• 한국재료학회지
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• 제4권3호
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• pp.253-258
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• 1994

S2-유리 섬유/폴리에스터 브레이드 복합재료에서 원공의 크기 및 원공간 거리 변화가 인장성질, 핀하중 인장성질, 굽힘성질에 미치는 영향을 연구하였다. 원공의 크기에 따른 복합재료의 인장강도의 저하는 Whitney와 Nuismer에 의해 제시된 이론값과 대체로 일치함을 보여주었으며 이때의 특성길이($d_o$)는 브레이드 복합재료는 약 1.6mm, 직물 적층 복합재료는 약 1.8mm가 되었다. 브레이드 복합재료의 원공간 거리 변화에 따른 인장강도의 변화는 두 원공 중심 사이의 거리가 원공 지름의 4배 이상이면 원공간 상호작용이 없었다. 원공의 중심과 측면간 거리에 따른 인장강도의 변화는 원공의중심과 측면간 거리가 원공 지름의 3배 이상일 때 상호작용이 없었다. 핀하중 인장실험에서 브레이드 복합재료와 직물 적층 복합재료 모두 핀의 지름이 증가함에 따라 Bearing Stength는 감소하였다.

• 대한치과보철학회지
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• 제34권4호
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• pp.665-674
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• 1996

This study was designed to evaluate the effect of processing method and surface design on the transverse strength of repaired denture base resin. Three heat-cured denture base resins(Vertex, Lucitone, Lang), one cold-cured resin(Lang), and one light-cured resin(Dentacolor gingiva material) were used for repair purpose. The specimens for 3-point flexure test were fabricated by five processing methods such as self-curing, pressure pot, boiling water, processing, and light curing. Finally to evaluate the effect of surface designs for repaired resin, three surface designs(butt, bevel, inverse bevel) were tested. Within the limit of this study, following conclusions were drawn. 1. Lucitone denture base material showed highest flexural strength of $131.37{\pm}2.15MPa$, and there were significant differences in stength between Lucitone and other resins. 2. Between two different self curing methods, self curing repair resin, Lang, cured by pressure pot method showed highest flexural strength, $58.49{\pm}4.89MPa$. 3. Among the heat cured repair resins, maximum transverse strength value of $88.69{\pm}16.60MPa$ was recorded in Lucitone group cured by processing method. 4. Inverse bevel joint design showed significantly higher bond strength than butt joint group, Maximum bond strength was $59.36{\pm}1.33MPa$ in inverse bevel joint design group.

• 대한화학회지
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• 제38권8호
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• pp.590-597
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• 1994

유기 리간드(2,2,6,6-테트라메틸-3,5-헵탄내디온)을 란탄나이드 3가$(Pr^{3+}, Eu^{3+}, Gd^{3+} 그리고 Yb^{3+})$와의 착물들에 대한 거동을 UV-Vis 분광학적, 자기적, 그리고 전기화학적 방법에 의해 조사하였다. 2 또는 3개의 에너지 흡수띠가 이들 착물들의 스펙트라에 의해 관찰되었다. 결정장 갈라짐 에너지 크기와 스핀 또는 3개의 에너지 흡수띠가 이들 착물들의 스펙트라에 의해 관찰되었다. 결정장 갈라짐 에너지 크기와 스핀 짝지움 에너지 그리고 결합세기는 착물들의 스펙트라로부터 얻어졌다. 이들은 편재화이고, 낮은 스핀(또는 높은 스핀) 상태이며 그리고 강한 결합세기임을 알았다. 착물들의 거동은 비수용매속에서 순환전압전류법에 의해 관찰하였다. 이들 환원피크는 전자전이에 의한 2 또는 3단계의 비가역성이었다.

• 한국농공학회지
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• 제33권2호
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• pp.61-72
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• 1991

This study was carried out to research the strength drop of concrete in dry environment. The mixing ratio of cement-fine aggregate was 1: 1, 1 : 2, 1: 3 and 1 : 4. The curing was compared standard curing with dry curing immediately after casting. It is analysis of strength change by water-proof mixing. The curing age of cement mortar was 3days, 7days, l4days and 28days. The result obtained from this study are summarized as follows. 1. The compressive and bending strength change by increasing the curing age, dry curing mortar the increasing rate of strength was decreased than standard curing mortar. 2. The compressive and bending strength change in early curing, strength difference between standard curing mortar and dry curing motar was gradually closed by increasing the W/C. 3. The dry curing mortar was decreased than standard curing mortar in decreasing rate of compressive and bending strength by increasing the W/C. 4. The compressive strength of water-proof mortar in early curing, liquid water-proof mortar was shown high strength in dry curing than standard curing. The powder and liquid water-proof mortar have a small effect in dry environment. The liquid water-proof mortar was high strength without relation change of curing age in dry environment than standard curing. 5. The compressive strength of liquid water-proof mortar in poverty mix, dry curing was shown high strength than standard curing. 6. The bending strength was increased than compressive strength by decreasing the volume of cement in early curing. The increasing rate of bending strength was decreased to compressive stength by increasing the curing age.

