• 디지털융복합연구
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• 제18권9호
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• pp.103-112
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• 2020

본 연구의 목적은 한국의 국가채무의 구성요소와 각 구성요소가 국가채무에 미치는 영향을 살펴보는데 있다. 통계청 국가통계포털에서 국가채무를 구성하는 요소로 일반회계 적자보전, 외환시장 안정용, 서민주거 안정용, 지방정부 순채무, 공적자금를 선정하여 검색하였다. 분석기간은 1997년부터 2019년까지 총 23개 연간자료를 이용하였다. 본 연구에서 정리한 자료는 각 구성요소별 전년대비 변동률을 이용하고 있다. 이를 이용하여 본 연구는 지표분석, 수치분석과 모형분석을 시도하였다. 상관분석결과 국가채무는 외환시장안정용, 공적자금 등, 서민주거안정용과 높은 관계를 보이고 있으나 지방정부순채무와는 무관한 관계로 나타났다. 국가채무는 지난 1997년 이후 외환시장안정용과 공적자금 등, 서민주거안정용과 동조화현상을 보이며 지속적으로 증가해 왔다. 2020년도 이후에는 코로나19로 인한 재난지원금 증가로 서민주거안정용과 공적자금 등에서 크게 증가할 것으로 예상되고 있다. 세계적으로 경제상황이 어려운 시점에서 우리나라도 국가재난 지원금의 사용으로 국가부채가 크게 증가할 것으로 보이지만 가능한 경제성장과 금융시장 안정을 위해 효율적으로 운용되기를 기대하고 있다.

• 대한토목학회논문집
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• 제41권5호
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• pp.477-484
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• 2021

최근 기후변화로 인하여 우리나라는 지역에 따라 2~3년 마다 크고 작은 가뭄과 7년 주기의 극한 가뭄이 발생하고 있다. 대부분의 가뭄이 지류 또는 상류의 소규모 용수공급시설이 위치한 지역에서 주로 발생되므로 이 지역에 대한 용수확보 기술에 관한 연구가 필요하다. 본 연구에서는 물공급 취약지역의 하나인 춘천 물로천 유역의 수문학적 가뭄을 조사하기 위해 SPEI, SDI, WBDI를 이용한 가뭄 평가를 수행하였다. 수문학적 가뭄지수인 SPEI와 SDI를 산정한 결과, 공통적으로 2014년에 발생한 가뭄으로 인해 회복되지 못하고 2015년까지 지속된 것을 확인할 수 있었다. WBDI에 의한 수문학적 가뭄지수 평가결과에서는 2014년에 이은 2015년 봄철에 매우 심한가뭄 상태를 보였으며, 2017년 11월에 -1.94로 가장 가뭄이 심했던 것으로 분석되었다. 2003~2019년 (17년)의 월 단위로 산정된 수문학적 가뭄지수를 활용하여 지속기간 및 심도에 따른 코플라 함수를 적용한 이변량 빈도해석 결과, 물로천 유역의 가뭄은 대부분의 10년 빈도 이하의 값으로 나타났으나, 2014년, 2015년, 2019년에 발생한 가뭄의 경우 각각 20년 이상의 재현기간을 갖는 심한가뭄으로 분석되었다.

• Clinical and Experimental Reproductive Medicine
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• 제47권1호
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• pp.77-82
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• 2020

Objective: Irregular patterns of marital cohabitation are a common problem in upper Egypt due to employment conditions. The objective of this study was to investigate the effect of irregular marital cohabitation on the quality of life and sexual function of infertile men. Methods: In total, 208 infertile men were included and divided into two groups. The first group included 134 infertile men with an irregular pattern of marital cohabitation and the second group included 74 infertile men with a regular pattern of marital cohabitation. All subjects were assessed through a clinical evaluation, conventional semen analysis, the fertility quality of life (FertiQoL) questionnaire, the International Index of Erectile Function (IIEF-5) score, and the premature ejaculation diagnostic tool (PMEDT). Results: The two groups were compared in terms of conventional semen parameters, FertiQoL, IIEF-5 score, and PMEDT. Infertile men with an irregular pattern of marital cohabitation had significantly lower subscale and total FertiQoL and IIEF-5 scores. Additionally, they had significantly higher PMEDT scores. Erectile dysfunction and premature ejaculation were more common in them than in infertile men with a regular pattern of marital cohabitation. Conclusion: Irregular patterns of marital cohabitation had an adverse effect on quality of life and sexual function in infertile men.

