• Journal of the Korean Society for Railway
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• v.15 no.3
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• pp.237-243
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• 2012

In this paper, a magnetic analysis of SRM(Switched Reluctance Motor) using 3d finite element method considering end-coil effect is presented. SRM models with different stator pole shapes are taken into consideration for the analysis of magnetic characteristics. It is observed that a stator pole shape model having a pole shoe depth is the most suitable one for railway traction application because it gives an improved inductance and torque characteristic. For a speed control of SRM, the PI and sliding mode controllers are applied to designed SRM with magnetic characteristic data obtained from the magnetic analysis. The simulations are carried out using Matlab-Simulink and the control performance is analyzed. By employing the sliding mode controller, the transient response as well as the steady-state error are much improved under a load variation of railway resistance under operation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.5
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• pp.28-33
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• 2022

A pipe is a hollow, long-form part that is primarily used to transport fluids, such as liquids or gases. Pipes are used in a range of applications in different fields from mechanical purposes to architecture and electrical uses. Despite the significance owing to various usability of pipes, few studies have been conducted using the physical property test method. The tensile test is widely used as a method to check the physical properties of the pipe. The existing pipe tension test contains the possibility to cause errors, which are fractures outside the gauge distance and cross-sectional deformation of the pipe. In this study, a novel pipe tension test method using a jig is presented and pipes with various materials are tested. It is expected that the proposed method can reduce errors that occur in conventional pipes and also obtain more accurate values to enable more efficient testing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.160-164
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• 1995

정보통신 시스템의 고속/고밀도화 요구에 따라 개발되고 있는 ATM(Asynchronous Transfer Mode) 교환기 시스템은 팬을 이용한 강제대류냉각 방식의 채택과 시스템이 설치되는 장소에 따른 여러 환경조건에 의한 진동 문제가 발생될 수 있다. 시스템의 진동으로 인한 피해중 커넥터 접촉부에서 전기적 특성의 변화는 고속으로 전송되는 신호의 왜곡을 유발시킬 수 있어 시스템 개발시 이에 대한 충분한 연구 및 시험이 요구되고 있다. 진동환경에서 커넥터 접촉부는 접촉면의 상대운동으로 인한 접촉저항의 증가와 순간적인 신호전달 중단을 가져오게 되며, 특히 PCB/Connector Assembly에서 커넥터 접촉부는 PCB(Printed Circuit Board)의 장착 조건 및 동적 거동에 따라 전기적 특성이 변할 수 있다. 시스템에서 커넥터의 동적 거동을 이해하기 위해서는 PCB를 포함하는 시스템내 여러 요소의 동적 특성 이해와 복잡한 해석과정이 요구되며, 시스템 개발자는 진동 환경에서 이것의 시험 결과에 따라 커넥터의 사용을 결정해야 할 것이다. 커넥터의 전기적 특성 시험법은 IEC, EIA드 여러 국제 규격에 제시되어 있으며, 본 연구의 대상이 된 ATM교환기 시스템에서 PCB/Connector Assembly의 진동환경에서 접촉저항 측정과 관련된 접촉저항 임계치 및 측정법은 IEEE 규격 및 Bellcore 규격에 규정되어 있다. Bellcore에는 주어진 진동시험주기 전후에 IEC 규격의 LLCR(Low Level Contact Resistance) 측정회로를 이용한 측정법이 규정되어 있고, 냉각팬 및 주위 환경진동이 가해지는 동안의 영향에 대한 시험법은 규정되어 있지 않다. 본 연구에서는 한국통신의 전자장비 운용환경시험 조건의 진동에서 ATM 교환기 시스템에 사용되는 PCB/Connector Assembly 커넥터 접촉부의 접촉저항 변화와 PCB 진동에 의한 영향을 시험하였다.proach)등이 제시되었고 평면파 영역에 한하여 해서되어져 왔다. 본 논문에서는 분할 접근 방법(Segmentation Approach)을 이용하여 다공 요소로 이루어진 소음기를 해석하는데 적용하였다.로 성능 및 안정도에 영향을 미치므로 주의 깊게 선정해야 한다. 방법의 실질적인 적용에는 어려움이 있다. 본 연구에서는 기존의 방법들의 단점을 극복할 수 있는 새로운 회귀적 모우드 변수 규명 방법을 개발하였다. 이는 Fassois와 Lee가 ARMAX모델의 계수를 효율적으로 추정하기 위하여 개발한 뱉치방법인 Suboptimum Maximum Likelihood 방법[5]를 기초로 하여 개발하였다. 개발된 방법의 장점은 응답 신호에 유색잡음이 존재하여도 모우드 변수들을 항상 정확하게 구할 수 있으며, 또한 알고리즘의 안정성이 보장된 것이다.. 여기서는 실험실 수준의 평 판모델을 제작하고 실제 현장에서 이루어질 수 있는 진동제어 구조물에 대 한 동적실험 및 FRS를 수행하는 과정과 동일하게 따름으로써 실제 발생할 수 있는 오차나 error를 실험실내의 차원에서 파악하여 진동원을 있는 구조 물에 대한 진동제어기술을 보유하고자 한다. 이용한 해마의 부피측정은 해마경화증 환자의 진단에 있어 육안적인 MR 진단이 어려운 제한된 경우에만 실제적 도움을 줄 수 있는 보조적인 방법으로 생각된다.ofile whereas relaxivity at high field is not affected by τS. On the other hand, the change in τV does not affect low field profile but strongly in fluences on both inflection fie이 and the maximum relaxivity value. The results shows a fluences on both inflection field and the maximum relaxivity v

