• Journal of Korean Society of Forest Science
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• v.112 no.1
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• pp.83-92
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• 2023

This study was established to investigate the site environment of mixed forests in Korea and to estimate the growth and yield of stands using national forest resources inventory data. The growth of mixed forests was derived by applying the Chapman-Richards model with diameter at breast height (DBH), height, and cross-sectional area at breast height (BA), and the yield of mixed forests was derived by applying stepwise regression analysis with factors such as cross-sectional area at breast height, site index (SI), age, and standing tree density per ha. Mixed forests were found to be growing in various locations. By climate zone, more than half of them were distributed in the temperate central region. By altitude, about 62% were distributed at 101-400 m. The fitness indexes (FI) for the growth model of mixed forests, which is the independent variable of stand age, were 0.32 for the DBH estimation, 0.22 for the height estimation, and 0.18 for the basal area at breast height estimation, which were somewhat low. However, considering the graph and residual between the estimated and measured values of the estimation equation, the use of this estimation model is not expected to cause any particular problems. The yield prediction model of mixed forests was derived as follows: Stand volume =-162.6859+6.3434 ∙ BA+9.9214 ∙ SI+0.7271 ∙ Age, which is a step- by-step input of basal area at breast height (BA), site index (SI), and age among several growth factors, and the determination coefficient (R²) of the equation was about 96%. Using our optimal growth and yield prediction model, a makeshift stand yield table was created. This table of mixed forests was also used to derive the rotation of the highest production in volume.

• Journal of Korean Society of Forest Science
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• v.111 no.1
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• pp.136-149
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• 2022

In this study, the performance of a nonlinear mixed-effects (NLME) model used to estimate the stem taper of Pinus densiflora in Gangwon Province was compared with that of a nonlinear fixed-effects (NLFE) model using several performance measures. For the diameters of whole tree stems, the NLME model improved on the performance of the NLFE model by 26.4%, 42.9%, 43.1%, and 0.9% in terms of BIAS, MAB, RMSE, and FI, respectively. For the cross-section areas of whole tree stems, the NLME model improved on the performance of the NLFE model by 67.7%, 44.7%, 45.8%, and 1.0% in terms of BIAS, MAB, RMSE, and FI, respectively. Based on the analysis of 12 relative height classes of tree stems, stem taper estimation performance was also reasonably improved by the NLME model, which showed better MAB, RMSE, and FI at every relative height class compared with those of the NLFE model. In some classes, the NLFE model had better BIAS than the NLME model (stem diameter: 0.05, 0.2, 0.3, and 0.8; stem cross-section area: 0.05, 0.3, 0.5, 0.6, and 1.0). However, the NLME model enhanced the performance of stem diameter and cross-section area estimations at the lowest stem part (0.2 m from the ground). Improvements for stem diameter in terms of BIAS, MAB, RMSE, and FI were 84.2%, 69.8%, 68.7%, and 3.1%, respectively. For stem cross-section areas, the improvements in BIAS, MAB, RMSE, and FI were 98.5%, 70.1%, 68.7%, and 3.1%, respectively. The cross-section area at 0.2 m from the ground occupied 22.7% of total cross-section area. Improvements in estimation of cross-section area at the lowest stem part indicate that stem volume estimation performance could also be enhanced. Although NLME models are more difficult to fit than NLFE models, the use of NLME models as a standard method for the estimating the parameters of stem taper equations should be considered.

• Journal of Environmental Health Sciences
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• v.46 no.2
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• pp.204-213
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• 2020

Objective: This study is aimed at investigating indoor air quality on public transportation (subway, train, and bus) according to changes in season and time. Methods: We evaluated TVOC and HCHO on public transportation based on the un-controlled parameters of the Ministry of Environment. We also measured temperature and humidity since they affect the concentration of TVOC and HCHO. For public transportation classification, subway lines were classified into Lines 1 to 4. Additionally, trains were classified as ITX and KTX. Results: When comparing summer and winter on public transportation, the concentrations of TVOC and HCHO did not show any particular tendency. However, the concentrations of TVOC and HCHO during traffic congestion was higher than levels during times of non-congestion on most public transportation. In summer and winter, the measurement results for temperature and humidity showed a normal range, so temperature and humidity did not affect the concentrations of TVOC and HCHO. In the case of TVOC, TVOC concentrations on new trains were found to be relatively higher than on older ones, but there was no statistically correlation. Conclusions: A survey was conducted on the indoor air quality on public transportation. This study also analyzed data based on TVOC and HCHO for designing policies and managing indoor air quality.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.259-266
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• 2017

