereoptor would correlate with those of clinical stereopsis tests used in optometric practice. Methods: This study involved 40 normal young adults, 18 women and 22 men, with ages of 21.82±1.22 years. All participants had visual acuity with better than 0.8 in conditions with or without glasses or contact lenses and they had no strabismus. The stereotests were performed that TNO test and Titmus test were at 40 cm, and Verhoeff stereoptor (a depth of 2.5 mm) and Frisby test (a depth of 6.0 mm) were at depth perception threshold (at closer distances recognizing depth perception). All tests were repeated four times and stereoacuity was expressed by mean seconds of arc. Results: The depth perception threshold were 871.43±243.19 mm in Verhoeff stereoptor and 772.86±439.34 mm in the Frisby test. The depth perception threshold in Verhoeff stereoptor showed a positive correlation with Frisby test (r=0.769, p=0.000). The stereoacuity were 51.30±24.12 seconds of arc in Verhoeff stereoptor, 235.94±292.29 seconds of arc in Frisby test, 100.59±71.10 seconds of arc in TNO Stereotest and 71.90±52.40 seconds of arc in Titmus Stereotest. Conclusions: Verhoeff stereoptor test, examining depth perception has the lowest standard deviation in four different tests and a positive correlation with Frisby stereopsis test.

Aquaponics application research based on biofloc technology aquaculture

Hyeongsu Kim,Ju-Ae Hwang,Donggil Lee,Jeon-Ho Lee 한국수산과학회 양식분과 2021 한국수산과학회 양식분과 학술대회 Vol.2021 No.4

Factors Affecting the Designation of Cerebrovascular Diseases as Work-Related in Administrative Litigation

Hyeongsu Kim,Jaewook Choi,Hwayoung Rim,Sounghoon Chang,Kunsei Le 대한의학회 2008 Journal of Korean medical science Vol.23 No.2

The purpose of this study was to identify factors that could be used as standardized criteria for evaluating occupational diseases in initial assessments or requests for examination. Using 100 administrative litigation cases on the work-relatedness of cerebrovascular diseases (CVDs) by the Seoul Branch of the Korea Labor Welfare Corporation (KLWC) from 1997 to 2002, we estimated the relationship between the investigated variables and designation of the work-relatedness of the CVD. As for the age, the odds ratio of the acceptance rate of a case as work-related in subjects over 60 yr of age was 0.08 (95% CI, 0.01-0.75), which was compared to subjects under 30 yr of age. Regarding working hours, the odds ratio of the acceptance rate of a case as work-related in CVDs in those over 56 hr was 9.50 (95% CI, 1.92-47.10) when compared to those less than 56 hr. As for the benefit type, the odds ratio of the acceptance rate of a case as work-related in medical benefits was 5.74 (95% CI, 1.29-25.54), compared to survivor benefits. As for the criteria for defining situations as work overload, the odds ratio of the acceptance rate of a case as work-related in injured workers was 12.06 (95% CI, 3.12-46.62), compared to that in non-injured workers. Our findings show that the criteria for defining situations of work overload played an important role in assessing the work-relatedness of CVDs in administrative litigation, and it is necessary to make the scientific evidence on judgement of workrelatedness on overwork.

Flame Retardancy and Thermal Properties of PVC/ATH Composites Prepared by a Modular Intermeshing Co-rotating Twin Screw Extruder

( Hyeongsu Lee ),( Se-ho Park ),( Jae-yeul Lee ),( Yuri Park ),( Hobin Jeong ),( Kwang-hwan Jhee ),( Daesuk Bang ) 한국고무학회 2016 엘라스토머 및 콤포지트 Vol.51 No.2

Polyvinyl chloride (PVC) has been used as a general-purpose polymer because of its lower cost, good durability and mechanical properties compared to other materials. However, PVC is vulnerable to heat deformation and generates a toxic gas like hydrogen chloride. Therefore, it is important to delay or prevent the flame retardancy and thermal degradation of the PVC during the processing. It was reported that aluminum trihydroxide (ATH) improved flame retardancy as well as smoke inhibition of the virgin polymer. In this study, PVC composites by addition of ATH were compounded in a modular intermeshing co-rotating twin screw extruder. The PVC composites with different concentrations of ATH (0~5 phr) were analyzed. Flame retardancy of the PVC composite significantly increased depending on the ATH concentration. LOI of the composite also increased with the concentration of ATH. There were no significant differences for the thermal properties of the PVC composites with ATH.