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.1
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• pp.37-42
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• 1984

This paper deals with the characterics of the stability of uncontinuous plate structures with cracks. The relation between the J-intergal of the cracks existing in the stress-concentrated regions and local strain are investigated experimentally and theoretically. The BEM(boundary element method)analysis and test results lead to the follow conclusions: 1. A non-dimensional J was computed in a plate stress and strain condition for several kind of loads and crack types. The J design curves are defined as follows: J sub(E)/$\sigma$ sub(y) super(2) a=3.345(e/e sub(y) ) super(2) at e/e sub(y)$\leq$1 J sub(E)/$\sigma$ sub(y) super(2) a=3.345(e/e sub(y) ) at e/e sub(y)$\geq$1 2. Use of this curve provides a good estimation for the uncontinuous plate structures with cracks existing in the stress and strain concentrated region. 3. The stability of the characteristics is mainly depenent upon not the length of cracks but the type of the cracks.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.25 no.2
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• pp.399-408
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• 1995

The purpose of this study was to obtain information on the clinical and radiographic features of the dentigerous cysts in the jaws. For this study, the authors examined and analysed the clinical records and radiographs of 233 patients who had lesions of dentigerous cyst diagnosed by clinical and radiographic or histopathological examinations. And the obtained results were as follows: 1. Dentigerous cysts occurred the most frequently in the 2nd decade(38.2％) and occurred more frequently in males(67.4％) than in females(32.6％). 2. The most common clinical symptom was swelling of the jaw(33.9％), and the lesions were treated by the method of surgical removal. 3. The type of lesions was mainly observed as central type(72.5％), and size of the lesion was most frequently observed 2 - 2.9cm in the widest length. 4. The lesions were most frequently observed well-defined outline with hyperostotic border(49.8％), and smooth margin(73.4％), and homogeneous lesional radiolucency(79.4％). 5. Cortical thinning and expansion of the lesions(82.0％) were observed, and their direction were most frequently observed toward buccal side(64.0％). 6. The effect on the causative tooth were observed as tooth displacement(41.2％) and delayed root development(l9.3％), and the distance between cemento-enamel junction and lesional wall attachment of the causative tooth was mainly observed as below 2mm(79.6％). 7. The effect on the adjacent tooth were observed as loss of lamina dura(66.8％), root resorption(33.9％), and tooth displacement(31.5％). 8. The effects on the adjacent anatomic structures were observed as displacement of the mandibular canal(46.5％) and maxillary sinus or nasal cavity(72.2％).

• Journal of Chest Surgery
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• v.29 no.8
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• pp.889-896
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• 1996