• Journal of Chest Surgery
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• 제56권6호
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• pp.403-411
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• 2023

Background: The concept of oligo-recurrence has not been generally applied in esophageal cancer. This study aimed to determine the prognostic significance of the number of recurrences in esophageal cancer. Methods: Patients with squamous cell carcinoma who underwent curative esophagectomy with R0 or R1 resection and who experienced a confirmed recurrence were included. The study included 321 eligible participants from March 2001 to December 2019. The relationship between the number of recurrences and post-recurrence survival was investigated. Results: The mean age was 63.8±8.1 years, and the majority of the participants (97.5%) were men. The median time to recurrence was 10.7 months, and the median survival time after recurrence was 8.8 months. Multiple recurrences with simultaneous local, regional, and distant locations were common (38%). In terms of the number of recurrences, single recurrences were the most common (38.3%) and had the best post-recurrence survival rate (median, 17.1 months; p<0.001). Patients with 2 or 3 recurrences showed equivalent survival to each other and longer survival than those with 4 or more (median, 9.4 months; p<0.001). In the multivariable analysis, the significant predictors of post-recurrence survival were body mass index, minimally invasive esophagectomy, N stage, R0 resection, post-recurrence treatment, and the number of recurrences (p<0.05). Conclusion: After esophagectomy, the number of recurrences was the most significant risk factor influencing post-recurrence survival in patients with esophageal cancer. In esophageal cancer, oligo-recurrence can be defined as a recurrence with three or fewer metastases. More intensive treatment might be recommended if oligo-recurrence occurs.

• Structural Engineering and Mechanics
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• 제46권5호
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• pp.629-644
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• 2013

This paper concerns about the raking damages on the ultimate residual hull girder strength of bulk carriers by applying the modified R-D diagram (advanced method). The limited raking damage scenarios, based on the IMO's probability density function of grounding accidents, were carried out by using sampling technique. Recently, innovative method for the evaluation of the structural condition assessment, which covers the residual strength and damage index diagram (R-D diagram), was proposed by Paik et al. (2012). This concept is applied in the present study and modified R-D diagram, which can be considered vessel size effect, is then proposed. Four different types of bulk carrier structures, i.e., Handysize (37K), Supramax (57K), Kamsarmax (82K) and Capesize (181K) by Common Structural Rule (CSR), were applied to draw the general tendency. The ALPS/HULL, intelligent supersize finite element method, was employed for the ultimate longitudinal strength analysis. The obtained empirical formulas will be useful for the condition assessment of bulk carrier structures. It can also cover different sizes of the bulk carriers in terms of ultimate longitudinal strength. Important insights and findings with useful guidelines developed in this study are summarized.

• Journal of Power Electronics
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• 제17권5호
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• pp.1244-1255
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• 2017

The space vector pulse width modulation (SVPWM) technique is a popular PWM method for medium voltage drive applications. Conventional SVPWM (CSVPWM) and bus clamped SVPWM (BCSVPWM) are the most common SVPWM techniques. This paper evaluates the performance of various advanced BCSVPWM strategies in terms of their harmonic distortion and switching loss based on a uniform frame work. A uniform frame work, pulse number captures the performance parameter variations of different SVPWM strategies for various number of samples with heterogeneous pulse numbers. This work compares different advanced BCSVPWM techniques based on the modulation index and location of the clamping position (zero vector changing angle ) of a phase in a line cycle. The frame work provides a fixed fundamental frequency of 50Hz. The different BCSVPWM switching strategies are implemented and compared experimentally on a 415V, 2.2kW, 50Hz, 3-phase induction motor drive which is fed from an IGBT based 2 KVA voltage source inverter (VSI) with a DC bus voltage of 400 V. A low cost PIC microcontroller (PIC18F452) is used as the controller platform.

