• Journal of Korean Society of Forest Science
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• v.112 no.4
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• pp.523-529
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• 2023

The aim of this study was to analyze the potential for timber harvesting in the Hongchoen Garisan Leading Forest Management Complex in the national forests, and to suggest an optimal target yield for sustainable timber harvesting. The potential for timber harvesting was assessed by analyzing the area available for timber harvesting using GIS spatial analysis, but excluding areas with a slope of more than 40° (topographical constraints), areas within 30 m on both sides of streams (environmental constraints), and areas more than 300 m away from forest roads (technical constraints). The analysis identified 3,298 ha (49%) of the total complex area of 6,679 ha as available for timber harvesting, yielding a potential harvesting volume of 608,613 m³. In the case of coniferous plantations, the potential harvesting volume was 409,721 m³, which was a very high level that accounted for 67.3% of the total. We also conducted an optimization analysis to minimize the differences in area between age classes, while maintaining sustainable timber harvesting for the next 50 years. An annual average of 41.9 ha (7,988 m³) was determined to be the optimal timber yield, and in this case, it was possible to convert the age class structure to a more stable structure after 50 years.

• Journal of Korean Society of Steel Construction
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• v.10 no.3 s.36
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• pp.487-495
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• 1998

Recently, the space truss has been attracted by many designers because of their ability to support significant loads with a minimum material. And it is relatively flexible to design the configuration of structures. This paper presents a volume optimization for the space truss on the basis of result evaluated from nonlinear analysis. The optimization of the truss is done by nonlinear optimum GINO(General Interactive Nonlinear Optimizer) program. The objective function considered is the volume of the steel bars. The constraints for optimum design are the design limits, such as the axial force strength, maximum slenderness, minimum thickness, allowable deflection and ratio of the external diameter to thickness of the circular tube bars.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.4
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• pp.524-533
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• 2017

This paper presents a novel reset scheme for mm-scale sensing systems with stringent volume and area constraints. In such systems, multi-layer structure is required to maximize the silicon area per volume and minimize the system size. The multi-layer structure requires wirebonding connections for power delivery and communication among layers, but the area overhead for wirebonding pads can be significant. The proposed reset scheme exploits already existing power wires and thus does not require additional wires for system-wide reset operation. To implement the proposed reset scheme, a power management unit is designed to impose reset condition, and a reset detector is designed to interpret the reset condition indicated by the power wires. The reset detector uses a coupling capacitor for the initial power-up and a feedback path to hold the developed supply voltage. The prototype reset detector is fabricated in a $180-{\mu}m$ CMOS process, and the measurement results with the prototype mm-scale system confirmed robust reset operation over a wide range of temperatures and voltages.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.209-214
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• 2007

In Korean geology that crystalline rock is dominant, the properties of subsurface including the anisotropy are distributed complexly and changed abruptly. Because of such geological environments, cross-hole seismic traveltime tomography is widely used to obtain the high resolution image of the subsurface for the engineering purposes in the geotechnical sites. However, because the cross-hole tomography has a wide propagation angle coverage relatively, its data tend to include the seismic velocity anisotropy comparing with the surface seismic methods. It can cause the misinterpretation that the cross-hole seismic data including the anisotropic effects are analyzed and treated with the general processing techniques assuming the isotropy. Therefore, we need to consider the seismic anisotropy in cross-hole seismic traveltime tomography. The seismic anisotropic tomography algorithm, which is developed for evaluation of the velocity anisotropy, includes several inversion schemes in order to make the inversion process stable and robust. First of all, the set of the inversion parameters is limited to one slowness, two ratios of slowness and one direction of the anisotropy symmetric axis. The ranges of the inversion parameters are localized by the pseudo-beta transform to obtain the reasonable inversion results and the inversion constraints are controlled efficiently by ACB(Active Constraint Balancing) method. Especially, the inversion using the Fresnel volume is applied to the anisotropic tomography and it can make the anisotropic tomography more stable than ray tomography as it widens the propagation angle coverage.

• Proceedings of the Safety Management and Science Conference
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• 2006.11a
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• pp.373-383
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• 2006

Logistics is one of the most important factors to manage a stream of materials in economic environment. Establishing effective logistics system needs to consider some constraints which are fluctuation of materials volume, a long distance between makers and consumers, one way logistics and small quantity batch production. It is estimated that Unit Load System should be a powerful method to cope with those problems. It helps to realize the key issues which are Standardization and Logistics Pool System The Material Unification of Logistics System is able to participate in all kinds of industries including manufacturing, distribution and logistics. This system has some merits which are a long distance transportation cost down, product recovery, and treatment in the unbalance of demand and supply caused by unstable materials volume. Four strategies of Material Logistics Model are Packing Rationalization, Logistics Pool System, JIT System application and establishing effective infrastructure. The Material Unification Of Logistics System based on Unit Load System achieves efficiency of logistics and largely decreases moving cost.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.1
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• pp.21-28
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• 2020

Integrated bidirectional OBC/LDC was developed to reduce the volume for elements, avoid space restriction, and increase efficiency in EV vehicles. In this study, a DC-DC converter in integrated OBC/LDC circuits was composed of an SRC circuit with a stable output voltage relative to an LLC circuit using a theoretical method and simulation. The resonant network of the selected circuit was optimized to minimize the power loss and element volume under constraints for the buck converter and the battery charging range. Moreover, the validity of the optimal model was verified through an analysis using a theoretical method and a numerical analysis based on power loss at the optimized resonant frequency.