Aggressive revascularization of the ischemic lower extremities in atherosclerotic occlusive diseases or acute embolic arterial occusion due to cardiac valvular disease by thromboembolectomy or an arterial by- pass operation has been advocated by some authors. To evaluate clinical pattern and operative outcome of the ischemic lower extremity, surgical experience in 101 patients who were admitted to Dong-A Univer- sity Hospital between March 1990 and August 1995 was analyzed. The patients were 92 males and 9 females ranging fro 25 to 87 years of age. The underlying causes of arterial occlusive disease were atherosclerotic obliterances in 54 case, Buerger's disease in 20 cases, thromboembolism in 24 cases, vascular trauma in 3 cases and pseudoaneurysm in 3 cases. - The major arterial occlusive sites of atherosclerotic obliterance were femoral artery in 30 cases, iliac artery in 23 cases, popliteal artery in 10 cases, distal aorta in 6 cases and the major arterial occlusive sites of Buerger's disease were posterior tibial artery in 14 cases, anterior tibial artery in 8 cases, popliteal artery in 5 cases. The operative procedures of arterial occlusive disease were bypass graft operation in 61 cases, thromboembolectomy in 21 cases, sympathectomy in 20 cases. Arterial bypass operations with autogenous or artificial vascular prosthesis were done in 61 cases which Included femoro-popliteal bypass in 21 cases, femoro-femoral bypass in 15 cases, axillo-bifemoral bypass in 7 cases, aorto-bifemoral with inverted Y-gr ft In 3 cases, femoro-profundafemoral bypass in 3 cases, popliteo-tibial bypass in 2 cases, aorto-iliad bypass in 1 case Over all postoperative patency rates were 83.6 oyo at 1 year, 75.5% at 3 years and limb salvage rate was 86.8 oyo . Six patients died in the hospital following vascular surgery for ischemic lower extremities, although the causes of death were not directly related to the vascular reconstructive operative proccedures. The leading causes of death were in the order of multiple organ failure, acute renal failure, and sepsis.

• Journal of Nutrition and Health
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• v.41 no.1
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• pp.31-40
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• 2008

This study was aimed at evaluating the effect of red-yeast-rice supplementation on cholesterol-lowering and glucose control in subjects with impaired fasting glucose (IFT) or impaired glucose tolerance (IGT). We conducted a doubleblind, placebo-controlled study with 3 groups; placebo, low dose group (red yeast rice 210.0mg/capsule, 2.52g/day) and high dose group (red yeast rice 420.0mg/capsule, 5.04g/day), which were randomly assigned to subjects with impaired fasting glucose or impaired glucose tolerance. We measured fasting serum concentrations of total-, LDL-, HDL-cholesterol, triglyceride, glucose, insulin, free fatty acid (FFA) and 2 h oral glucose tolerence test (OGTT) before and after the supplementation. Both low dose and high dose groups had significant decrease in LDL cholesterol and atherogenic index (AI) compared with placebo group (p<0.05). Additionally, total and HDL cholesterol improved significantly in high dose group compared with placebo group (p<0.05). Fasting serum glucose decreased in test groups and increased in placebo group after intervention. However, it was not significant differences. In subjects which fasting blood glucose is more than 110mg/dL, fasting glucose had a tendency to decrease in high dose group (p<0.1) and Hemoglobin A1c (HbA1c) had significant decrease in low dose group (p<0.05), while insulin and HOMA-IR had a tendency to increase in placebo group after intervention. Mean changes of glucose related parameters (fasting glucose, insulin, HOMA-IR) compared with placebo group did not show significant differences. In conclusion, subjects with impaired fasting glucose or impaired glucose tolerance were significantly improved in serum lipid profile by red yeast rice supplementation without serious side effects. These are more effective in the case of a high dose. The effects of red yeast rice supplementation on glucose control were insignificant.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.18
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• pp.54-87
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• 1975