Fish farm monitoring report for outdoor aquaculture of far eastern catfish Silurus asotus in Korea

Hyeongsu Kim,Jongsung Park,Bokki Choi 한국수산과학회 2023 Fisheries and Aquatic Sciences Vol.26 No.11

This study aimed to investigate the growth performance of far eastern catfish (Silurus asotus) on outdoor fish farms to obtain basic data for the domestic eastern catfish aquaculture industry. An outdoor fish farm was directly monitored from June 2018 to October 2019 to determine the farming conditions, growth performance, and water quality. The growth performance in 2017 was analyzed using data from the same fish farm. Three years of monitoring showed that the fish farm required approximately 5–6 months between stocking, harvesting, and selling an S. asotus batch. The growth parameters, namely, the weight gain rate (WGR), specific growth rate (SGR) for culture periods, SGR for feeding periods, and feed coefficient rate (FCR), were 4,664.7%, 1.27%, 2.43%, and 1.25 in 2017; 6,452.0%, 1.52%, 2.79%, and 1.42 in 2018; and 3,270.0%, 1.11%, 2.12%, and 1.38 in 2019, respectively. Moreover, the WGR was two-fold higher in 2018 than 2019, whereas the FCR was more effective in 2019 than 2018, presumably because of the stocking density. No mass mortality was observed during the water quality analysis. The results of this study provide basic data for the development of the catfish industry.

Study on Mechanical Properties of PP/Elastomer Composites for Automobile Bumpers

Hyeongsu Lee,Yuri Park,Rami Lee,Daesuk Bang 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

Effect of Biofloc system on growth and water quality in Korean bullhead (Pseudobagrus fulvidraco)

Hyeongsu Kim,Wongwan Jeong,Jongsung Park,Na Na Kim,Jeong-Ho Lee 한국수산해양기술학회(구 한국어업기술학회) 2018 한국수산해양기술학회 학술발표대회 Vol.2018 No.11

Fabrication of high crystalline SnS and SnS₂ thin films, and their switching device characteristics

Choi, Hyeongsu,Lee, Jeongsu,Shin, Seokyoon,Lee, Juhyun,Lee, Seungjin,Park, Hyunwoo,Kwon, Sejin,Lee, Namgue,Bang, Minwook,Lee, Seung-Beck,Jeon, Hyeongtag IOP Pub 2018 Nanotechnology Vol.29 No.21

<P>Representative tin sulfide compounds, tin monosulfide (SnS) and tin disulfide (SnS<SUB>2</SUB>) are strong candidates for future nanoelectronic devices, based on non-toxicity, low cost, unique structures and optoelectronic properties. However, it is insufficient for synthesizing of tin sulfide thin films using vapor phase deposition method which is capable of fabricating reproducible device and securing high quality films, and their device characteristics. In this study, we obtained highly crystalline SnS thin films by atomic layer deposition and obtained highly crystalline SnS<SUB>2</SUB> thin films by phase transition of the SnS thin films. The SnS thin film was transformed into SnS<SUB>2</SUB> thin film by annealing at 450 °C for 1 h in H<SUB>2</SUB>S atmosphere. This phase transition was confirmed by x-ray diffractometer and x-ray photoelectron spectroscopy, and we studied the cause of the phase transition. We then compared the film characteristics of these two tin sulfide thin films and their switching device characteristics. SnS and SnS<SUB>2</SUB> thin films had optical bandgaps of 1.35 and 2.70 eV, and absorption coefficients of about 10<SUP>5</SUP> and 10<SUP>4</SUP> cm<SUP>−1</SUP> in the visible region, respectively. In addition, SnS and SnS<SUB>2</SUB> thin films exhibited p-type and n-type semiconductor characteristics. In the images of high resolution-transmission electron microscopy, SnS and SnS<SUB>2</SUB> directly showed a highly crystalline orthorhombic and hexagonal layered structure. The field effect transistors of SnS and SnS<SUB>2</SUB> thin films exhibited on–off drain current ratios of 8.8 and 2.1 × 10<SUP>3</SUP> and mobilities of 0.21 and 0.014 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, respectively. This difference in switching device characteristics mainly depends on the carrier concentration because it contributes to off-state conductance and mobility. The major carrier concentrations of the SnS and SnS<SUB>2</SUB> thin films were 6.0?×?10<SUP>16</SUP> and 8.7?×?10<SUP>13</SUP> cm<SUP>−3</SUP>, respectively, in this experiment.</P>

Degradation of trichloroethylene by Fenton reaction in pyrite suspension

Che, Hyeongsu,Bae, Sungjun,Lee, Woojin Elsevier 2011 Journal of hazardous materials Vol.185 No.2