• Journal of Information Processing Systems
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• 제12권3호
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• pp.525-537
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• 2016

Data hiding is a wide field that is helpful to secure network communications. It is common that many data hiding researchers consider improving and increasing many aspects such as capacity, stego file quality, or robustness. In this paper, we use an audio file as a cover and propose a reversible steganographic method that is modifying the sample values using modulus function in order to make the reminder of that particular value to be same as the secret bit that is needed to be embedded. In addition, we use a location map that locates these modified sample values. This is because in reversible data hiding it needs to exactly recover both the secret message and the original audio file from that stego file. The experimental results show that, this method (measured by correlation algorithm) is able to retrieve exactly the same secret message and audio file. Moreover, it has made a significant improvement in terms of the following: the capacity since each sample value is carrying a secret bit. The quality measured by peak signal-to-noise ratio (PSNR), signal-to-noise ratio (SNR), Pearson correlation coefficient (PCC), and Similarity Index Modulation (SIM). All of them have proven that the quality of the stego audio is relatively high.

• Geomechanics and Engineering
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• 제21권1호
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• pp.11-21
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• 2020

The traditional formulations for estimation of bearing capacity in rock mechanics assume a homogeneous and isotropic rock mass. However, it is common that the rock mass consists of different layers of different rock properties or of the same rock matrix with distinct geotechnical quality levels. The bearing capacity of a heterogeneous rock is estimated traditionally through the weighted average. In this paper, the solution of the weighted average is compared to the finite difference method applied to a bilayer rock mass. The influence of different parameters such as the thickness of the layers, the rock type, the uniaxial compressive strength and the overall geotechnical quality of the rock mass on the bearing capacity of a bilayer rock mass is analyzed. A parametric study by finite difference method is carried out to develop a bearing capacity factor in function of the layer thickness and the rock mass quality expressed in terms of the geological strength index, which is presented in a form of a chart. Therefore, this correlation factor allows estimating the bearing capacity of a rock mass that is formed by two layers with distinct GSI, depending on the bearing capacity of the rock mass formed only by the upper layer and considered by that way as homogenous and isotropic rock mass.

• Geomechanics and Engineering
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• 제21권4호
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• pp.371-377
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• 2020

There are currently three common methods for selecting excavation supports in Polish hard coal mines. While many factors are considered when choosing appropriate support, these do not include layering or cracking in the excavation ceiling. Although global classifications of rock mass are rarely used in hard coal mines, they are utilised much more frequently during the construction of underground structures such as tunnels. Mining classifications of rock mass have been developed (e.g., in Germany) and they rely on a number of factors but are often related to local mining and geological conditions. This paper discusses the selected findings of a study carried out on seven excavation sites with diverse mining and geological characteristics. Based on the collected data, two indicators were developed to describe rock mass quality. The first indicator is referred to as the roof lithology index WL and describes the quality of the excavation roof in terms of its layering and lithology. The second indicator is the crack intensity factor n and represents the amount of cracks in an excavation's roof. The correctness of the developed indicators was supported by reliable data from the excavation in which the designed support did not fulfill its task but was changed at a later stage, after calculating the proposed indicators.

• Journal of Power Electronics
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• 제19권4호
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• pp.968-979
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• 2019

Recently, there has been increased interest in the study of multiphase machines due to their higher fault-tolerant capability when compared to their conventional three-phase counterparts. For six-phase machines, stator windings configured with a single isolated neutral (1N) provide significantly more post-fault torque/power than two isolated neutrals (2N). Hence, this configuration is preferred in applications where post-fault performance is critical. It is well known that min-max injection has been commonly used for three-phase and multiphase machines in healthy condition to maximize the modulation limit. However, there is a lack of discussion on min-max injection for post-fault condition. Furthermore, the effects in terms of the common-mode voltage (CMV) in modulating signals has not been discussed. This paper investigates the effect of min-max injection in post fault-tolerant control on the voltage and speed limit of a symmetrical six-phase induction machine with single isolated neutral. It is shown that the min-max injection can minimize the amplitude of reference voltage, which maximizes the modulation index and post-fault speed of the machine. This in turn results in a higher post-fault power.