• International Journal of Highway Engineering
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• v.15 no.6
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• pp.125-133
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• 2013

PURPOSES : The purpose of this study is to propose delay-minimizing operation methodology of a signalized intersection based upon optimization of lane-uses on approaching lanes for an intersection. METHODS : For the optimization model of lane-uses, a set of constraints are set up to ensure feasibility and safety of the lane-uses, traffic flow, and signal settings. Minimization of demand to saturation flow ratio of a dual-ring signal control system is introduced to the objective function for delay minimization and effective signal operation. Using the optimized lane-uses, signal timings are optimized by delay-based model of TRANSYT-7F. RESULTS : It was found that the proposed objective function is great relation with delay time for an intersection. From the experimental results, the method was approved to be effective in reducing delay time. Especially, cases for two left-turn lanes reduced greater delays than those for a left turn lane. It is noticed that the cases for different traffic volume by approach reduced greater delays than those for the same traffic volume by approach. CONCLUSIONS : It was concluded that the objective function is proper for lane-uses optimizing model and the operation method is effective in reducing delay time for signalized intersections.

• Progress in Medical Physics
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• v.21 no.3
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• pp.298-303
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• 2010

The aim of this study was to compare the dose distribution of intensity modulated radiation therapy (IMRT) with 3 dimensional conformal radiation therapy (3DCRT) in prostate cancer. The IMRT plan and the 3DCRT plan used the 9 fields technique, respectively. In IMRT, tumor dose was a total dose of 66 Gy at 2.0 Gy per day, 5 days a week for 5 weeks. All cases were following the dose volume histogram (DVH) constraints. The maximum and minimum tumor dose constraints were 6,700 cGy and 6,500 cGy, respectively. The rectum dose constraints were <35% over 50 Gy. The bladder dose constraints were <35% over 40 Gy. The femur head dose constraints were <15% over 20 Gy. Tumor dose in the 3DCRT were 66 Gy. In IMRT, the maximum dose of PTV was 104.4% and minimum dose was 89.5% for given dose. In 3DCRT, the maximum dose of PTV was 105.3% and minimum dose was 85.5% for given dose. The rectum dose was 34.0% over 50 Gy in IMRT compared with 63.3% in 3DCRT. The bladder dose was 30.1% over 40 Gy in IMRT compared with 30.6% in 3DCRT. The right femur head dose was 9.5% over 20 Gy in IMRT compared with 17.5% in 3DCRT. The left femur head dose was 10.6% over 20 Gy in IMRT compared with 18.3% in 3 DCRT. The dose of critical organs (rectum, bladder, and femur head) in IMRT showed to reduce than dose of 3DCRT. The rectum dose over 50 Gy in IMRT was reduced 29.3% than 3DCRT. The bladder dose over 40 Gy in IMRT was similar to 3DCRT. The femur head dose over 20 Gy in IMRT was reduced about 7~8% than 3DCRT.

• Radiation Oncology Journal
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• v.32 no.1
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• pp.23-30
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• 2014

Purpose: The goal of this study is to determine whether the magnitude of overlap between planning target volume (PTV) and rectum ($Rectum_{overlap}$) or PTV and bladder ($Bladder_{overlap}$) in prostate cancer volumetric-modulated arc therapy (VMAT) is predictive of the dose-volume relationships achieved after optimization, and to identify predictive equations and cutoff values using these overlap volumes beyond which the Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC) dose-volume constraints are unlikely to be met. Materials and Methods: Fifty-seven patients with prostate cancer underwent VMAT planning using identical optimization conditions and normalization. The PTV (for the 50.4 Gy primary plan and 30.6 Gy boost plan) included 5 to 10 mm margins around the prostate and seminal vesicles. Pearson correlations, linear regression analyses, and receiver operating characteristic (ROC) curves were used to correlate the percentage overlap with dose-volume parameters. Results: The percentage $Rectum_{overlap}$ and $Bladder_{overlap}$ correlated with sparing of that organ but minimally impacted other dose-volume parameters, predicted the primary plan rectum $V_{45}$ and bladder $V_{50}$ with $R^2$ = 0.78 and $R^2$ = 0.83, respectively, and predicted the boost plan rectum $V_{30}$ and bladder $V_{30}$ with $R^2$ = 0.53 and $R^2$ = 0.81, respectively. The optimal cutoff value of boost $Rectum_{overlap}$ to predict rectum $V_{75}$ >15% was 3.5% (sensitivity 100%, specificity 94%, p < 0.01), and the optimal cutoff value of boost $Bladder_{overlap}$ to predict bladder $V_{80}$ >10% was 5.0% (sensitivity 83%, specificity 100%, p < 0.01). Conclusion: The degree of overlap between PTV and bladder or rectum can be used to accurately guide physicians on the use of interventions to limit the extent of the overlap region prior to optimization.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.335-342
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• 2005

Using higher order Mindlin plates and piezoelectric materials, eigenvalue problems are considered. Since piezoelectric crystal resonators produce a proper amount of electric signal for a thickness-shear frequency, the objective is to decouple the thickness-shear mode from the others. Design variables are the bulk material densities corresponding to the mass of masking plates for electrodes. The design sensitivity expressions for the thickness-shear frequency and mode shape vector are derived using direct differentiation method(DDM). Using the developed design sensitivity analysis (DSA) method, we formulate a topology optimization problem whose objective function is to maximize the thickness-shear component of strain energy density at the thickness-shear mode. Constraints are the allowable volume and area of masking plate. Numerical examples show that the optimal design yields an improved mode shape and thickness-shear energy.