• Journal of Korean Society of Forest Science
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• v.101 no.3
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• pp.344-355
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• 2012

This study was conducted to analyze on the operational time and productivities of logging operations in whole-tree logging operation system by tower-yarder and swing-yarder, and in cut-to-length logging operation system by excavator with grapple in order to establish the efficient logging operation system and to spread logging operation technique. In the analysis of operational time, in case of whole-tree logging operation system, the felling time was 46.6 sec/cycle by chain saw, the yarding time was 480.6 sec/cycle by tower-yarder, the yarding time was 287.4 sec/cycle by swing-yarder and the bucking time was 155.14 sec/cycle by chain saw. In case of the cut-to-length logging operation system, the felling and bucking time was 225.65 sec/cycle by chain saw, the cut-to-length extraction time was 4,972 sec/cycle by excavator with grapple, the branches and leaves extraction time was 3,143 sec/cycle by excavator with grapple. The forwarding time was 4,688 sec/cycle by wheel type mini-forwarder, the forwarding time was 2,118 sec/cycle by excavator with grapple and small forwarding vehicle. In the analysis of operational productivities, in case of whole-tree logging operation system, the average felling performance was $57.89m^3/day$ by chain saw, the average yarding performance was $20.3m^3/day$ by tower-yarder, $31.55m^3/day$ by swing-yarder respectively, the average bucking performance was $20.3m^3/day$ by chain saw. In case of the cut-to-length logging operation system, the average felling and bucking performance was $11.96m^3/day$ by chain saw, the average cut-to-length extraction performance was $34.75m^3/day$ by excavator with grapple, the average branches and leaves extraction performance was $37.66m^3/day$ by excavator with grapple, the average length of operation road construction was 73.8 m/day by excavator with grapple. The average forwarding performance by wheel type mini-forwarder and the average forwarding performance by excavator with grapple and small forwarding vehicle was $15.73m^3/day$ and $65.03m^3/day$, respectively.

• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1190-1199
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• 2020

The purpose of this study is to analyze the variables affecting the effective stroke in the swing performed through 12 weeks of training for golf beginners, and to provide basic data on the effective stroke factors for the golf beginners to settle on the fairway. Twenty subjects were participate in the study (age: 21.35±1.69 yrs, height: 176.75±7.99 cm, weight: 70.70±9.76 kg). All subjects were subjected to a 12-week golf training, and trackman 4 was used in the 12th week to calculate variables affecting the effective stroke during a golf swing. Trackman data was divided into club-variables and ball-variables, and a binary logistic regression analysis was performed to find out the variables affecting effective strokes. In club-variables, high dynamic loft and low face angles were found in effective stroke, and in ball-variables, fast ball speed, large smash factor, high launch angle, and many spin rates were also found in effective stroke. As a result of the binary logistic regression analysis of club-variables, the probability of an effective stroke increased as the club speed and dynamic loft increased, and the probability of an effective stroke decreased as the face angle increased. The influence of effective stroke in the club-variables was in the order of dynamic loft, face angle, and club speed. In the ball-variable, the probability of an effective stroke increased when the lunch angle increased, and the probability of an effective stroke decreased as the lunch direction increased. As a condition to increase the probability of effective stroke based on the results, it is necessary to increase the club speed through high dynamic loft and low face angle during swing through continuous practice. Through this, the probability of effective stroke through increasing the launch angle and decreasing the launch direction will increase.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.583-589
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• 2017

The 1900s in New Orleans, the harbor city, was indeed an era of confusion because there were various ethnic groups and races. Songs that had been sung by slaves taken from Africa, Black spiritual music, blues, British folk songs, French folk music, ballet music, Spanish dance music, and the march of military bands were mixed with Rag Time to achieve diversity. This developed the beginning of jazz. While swing jazz was most popular and loved by the public during the 20th century, the bebop preferred the small scale organization of musical instruments and developed as a form of jazz featuring the impromptu musical performances. Later, cool jazz, a new style involving the fast and complicated code progress, emerged with free jazz, which features the fundamental rupture from the tradition of the jazz. Miles Davis, who introduced the rock beat in jazz, started fusion jazz. Although jazz has been named differently depending on the era, the main attraction of jazz lies on improvisation. In other words, despite a small changes in code progress and rhythm, the most important thing the player considers is improvisation. Some famous players who lived in the same era followed the whole atmosphere but each had their own style. So, even when they did play the same song, they revealed their style in solo parts despite the same head.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.3
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• pp.479-485
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• 2006

