• Title/Summary/Keyword: Lee Ha-Bok

Search Result 446, Processing Time 0.031 seconds

Forming Limit Diagram of DP590 considering the Strain Rate (변형률속도를 고려한 DP590의 성형한계도)

  • Kim, Seok-Bong;Ahn, Kwang-Hyun;Ha, Ji-Woong;Lee, Chang-Soo;Huh, Hoon;Bok, Hyun-Ho;Moon, Man-Been
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.18 no.1
    • /
    • pp.127-130
    • /
    • 2010
  • This paper deals with the formability of DP590 steel considering the strain rate. The strain hardening coefficient, elongation and r-value were obtained from the static and dynamic tensile test. As strain rate increases from static to 100/s, the strain hardening coefficient and the uniform elongation decrease and the elongation at fracture and r-value decrease to 0.1/s and increase again to 100/s. The high speed forming limit tests with hemi-spherical punch were carried out using the high speed crash testing machine and high speed forming jig. The high speed forming limit of DP590(order of $10^2$/s) decreases compared to the static forming limit(order of $10^{-3}$/s) and the forming limit band in high speed forming test is narrower than that in the static forming test. This tendency may be due to the development of brittleness with increase of stain rate.

A Study on an ETCS Demand Forecasting Model of Toll Roads in Changwon City (유료도로 ETCS 이용수요 예측모형에 관한 연구 (창원시를 중심으로))

  • Kim, Kyung-Whan;Ha, Man-Bok;Jeon, Yeon-Hoo;Lee, Ik-Su
    • International Journal of Highway Engineering
    • /
    • v.9 no.1 s.31
    • /
    • pp.17-27
    • /
    • 2007
  • Since early 1990s, several developed countries have applied the Electronic Toll Collection System (ETCS) to toll roads in order to solve traffic congestion and delay problems at toll plazas. For the successful operation of the ETCS, it is important to correctly forecast the ETCS using rate. In this study, it was conceived to develop a sophisticated demand forecasting model of the ETCS for toll roads in Changwon City The Binary Logit and neural network models were tested for the model considering 11 explaining variables. The best results in prediction accuracy and goodness-of-fit were obtained on the neural network model. However, because of the difficulty in predicting the 11 variables and its fitness in wide range, the Binary Logit model which considers three policy variables only is recommended as the model to forecast the ETCS using rate.

  • PDF

A Study of SSA Routing Protocol using Utilization Metric in Ad Hoc Networks (Ad Hoc 환경에서의 Utilization Metric을 이용한 SSA 라우팅 프로토콜에 관한 연구)

  • Ji Jong-Bok;Park Joo-Ha;Lee Kaug-Seok;Song Joo-Seok
    • The KIPS Transactions:PartC
    • /
    • v.12C no.4 s.100
    • /
    • pp.543-550
    • /
    • 2005
  • Many routing algorithms, proposed for ad-hoc wireless networks, we based on source routing scheme and shortest path route has short lifetime especially in highly dense ad-hoc wireless networks. So some routing protocols such as SSA and ABR are considering the link stability and try finding more stable route. In this paper we propose a new routing algorithm considering utilization metric based on SSA routing algerian in Ad-Hoc networks. To reduce the bottleneck by specific metric of SSA, proposed scheme makes load balancing in networks by distributing the connections to several routes. For the evaluation of the performance we compare our scheme with existent routing protocol AODV and SSA. And the results, obtained using the ns-2 network simulation platform, show good performance that reduced the number of reconstructions remarkably by distributing the whole traffic to several routes when there are several stable routes.

A Numerical Study of New Vehicle Hydraulic Lift Activation by a Magneto-rheological Valve System for Precise Position Control (정밀 위치 제어를 위해 MR 밸브 시스템을 활용한 차량 유압 리프트에 대한 수치해석적 고찰)

  • Lee, TaeHoon;Park, Jhin-Ha;Choi, Seung-Bok;Shin, Cheol-Soo;Choi, Ji-Young
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.27 no.1
    • /
    • pp.28-35
    • /
    • 2017
  • Recently, conventional hydraulic car lift systems face the technological limitations due to a lack of height control. The demand for height controllability is required in many tasks such as wheel alignment, and requires compensation for the structural deformation of the lift caused by irregular load distribution. In order to resolve this limitation of the conventional car lift, in this work, a new type of a hydraulic vehicle lift using a magneto-rheological (MR) valve system is proposed and analyzed. Firstly, the dynamic model of vehicle lift is formulated to evaluate control performance; subsequently, an MR valve is designed to obtain the desired pressure drop required in the car lift. Next, a proportional-integral-derivative (PID) controller is formulated to achieve accurate control of the lifting height and then computer simulations are undertaken to show accurate height control performances of the proposed new car lift system.