• 조명전기설비학회논문지
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• 제15권4호
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• pp.43-50
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• 2001

본 논문은 구대구전극 사이에 고체절연체와 화염을 배치하여 방전시 절연체표면에서 발생되는 연면방전광과 화염의 변화를 CCD(Charged Coupled Device) 카메라로 관측하였으며, 방전시 발생되는 방사전자파는 스펙트럼 분석기와 바이코니칼 안테나를 이용하여 측정하였다. 인가전압 증가에 따른 고체절연체 표면에서 발생되는 연면 방전광은 커졌으며, 화염의 크기는 작아지는 것을 확인하였다. 또한 절연체표면 오염시와 화염시에는 전압강하에 의한 전압왜곡현상이 나타났다. 방사전자파의 전계세기는 절연체표면 무오염시에는 오염시보다 10∼17(dBuV/m), 절연체표면 오염시와 화염시에는 5∼9[dBuV/m]정도 높게 나타났다.

• 식물조직배양학회지
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• 제27권3호
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• pp.191-195
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• 2000

사과나무 교배잡종 (P.16 $\times$ M. prunifolia)의 자엽과 배축 조직을 배양하여 신초의 재분화에 미치는 2,4-D, NAA 키네틴, BA, thidiazuron의 처리효과를 조사하였다. 자엽조직은 1.0 mg/L＋ NAA +2.0 mg/L BA 처리구에서, 배축조직은 0.5 mg/L NAA+0.5mg/L BA처리구에서 가장 많은 수의 신초가 분화하였으며, BA 무첨가구에서는 신초의 재분화가 전혀 이루어지지 않았다. 자엽조직보다는 배축조직을 배양하는 것이 더 효과적이었으며 특히, 배축의 상위부분을 치상하였을때 신초 재분화가 더 양호하였다. 재분화된 신초를 1/2 MS에 1.0mg/L NAA를 첨가한 발근배지에 계대배양한 결과 발근이 양호하였으며 정상적인 식물체로 생장하였다.

• 한국농공학회지
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• 제17권4호
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• pp.3931-3942
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• 1975

This study was conducted to investigate the strength of soil cement for varied curing temperatures (0,10,20,30,40,50,60$^{\circ}C$) and cement content (3,6,9,12%) in four cement-stabilized soils (KY: sand, MH: sand, SS: sandy loam, JJ:loam). The experimental results obtained from unconfined compressive strength tests were as follows: 1. According to increase of curing temperature as 30,40,50, and 60$^{\circ}C$, the unconfiened compressive strength of soil cement increased, the rate of increase in the early curing period was large, and around 120 hours was suifficient curing time to complete hardening. 2. The strength at 10$^{\circ}C$ decreased to the rate of 30 to 40 percent than that of 20$^{\circ}C$ while the strength at 0$^{\circ}C$ was very small, strength of soil cement increased in cold weather unless that the temperature was below 0$^{\circ}C$ 3. The average maximum temperature, about 30$^{\circ}C$ during July and August in Korea may be recommended for a optimum construction period to increase the strength of soil cement. 4. Accelerated curing time that strength was equivalent to 28-Day norma1 curing decreased in accordance with the increase of curing temperature, and also accelerated curing decreased the effect of cement content. Accelerated curing that strength was equivalent to 28-day normal curing for soil cement of cement content 9% and temperature 60$^{\circ}C$ was 45 hours; KY, 50 hours: MH, 40 hours; SS, 34 hours; JJ. 5. According to the increase of the percent passing of No. 200 sieve, accelerated curing times became shorter to become the required stength. 6. Relation between accelerated curing times and normal curing days was showeda linear of which slope decreased in accordance with the increase of curing temperature, it may be expressed as follows: (1). 30$^{\circ}C$ t=3.6d+6(r=0.97) (2). 40$^{\circ}C$ t=3.2d-5.1(r=0.95) (3). 50$^{\circ}C$ t=2.1d-4.0(r=0.93) (4). 60$^{\circ}C$ t=1.4d+4.0(r=0.90) in which t=accelerate curing time. d=normal curing day. 7. Accelerated curing time that the strength was equivalent to 35kg/$\textrm{cm}^2$ which was the strength of cement brick was 96 hours at temperature 30$^{\circ}C$ to SS 9%, and 120 hours at temperature 50$^{\circ}C$ to JJ 9%, Consequently, a economic soil cement brick may be made in future.