The double gate(DG) MOSFET is a promising candidate to further extend the CMOS scaling and provide better control of short channel effect(SCE). DGMOSFETs, having ultra thin undoped Si channel for SCEs control, ale being validated for sub-20nm scaling. A novel analytical transport model for the subthreshold mode of DGMOSFETs is proposed in this paper. The model enables analysis of short channel effect such as the subthreshold swing(SS), the threshold voltage roil-off$({\Delta}V_{th})$ and the drain induced barrier lowering(DIBL). The proposed model includes the effects of thermionic emission and quantum tunneling of carriers through the source-drain barrier. An approximative solution of the 2D Poisson equation is used for the distribution of electric potential, and Wentzel-Kramers-Brillouin approximation is used for the tunneling probability. The new model is used to investigate the subthreshold characteristics of a double gate MOSFET having the gate length in the nanometer range $(5-20{\sim}nm)$ with ultra thin gate oxide and channel thickness. The model is verified by comparing the subthreshold swing and the threshold voltage roll-off with 2D numerical simulations. The proposed model is used to design contours for gate length, channel thickness, and gate oxide thickness.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.12
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• pp.1193-1199
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• 2012

A cup burner experiment was performed to investigate the effect of the oxidizer velocity and concentration on flame instability near extinction. Heptane was used as a fuel and air diluted by nitrogen and carbon dioxide was used in the oxidizer stream. Two types of flame instabilities at the flame base and at axial downstream were observed near extinction. The instability at the flame base could be characterized by cell, swing, and rotation modes, and the cell mode changed to the rotation mode through the swing mode as the oxidizer velocity increased. To assess the parameters for the flame instability, the initial mixture strengths, Lewis number, and adiabatic flame temperature were investigated under each condition. The Lewis number might be the most important among them, but it is impossible to generalize because of the insufficient number of cases. Furthermore, the axial periodic flickering motion disappeared at low and high oxidizer velocities near extinction. This resulted from the fact that low oxidizer velocity induced evaporated fuel velocity below the critical velocity and high velocity made the reacting fuel velocity comparable.

• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.77-85
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• 2009

This study is aimed at providing information on injury prevention and skill improvement by inducing the accurate movements in exercise as well as understanding the principles of badminton drive movements. Movement displacement of racket head showed the similar patterns among those surveyed but, it seemed that slight differences resulted from external factors such as height, length of brachial and forearm and individual trend of swing locus. Regarding upper joint angle per phase, the angles of shoulder joint, elbow joint and wrist joint were closely associated in taking drive movements and they supported the segment order theory that power was conveyed from proximal into distal. It was shown that angular velocity of upper joint became larger in follow through movement after impact among all those surveyed, which meant the importance of follow through in racket sports such as badminton. In conclusion, this follow through movement acts as an important factor in racket sports in terms of pose stability maintenance, pose correction of movements and injury prevention of joints. In summary, when swings are made according to segment order theory, efficient movements can be taken.