<P><B>Abstract</B></P><P>Degradation of trichloroethylene (TCE) by Fenton reaction in pyrite suspension was investigated in a closed batch system under various experimental conditions. TCE was oxidatively degraded by OH in the pyrite Fenton system and its degradation kinetics was significantly enhanced by the catalysis of pyrite to form OH by decomposing H<SUB>2</SUB>O<SUB>2</SUB>. In contrast to an ordinary classic Fenton reaction showing a second-order kinetics, the oxidative degradation of TCE by the pyrite Fenton reaction was properly fitted by a pseudo-first-order rate law. Degradation kinetics of TCE in the pyrite Fenton reaction was significantly influenced by concentrations of pyrite and H<SUB>2</SUB>O<SUB>2</SUB> and initial suspension pH. Kinetic rate constant of TCE increased proportionally (0.0030±0.0001–0.1910±0.0078min<SUP>−1</SUP>) as the pyrite concentration increased 0.21–12.82g/L. TCE removal was more than 97%, once H<SUB>2</SUB>O<SUB>2</SUB> addition exceeded 125mM at initial pH 3. The kinetic rate constant also increased (0.0160±0.005–0.0516±0.0029min<SUP>−1</SUP>) as H<SUB>2</SUB>O<SUB>2</SUB> concentration increased 21–251mM, however its increase showed a saturation pattern. The kinetic rate constant decreased (0.0516±0.0029–0.0079±0.0021min<SUP>−1</SUP>) as initial suspension pH increased 3–11. We did not observe any significant effect of TCE concentration on the degradation kinetics of TCE in the pyrite Fenton reaction as TCE concentration increased.</P>

추령천에 서식하는 가시납지리, Acheilognathus chankaensis (Pisces: Acheilognathinae)의 개체군 생태

김형수 ( Hyeongsu Kim ),김수환 ( Suhwan Kim ) 한국환경생태학회 2021 한국환경생태학회지 Vol.35 No.2

본 연구는 전라북도 순창군 복흥면 추령천 일대에서 2006년 2월부터 2007년 5월까지 가시납지리의 개체군 생태조사를 실시하였다. 가시납지리는 물의 흐름이 느리고 하상이 주로 모래, 뻘, 잔자갈의 비율이 높은 수역에서 서식하였다. 체장빈도분 포법으로 연령을 추정한 결과, 체장 30~46㎜ 군은 만 1년생, 47~58㎜ 군은 만 2년생, 59~68㎜ 군은 만 3년생, 69㎜이상 군은 만 4년생 이상으로 추정되었다. 생식소성숙도지수(GSI)는 3월(암: 12.9%, 수: 5.0%)에 가장 높았고, 산란관길이/체장(Ovipositor length/Standard length)의 비율(%)은 4월(46.3%)에 가장 높았다. 성숙란인 1.6㎜ 이상 크기의 난경이 차지하는 비율은 5월(13.2%)에 가장 높게 나타났다. 산란기 특성을 종합적으로 분석한 결과 산란기는 3월부터 6월까지로 추정되었고 (수온 11.5~22.5℃) 조사기간 동안 성비는 1:1.13(♀:♂)이었다. 포란수는 318±174.5 (50~583)개, 성숙란수는 220±139.2 (50~406)개, 성숙난의 크기는 장경 2.04±0.110㎜, 단경 1.55±0.100㎜으로 나타났다. 가시납지리의 주요 먹이생물은 규조류(Bacilariophyceae)의 Fragilaria, Synedra, Navicular, Cymbella 등과 녹조류(Chlorophyceae)의 Cosmarium 같은 식물성플랑크톤이 주로 관찰되었다. This study surveyed the population ecology of Acheilognathus chankaensis (Pisces: Acheilognathinae) in the vicinity of the Churyeongcheon (Stream) and Seomjingang (River) in Jeonbuk, Korea, from February 2006 to May 2007. The survey found the habits mainly in the slow-flowing waters having sand, mud, and gravel bottoms. Age groups estimated by the standard length-frequency distribution of the population indicated that the one-year-olds were 30-46 ㎜ long, the two-year-olds were 47-58 ㎜ long, the three-year-olds were 59-68 ㎜ long, and the four-year-olds were longer than 69 ㎜. The gonadosomatic index (GSI) and the ratio of ovipositor length/standard length were the highest in March (♀: 12.9%, ♂: 5.0%) and in April (46.3%), respectively. The ratio of mature egg diameters that were 1.6 ㎜ was highest in May (13.2%). The comprehensive analysis of spawning characteristics showed that the spawning season was from March to June with water temperatures in 11.5-22.5℃, and the sex ratio of female:male was 1:1.13. The fecundity in the ovaries and the number of mature eggs were 318±174.5 (50~583) and 220±139.2 (50~406), respectively. The size of the mature eggs was 2.04±0.110 ㎜ on the long axis and 1.55±0.100 ㎜ on the short axis for the study period. Gut contents of A. chankaensis were mainly phytoplankton such as the genera Fragilaria, Synedra, Navicular, Cymbella (Bacillariophyceae), and Cosmarium (Chlorophyceae).