• 한국안전학회지
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• 제31권4호
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• pp.111-119
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• 2016

This study aimed to analyze postures that were frequently conducted in manufacturing industry. To find grip strength and muscle activities of each posture, Maximum Voluntary Contraction (MVC) and ElectroMyoGraphy (EMG) were measured. Based on the results of this study, the most appropriate posture could be suggested and used as a basic information for preventing musculoskeletal disorders. Most work-related musculoskeletal disorders have been occurred in the fields of manufacturing industry. According to previous studies, it was reported that the rate of musculoskeletal diseases of upper extremity was higher than that of other body parts. Accordingly, there were many studies about discomfort and grip strength of upper extremity. However, these studies dealt with single selection of wrist, elbow and shoulder. So, it was insufficient for comprehensive studies about upper extremity. And in order to improve the work posture, the physiological changes being generated by the combination of wrist, elbow and shoulder postures should be observed and analyzed. In order to conduct this study, thirty university students who had no records of MSDs involved were recruited. Independent variables were postures of wrist(pronation, neutral, supination), postures of elbow(flexion $45^{\circ}$, $90^{\circ}$) and postures of shoulder(flexion $0^{\circ}$, $90^{\circ}$). And dependent variables were MVC values and EMG values. Jamar dynamometer and TeleMyo 2400T G2 was used to measure MVC and EMG. MVC and EMG for 12 postures were measured for three second and for three times. Experiment was performed randomly. A 10 minutes rest period was provided after each t. To measure muscle load, the EMG signals of eight muscles (Biceps, Medial triceps, Lateral triceps, Brachioradialis, Extensor carpi ulnaris, Extensor carpi radialis, Flexor carpi ulnaris and Flexor carpi radialis) were evaluated. MVC values and EMG values were analyzed using Minitab ver. 14. The results showed that MVC value was the highest at shoulder $0^{\circ}$, elbow $45^{\circ}$ and wrist supination. In case of wrist postures, MVC of supination is the highest. In case of elbow and shoulder postures, MVC of flexion $45^{\circ}$ and $0^{\circ}$ was the highest. It was found that there were interaction between wrist and elbow posture under shoulder flexion and between shoulder and wrist under elbow flexion $45^{\circ}$. In case of the angle of shoulder $0^{\circ}$, elbow $45^{\circ}$ and wrist supination, the EMG values of four muscles(Medial Triceps, Extensor carpi ulnaris, Extensor carpi radialis, Flexor carpi ulnaris) were the highest. Based on this study, it is worth to note that the combination postures of upper extremity have a large impact on the MVC and EMG. The optimal condition upper extremity was shoulder flexion $0^{\circ}$, elbow flexion $45^{\circ}$ and wrist supination for preventing work-related musculoskeletal disease.

• 생물환경조절학회지
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• 제12권4호
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• pp.235-239
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• 2003

본 실험은 수경재배시 마죠람과 오레가노의 알맞은 배양액 농도를 구명하기 위하여 실시했다. 배양액은 유럽채소연구센터 허브액을 사용했다. 처리농도는 0.5, 1.0, 2.0, 3.0배액 등 4수준이었고 재배기간은 40일이었다. 마죠람은 지상부 생육, 지하부 생육, 비타민 C,총 정유생산량은 0.5배액에서 가정 조았다. 그러나 무기물함량은 20.배액에서, 정유함량은 3배액에서 좋았으며 엽록소 함량은 고농도에서 감소하였다. 오래가노의 생육 0.5배야ㅐㄱ에서 조았으며, 3.0배액에서는 고사하였다. 엽록소 함량은 2.0배액에서 낮았으나 비타민 C는 이온농도에 영향을 받지 않았다. 무기물과 정유함량은 1.0배액에서 높았으나, 정유생산량은 0.5배액에서 높았다. 이사의 결과로 볼 때 마죠람과 오레가노 수경재배시 적절한 배양액 농도는 허브 배야액 0.5배인 것으로 생각된다.

• 대한물리치료과학회지
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• 제24권1호
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• pp.1-13
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• 2017

Purpose: The objective of this study was compare the effect of core muscle strengthening between core exercise on stable surface and core exercise on unstable surface. Methods: Thirty-nine adults participated in this study and were randomly allocated to three groups. The stable surface exercise group and unstable surface exercise groups practiced core muscle training for $3{\times}30minute$ sessions over a 4-week period. The control group did not received therapeutic intervention except pre and post test. The following clinical tools were used to assess core muscle strength and balance: Side Plank Test, Trunk Flexion Test, Balance Error Scoring Test, Core Muscle Stength & Stability Test. Results: The stable surface exercise group showed significant improvement in trunk muscle strength of anterolateral part as revealed by the Side Plank Test and Trunk flexion Test(p<.05). The unstable surface exercise group showed significant improvement in trunk muscle strength of anterolateral part and balance ability as revealed by the Balance Error Scoring Test and Core Muscle Strength & Stability Test(p<.05). Conclusion: The results of this study, both core exercise on stable surface and core exercise on unstable surface induced core muscle strengthening and balance ability. Expecially core exercise on unstable surface more effective to core muscle strengthening and balance ability.