• Journal of Korean Society of Forest Science
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• v.102 no.2
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• pp.229-238
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• 2013

This study was conducted to analyze on the operational cost of logging operations in the whole-tree logging operation system by tower-yarder and swing-yarder, and in the cut-to-length logging operation system by excavator with grapple in order to spread efficient logging operation technique and to establish the logging operation system. In the results of the analysis of operation cost, in case of the whole-tree logging operation system, the operation cost was 2,099 won/$m^3$ in felling by chain saw, 28,286 won/$m^3$ in yarding by tower-yarder, 18,265 won/$m^3$ in yarding by swing-yarder, 18,939 won/$m^3$ in bucking by excavator with grapple and chain saw, 20,484 won/$m^3$ in forwarding and accumulation by wheel type mini-forwarder, 12,701 won/$m^3$ in forwarding and accumulation by excavator with grapple and small forwarding vehicle. In case of the cut-to-length logging operation system, the operation cost was 10,160 won/$m^3$ in felling and bucking by chain saw, 7,567 won/$m^3$ in cut-to-length extraction by excavator with grapple, 6,982 won/$m^3$ in branches and leaves extraction by excavator with grapple, 3,040 won/$m^3$ in the operation road construction by excavator with grapple, 20,484 won/$m^3$ in forwarding and accumulation by wheel type mini-forwarder, 12,701 won/$m^3$ in forwarding and accumulation by excavator with grapple and small forwarding vehicle.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.2
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• pp.144-151
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• 2022

In this paper, a 1.5V 256kb eFlash memory IP with low area DC-DC converter is designed for battery application. Therefore, in this paper, 5V NMOS precharging transistor is used instead of cross-coupled 5V NMOS transistor, which is a circuit that precharges the voltage of the pumping node to VIN voltage in the unit charge pump circuit for the design of a low-area DC-DC converter. A 5V cross-coupled PMOS transistor is used as a transistor that transfers the boosted voltage to the VOUT node. In addition, the gate node of the 5V NMOS precharging transistor is made to swing between VIN voltage and VIN+VDD voltage using a boost-clock generator. Furthermore, to swing the clock signal, which is one node of the pumping capacitor, to full VDD during a small ring oscillation period in the multi-stage charge pump circuit, a local inverter is added to each unit charge pump circuit. And when exiting from erase mode and program mode and staying at stand-by state, HV NMOS transistor is used to precharge to VDD voltage instead of using a circuit that precharges the boosted voltage to VDD voltage. Since the proposed circuit is applied to the DC-DC converter circuit, the layout area of the 256kb eFLASH memory IP is reduced by about 6.5% compared to the case of using the conventional DC-DC converter circuit.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.380-388
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• 2023

This study estimates the metacentric height (GM) of a model ship by varying the transverse weight distribution, considering the effects of the roll period and moment of inertia, and compares it with the GM values measured by the inclining test. In the process, the relationship between the values is analyzed. Three types of ships-a 7-ton fishing vessel, 20-ton fishing vessel, and KRISO Very Large Crude-oil Carrier (KVLCC)-were used for the experiment and comparison. The roll period and moment of inertia were measured using the free roll decay and swing frame tests, and the GM was measured using inclining test. The estimated GM from the roll period and moment of inertia showed the same trend as the GM measured using the inclining test in the change of the weight distribution. However, the GM values measured using the inclining test were lower. Therefore, additional correction factors or parameters other than the roll period and moment of inertia are necessary for estimating GM. In the future, the relationship between the weight center and the estimated GM will be analyzed to derive the correction factors.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.751-754
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• 2008

본 연구에서는 나노구조 FinFET 제작시 게이트산화막 특성이 서브문턱영역에서 전송특성에 미치는 영향을 분석하고자 한다. 이를 위하여 분석학적 전송모델을 사용하였으며 분석학적 모델을 유도하기 위하여 포아슨방정식을 이용하였다. 나노구조 FinFET에서 문턱전압이하의 전류전도에 영향을 미치는 열방사전류와 터널링전류에 대하여 분석하였으며 본 연구의 모델이 타당하다는 것을 입증하기 위하여 서브문턱스윙값을 이차원 시뮬레이션값과 비교하였다. 결과적으로 본 연구에서 제시한 전송특성모델이 이차원 시뮬레이션모델과 매우 잘 일치하였으며 FinFET의 전송특성이 게이트산화막의 특성에 따라 매우 큰 변화를 보이는 것을 알 수 있었다. 특히 게이트길이가 작아지면서 전송특성에 커다란 영향을 미치는 터널링특성에 대하여 집중적으로 분석하였다.