A Basic Study on the Attachment Process of Lightning Leader to Ground (낙뢰 리더의 대지부착과정에 대한 기초적 연구)

  • Yoo, Yang-Woo;Kim, Seung-Min;Kim, You-Ha;Lee, Bok-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.28 no.10
    • /
    • pp.82-88
    • /
    • 2014
  • This paper presents the results of model tests for the attachment process of lightning leader to ground which is one of poorly understood processes of cloud-to-ground lightning discharges. In order to simulate the attachment process of lightning leader to ground, we investigated the discharge characteristics of air gap between the tip of needle-shaped electrode and the soil surface as a parameter of moisture content in soils when the positive and negative $1.2/50{\mu}s$ lightning impulse voltages are applied. The breakdown voltage and the discharge light were observed. As a result, the attachment processes of lightning leader to ground are strongly dependent on the grain size and the moisture content of soils. The time to breakdown was shortened with increasing the magnitude of incident impulse voltages. The delay time from application of the highest voltage to breakdown in sand is shortened with increasing the moisture content. The delay time from application of the voltage to breakdown in gravel varied from about $0.5{\mu}s$ to several ${\mu}s$. As the moisture content in soil increases, the breakdown voltages are decreased and the breakdown voltage versus time to breakdown curves are shifted toward the lower side. The results obtained in this work are similar to those for non-uniform air gap stressed by lightning impulse voltages.

A Case of Nasal T/NK-cell Lymphoma (비강 T/NK 세포형 림프종 1례)

  • Lee, Jung Bok;Jeon, In-sang;Im, Ho Joon;Oh, Young Ha;Kim, Ji Hye
    • Clinical and Experimental Pediatrics
    • /
    • v.46 no.12
    • /
    • pp.1266-1270
    • /
    • 2003
  • The advance of the immunobiology clarifies the nature of non-Hodgkin's lymphoma(NHL). In addition the proceed in the immunophenotyping renders the classification of NHL. According to the Revised European American Lymphoma(REAL) classification, classified by the etiologic factors, molecular biological characteristics, immunophenotype, cytogenetics and histologic feature, nasal T/NK-cell lymphoma(=angiocentric lymphoma) belongs to the category of peripheral T-cell and natural killer cell lymphoma. Nasal T/NK-cell lymphoma is a distinct clinicopathologic entity characterized by progressive necrotic lesions in the nasal cavity, nasopharynx, and palate. The cellular origin of this tumor has been controversial. Although most nasal T/NK-cell lymphomas are of NK-cell lineage, being CD56+, negative for surface CD3(Leu4), and unassociated with rearrangements of the T-cell receptor genes, other minor variants have been reported. This lymphoma is a rare disease and usually experienced in adult. Recently, we experienced a rare type lymphoma, nasal T/NK-cell lymphoma, in 14 years old boy. His soft mass occupied the right nasal cavity including the nasal septum and turbinate. Pathologically this nasal mass showed the infiltration into the vascular wall, illustrating angiodestructive lesion. The cellular origin was NK-cell lineage, being CD56+ and negative to CD3. Now, we report the case with a brief review of related literatures.

Effect of Single or Fractionated X-Irradiation on the NP-SH and NP-SS of Rabbit Liver and Lung Tissues (단회(單回) 및 분획(分劃) X선(線) 조사(照射)가 가토(家兎)의 간(肝) 및 폐조직(肺組織)의 NP-SH 및 NP-SS에 미치는 영향(影響))

  • Park, Soo-Ha;Choi, Kyung-Sook;Kim, Byung-Kwon;Kwon, Yong-Ju;Lee, Jae-Bok
    • The Korean Journal of Physiology
    • /
    • v.4 no.2
    • /
    • pp.61-67
    • /
    • 1970
  • In view of the importance of sulfhydryl groups in producing a chemical protection against ionizing radiation, an attempt was made to evaluate the changes of intrinsic non-protein sulfhydryl (NP-SH) and non-Protein disulfide(NP-SS) of the lung and liver tissues of rabbits following the whole body X-irradiation with 900 r either in single or fractionated $(300\;r{\times}3)$ dose. NP-SH was measured by Ellman's method, and NP-SS was measured by the electrolytic reduction method described by Dohan. Experiment was performed at 1,3,5,24 and 48 hours post·irradiation, and the results were compared with the control. The results thus obtained are summarized as follows; 1) Intrinsic levels of NP-SH and NP-SS of normal rabbits were $0.77{\pm}0.10$ and $0.61{\pm}0.07\;{\mu}mol/gm$ wet weight in liver, and $0.28{\pm}0.03$ and $0.54{\pm}0.03$ in lung tissues respectively. 2) NP-SH of liver after single X-irradiation showed no significant change in general, but at 48 hours post·irradiation, it was elevated comparing with the normal value. 3) Levels of NP-SS in liver was decreased than the normal value in the irradiated groups, and the lowest level was observed at 3 hours after single X-irradiation and at 5 hours after fractionated irradiation. 4) In lung tissues, levels of NP-SS showed no significant change from the control at earlier experimental hours, but a great decrease was observed at later Part of the experiment.