The purpose of this study is to investigate female students in Engineering college and suggest the improvement for the program of Career Development Center of female College Student. The survey was administered to 167 female college students to examine their preparation of employment. In the results, first, the level of career efficacy was average and interest in the majors was slightly lowe than average. In addition, the degree of desire to be employed in the field related to the major showed an average level. Second, they choose the practical ability as the most required and lack of. Third, satisfaction with the support of the University for career was low, but satisfaction with the interview preparation program was highest. Finally, this study proposed improvement of programs for Career Development Center of female College Student.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.527-536
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• 2018

In this paper, we developed a prototype model accident management SMART-Navigation project. In order to develop a prototype model, we analyzed the status of maritime data exchange standard and procedure. We developed accident management prototype application schema, feature catalog and portrayal catalog in accordance with S-100 standard data model development procedure by collecting requirements related services and referring to related standards. In order to verify accident management prototype model, we test data set based on Gwang-yang Port. The prototype model and test data verified verification software, and it was confirmed that the designated symbol was displayed at the correct position through the S-100 simple viewer.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.6
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• pp.689-702
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• 2019

This paper deals with the verification of the functions about mining robot, which is the system for developing deep seabed resources by applying V&V(verification and validation). In order to overcome water pressure of 500 bar and to travel on soft ground, and to operate in deep sea environment with bad conditions, it is necessary to develop a robot that can satisfy various deepsea conditions. A mining robot has been developed based on simulation based design and Multidisciplinary design optimization. In order to verify the developed robot, lab test and real sea test should be performed for various marine environment conditions. There are too many requirements to consider, such as space, time, cost, personnel, and environment to do performance test. So it is costly and time consuming for developing robot. In order to solve this problems, V&V technique was applied to mining robot. The stages of mining robot design, fabrication and commission were verified.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.07a
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• pp.263-264
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• 2016

이메일은 모바일 기기의 발달과 SNS의 확산에도 불구하고 전 세계의 기업에게 가장 중요한 통신 및 업무수단으로 여전히 중요한 역할을 하고 있다. 이메일의 사용 증가로 인해 보안 및 보관 문제가 발생하였으며, 모든 이메일을 수년에 걸쳐 보관할 의무를 지는 기업이 점점 늘어나고 있다. 본 논문에서는 의미추론규칙을 이용하여 온톨로지 기반의 이메일 아카이빙 시스템에 대해 제안한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.07a
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• pp.293-294
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• 2016

스마트폰, 블랙박스, CCTV 등을 통해 다양하고 방대한 영상 데이터가 발생하고 있다. 그중에서 사람의 얼굴 영상을 통해 개인을 인식 및 식별하고 감정 상태를 분석하려는 다양한 연구가 진행되고 있다. 본 논문에서는 디지털영상처리 분야에서 널리 사용되고 있는 SIFT알고리즘을 이용하여, 얼굴영상에 대한 특징점을 추출하고 이를 기반으로 성별, 나이 및 기초적인 감정 상태를 분류할 수 있는 시스템을 제안한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.1
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• pp.44-52
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• 2017

This paper describes a 100 kW high-efficiency isolated DC-DC converter for DC distribution system. The DC-DC converter consists of two dual-active-bridge (DAB) converters in parallel. The operating principle of the DAB converter is explained, and the algorithm for parallel operation of the DAB converters is proposed. Simulation and experiments are conducted to verify the performance of the proposed system. Experimental results demonstrate that the developed converter excellently marks 97.4 percent of peak efficiency under its normal operating condition.

• Journal of Korea Multimedia Society
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• v.19 no.5
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• pp.826-836
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• 2016

Mastering a musical instrument for an unskilled beginning learner is not an easy task. It requires playing every note correctly and maintaining the tempo accurately. Any music comes in two forms, a music score and it rendition into an audio music. The proposed method of assisting beginning music players in both aspects employs two popular pattern recognition methods for audio-visual analysis; they are support vector machine (SVM) for music score recognition and hidden Markov model (HMM) for audio music performance tracking. With proper synchronization of the two results, the proposed music learning assistant system can give useful feedback to self-training beginners.