The effects of various weather factors on yield components of rice, year variation of yield components within regions, and regional differences of yield components within year were investigated at three Crop Experiment Stations O.R.D., Suweon, Iri, Milyang, and at nine provincial Offices of Rural Development for eight years from 1966 to 1973 for the purpose of providing information required in improving cultural practices and predicting the yield level of rice. The experimental results analyzed by standard partial regression analysis are summarized as follows: 1. When rice was grown in ordinary seasonal culture the number of panicles greatly affected rice yield compared to other yield components. However, when rice was seeded in ordinary season and transplanted late, and transplanted in ordinary season in the northern area the ratio of ripening was closely related to the rice yield. 2. The number of panicles showed the greatest year variation when the Jinheung variety was grown in the northern area. The ripening ratio or 1, 000 grain weight also greatly varied due to years. However, the number of spikelets per unit area showed the greatest effects on yield of the Tongil variety. 2. Regional variation of yield components was classified into five groups; 1) Vegetation dependable type (V), 2) Partial vegetation dependable type (P), 3) Medium type (M), 4) Partial ripening dependable type (P.R), and 5) Ripening dependable type (R). In general, the number of kernel of rice in the southern area showed the greatest partial regression coefficient among yield components. However, in the mid-northern part of country the ripening ratio was one of the component!; affecting rice yield most. 4. A multivariate equation was obtained for both normal planting and late planting by log-transforming from the multiplication of each component of four yield components to additive fashion. It revealed that a more accurate yield could be estimated from the above equation in both cases of ordinary seasonal culture and late transplanting. 5. A highly positive correlation coefficient was obtained between the number of tillers from 20 days after transplanting and the number of panicles at each(tillering) stage 20 days after transplanting in normal planting and late planting methods. 6. A close relationship was found between the number of panicles and weather factors 21 to 30 days, after transplanting. 7. The average temperature 31 to 40 days after transplanting was greatly responsible for the maximum number of tillers while the number of duration of sunshine hours per day 11 to 30 days after transplantation was responsible for that character. The effect of water temperature was negligible. 8. No reasonable prediction for number of panicles was calculated from using either number of tillers or climatic factors. The number of panicles could early be estimated formulating a multiple equation using number of tillers 20 days after transplantation and maximum temperature, temperature range and duration of sunshine for the period of 20 days from 20 to 40 days after transplantation. 9. The effects of maximum temperature and day length 25 to 34 days before heading, on kernel number per panicle, were great in the mid-northern area. However, the minimum temperature and day length greatly affected the kernel number per panicle in the southern area. The maximum temperature had a negative relationship with the kernel number per panicle in the southern area. 10. The maximum temperature was highly responsible for an increased ripening ratio. On the other hand, the minimum temperature at pre-heading and early ripening stages showed an adverse effect on ripening ratio. 11. The 1, 000 grain weight was greatly affected by the maximum temperature during pre- or mid-ripening stage and was negatively associated with the minimum temperature over the entire ripening period.

• International Journal of Highway Engineering
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• v.13 no.3
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• pp.75-82
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• 2011

There is the uncertain period of the construction in case of the products meeting the quality standard of KS M 6080, the quality is degraded because of the abrasive loss of the paint caused by vehicle tires as the traffic amount increases and of the loss and detachment of the glass beads providing the retroreflective function. The abrupt degradation of visibility causes the high frequency of traffic accidents at night and increases the traffic accident rate. Additional supplementary construction induces the direct material and construction costs. As the more cost induction effect than the direct cost, the traffic jam caused by the additional construction increases the indirect social costs such as time cost and vehicle cost. Hence, the study is concerned with performing the abrasion resistance test based on the EN 1436 standard to check and improve the quality of various road marking materials resulting in improving the durability of road marking materials. However, even though the difference in the durability lifetime of resins(binders) is bibliographically or theoretically clear, there was no difference in the durability lifetime (retroreflectivity aspect) of the road marking paint using these binders. The reason is that the bonding of beads was very insufficient or that the cross density caused by crack or freshness was low. Moreover, the measured wet retroreflectivity was distributed as the Rw3 or higher class in average on the basis of EN 1436 but was very insufficient on the basis of the minimum wet threshold retroreflectivity with 100mcd/($m^2{\cdot}lx$) managed overseas.

• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.586-592
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• 2017

In this study, acrylic resins with solids content of 75% were prepared by addition polymerization of n-butyl acrylate (BA), methyl methacrylate (MMA), 2-hydroxypropyl methacrylate (HPMA) and acetoacetoxyethyl methacrylate (AAEM) monomers. At this time, the glass transition temperature ($T_g$) of the acrylic resin was changed to 20, 30 and $40^{\circ}C$, and the hydroxyl value (OH value) was changed to 60, 90 and 120. As a result, the viscosity of acrylic resin increased with increasing $T_g$ and hydroxyl (OH) value. The synthesized acrylic resin was designed to have a high cross-link density to maintain high elasticity and high durability. The crosslinked acrylic resin was used to prepare an acrylic urethane clear coating by curing reaction with a block isocyanate (Desmodur BL-3175). The physical properties of the clear paints were analyzed by measuring viscosity, adhesion, pencil hardness and $60^{\circ}$ specular gloss. Acrylic urethane clear coatings were prepared as specimens and evaluated for various properties to be applied as top coatings for coil coating. The prepared coatings were excellent in adhesion, excellent in $60^{\circ}$ specular gloss and pencil hardness, and eco-friendly.