  • PDF

The Switch Installation Criteria For Satisfying Future Reliability Goal (향후 신뢰도 목표를 만족하는 개폐기 설치 기준 제시)

  • Jo, Nam-Hun;O, Jeong-Hwan;Ha, Bok-Nam;Lee, Heung-Ho
    • The Transactions of the Korean Institute of Electrical Engineers A
    • /
    • v.51 no.9
    • /
    • pp.433-440
    • /
    • 2002
  • The addition of switches to a distribution feeder does, in general, increase reliability by decreasing the duration of the outage of many to the customers on the feeder. To cover its service area so that feeder-level delivery reaches sufficiently close to all customers, feeders typically split their routes many times, in what is often called a lateral feeder. It is interesting to note, however, that the effectiveness of a switch is very much dependent on the types of lateral feeder. The types of lateral are classified into two types. The first is loop lateral feeder that can connect its load to an adjacent feeder through a tie line in case that a fault occurs in its feeder and it is laid out so that every feeder has complete fault backup through re-switching of its loads to other sources like a main feeder The second is the radial lateral feeder cannot connect its load to an adjacent line, no provision is made for contingency backup of feeders. There are no other circuits in the radial lateral feeder form which to restore power. In this study, we evaluate the effectiveness of a switch installation between on the radial and loop lateral feeders to increase reliability by decreasing the duration of the outage. These results can help power utility to design the switch layouts on the radial and loop lateral feeder system.

Effects of Stress and Obesity on the Prevalence of Metabolic Syndrome to the Sasang Constitution (체질에 따른 스트레스와 비만도가 대사증후군 유병률에 미치는 영향)

  • Yu, Ha-Na;Kim, Ho-Seok;Lee, Si-Woo;Seo, Bok-Nam;Baek, Young-Hwa
    • Journal of Sasang Constitutional Medicine
    • /
    • v.30 no.1
    • /
    • pp.58-65
    • /
    • 2018
  • Objectives This study is to identify the relationship between stress, obesity and metabolic syndrome (MetS) by Sasang constitution (SC) and to use it as a basic data for the customized healthcare system of chronic disease management. Methods In a cross-sectional study conducted in a rural area of the Gyeongju area in 2014, we extracted data on 1,847 people using data from Korean medicine Data Center (KDC). The SC types diagnosed by Sasang constitutional medicine doctor. The stress was measured by the psychosocial well-being index questionnaire, and the obesity was defined by the body mass index. Results In all SC type, the stress and obesity was associated with MetS. There was a significant difference in the prevalence and trend of MetS according to presence of stress and obesity. The prevalence of MetS was the highest in Taeumin with all the stress and obesity, in order of Soeumin and Soyangin. Regardless SC types, the stress was associated with higher risk of MetS in the obese but not in the nonobese. Conclusion The results of this study indicate that further research is necessary to the SC types for the management of the Metabolic syndrome according to stress and obesity.

PRINCIPAL COMPONENTS BASED SUPPORT VECTOR REGRESSION MODEL FOR ON-LINE INSTRUMENT CALIBRATION MONITORING IN NPPS

  • Seo, In-Yong;Ha, Bok-Nam;Lee, Sung-Woo;Shin, Chang-Hoon;Kim, Seong-Jun
    • Nuclear Engineering and Technology
    • /
    • v.42 no.2
    • /
    • pp.219-230
    • /
    • 2010
  • In nuclear power plants (NPPs), periodic sensor calibrations are required to assure that sensors are operating correctly. By checking the sensor's operating status at every fuel outage, faulty sensors may remain undetected for periods of up to 24 months. Moreover, typically, only a few faulty sensors are found to be calibrated. For the safe operation of NPP and the reduction of unnecessary calibration, on-line instrument calibration monitoring is needed. In this study, principal component-based auto-associative support vector regression (PCSVR) using response surface methodology (RSM) is proposed for the sensor signal validation of NPPs. This paper describes the design of a PCSVR-based sensor validation system for a power generation system. RSM is employed to determine the optimal values of SVR hyperparameters and is compared to the genetic algorithm (GA). The proposed PCSVR model is confirmed with the actual plant data of Kori Nuclear Power Plant Unit 3 and is compared with the Auto-Associative support vector regression (AASVR) and the auto-associative neural network (AANN) model. The auto-sensitivity of AASVR is improved by around six times by using a PCA, resulting in good detection of sensor drift. Compared to AANN, accuracy and cross-sensitivity are better while the auto-sensitivity is almost the same. Meanwhile, the proposed RSM for the optimization of the PCSVR algorithm performs even better in terms of accuracy, auto-sensitivity, and averaged maximum error, except in averaged RMS error, and this method is much more time efficient compared to the conventional GA method.