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Research Trends in Hybrid Cross-Laminated Timber (CLT) to Enhance the Rolling Shear Strength of CLT (CLT의 rolling shear 향상을 위한 hybrid cross laminated timber 연구 동향)

  • YANG, Seung Min;LEE, Hwa Hyung;KANG, Seog Goo
    • Journal of the Korean Wood Science and Technology
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    • v.49 no.4
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    • pp.336-359
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    • 2021
  • In this study, hybrid CLT research and development trends were analyzed to improve the low rolling shear strength of CLT, a large wooden panel used in high-rise wooden buildings. Through this, basic data that can be used in research and development directions for localization of CLT were prepared. As a way to improve the low rolling shear strength, the use of hardwood lamina, the change of the lamina arrangement angle, and the use of structural composite materials are mainly used. Rolling shear strength and shear modulus of hardwood lamina are more than twice as high as softwood lamina. It confirmed that hardwoods can be used and unused species can be used. Rolling shear strength 1.5 times, shear modulus 8.3 times, bending stiffness 4.1 times improved according to the change of the layer arrangement angle, and the CLT strength was confirmed by reducing the layer arrangement angle. Structural wood-based materials have been improved by up to 1.35 times MOR, 1.5 times MOE, and 1.59 times rolling shear strength when used as laminas. Block shear strength between the layer materials was also secured by 7.0 N/mm2, which is the standard for block shear strength. Through the results of previous studies, it was confirmed that the strength performance was improved when a structural wood based materials having a flexural performance of MOE 7.0 GPa and MOR 40.0 MPa or more was used. This was determined based on the strength of layered materials in structural wood-based materials. The optimal method for improving rolling shear strength is judged to be the most advantageous application of structural wood based materials with strength values according to existing specifications. However, additional research is needed on the orientation of CLT lamina arrangement according to the fiber arrangement of structural wood-based materials, and the block shear strength between lamina materials.

Estimation of carbon storage in reclaimed coal mines: Focused on Betula platyphylla, Pinus koraiensis and Pinus spp. plantations (폐탄광 산림복구지의 수종별 탄소 저장량 추정: 자작나무, 잣나무, 소나무류 식재지를 중심으로)

  • Kim, Gwangeun;Kim, Seongjun;Kim, Hyun-Jun;Chang, Hanna;Kim, Hyungsub;Park, Yong-Ha;Son, Yowhan
    • Korean Journal of Environmental Biology
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    • v.38 no.4
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    • pp.733-743
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    • 2020
  • We estimated the carbon storage of coal mines reclaimed using Betula platyphylla (BP), Pinus koraiensis (PK), and Pinus spp. (PS, Pinus densiflora, Pinus rigida, and Pinus thunbergii). The carbon storage of tree biomass (TB), forest floor(FF), mineral soil (MS), and the total forest were quantified. Reclaimed sites were located in Gangwon-do, Gyeongsangbuk-do, and Jeollanam-do; reclamation was conducted at various times in each region. The carbon storage (ton C ha-1) in FF (BP: 3.31±0.59, PK: 3.60±0.93, PS: 4.65±0.92), MS (BP: 28.62±2.86, PK: 22.26±5.72, PS: 19.95±3.90), and the total forest(BP: 54.81±7.22, PK: 47.29±8.97, PS: 45.50±6.31) were lower than that of natural forests (NF). The carbon storage in TB was lower in BP (22.57±6.18) compared to NF, while those in PK(21.17±8.76) and PS (20.80±6.40) were higher than in NF. While there were no significant differences in the carbon storage of TB, FF, and the total forest among tree species, results from MS showed a significant difference among species. TB and the total forest carbon storages in all sites increased after reclamation. Soil pH and cation exchange capacity values in BP and PS were lower than in NF. Amounts of labile carbon, available phosphate, and microbial biomass carbon in reclaimed sites were less than half of NF. There are a number of methods that could increase the reclamation efficiency. Applications of lime or organic fertilizers, as well as tillage operations, may improve soil properties in reclaimed coal mines. Additionally, pruning and thinning would increase tree growth thereby increasing carbon storage.

Characterization of compounds and quantitative analysis of oleuropein in commercial olive leaf extracts (상업용 올리브 잎 추출물의 화합물 특성과 이들의 oleuropein 함량 비교분석)

  • Park, Mi Hyeon;Kim, Doo-Young;Arbianto, Alfan Danny;Kim, Jung-Hee;Lee, Seong Mi;Ryu, Hyung Won;Oh, Sei-Ryang
    • Journal of Applied Biological Chemistry
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    • v.64 no.2
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    • pp.113-119
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    • 2021
  • Olive (Olea europaea L.) leaves, a raw material for health functional foods and cosmetics have abundant polyphenols including oleuropein (major bioactive compound) with various biological activities: antioxidant, antibacterial, antiviral, anticancer activity, and inhibit platelet activation. Oleuropein has been reported as skin protectant, antioxidant, anti-ageing, anti-cancer, anti-inflammation, anti-atherogenic, anti-viral, and anti-microbial activity. Despite oleuropein is the important compound in olive leaves, there is still no quantitative approach to reveal oleuropein content in commercial products. Therefore, a validated method of analysis has to develop for oleuropein. In this study, the components and oleuropein content in 10 types of products were analyzed using a developed method with ultra-performance liquid chromatography to quadrupole time-of-flight mass spectrometry, charge of aerosol detector, and photodiode array. The total of 18 compounds including iridoids (1, 3, 4, 14, and 16-18), coumarin (2), phenylethanoids (5, 9, and 11), flavonoids (6-8, 10, 12, and 13), lignan (15), were tentatively identified in the leaves extract based high resolution mass spectrometry data, and the content of oleuropein in each product was almost identical between two detection methods. The oleuropein in three commercial product (A, G, H) was contained more over the suggested content, and it of five products (B, E, H, I, J) were analyzed within 5-10% error range. However, the two products (C, D) were found far lower than suggested contents. This study provides that analytical results of oleuropein could be a potential information for the quality control of leaf extract for a manufactured functional food.

The Influence of Senior Entrepreneurship Competency and Start-up Support Policy on Entrepreneurship Intention: Focusing on the Moderating Effect of Mentoring (시니어 창업자 역량과 창업지원정책이 창업의지에 미치는 영향: 멘토링의 조절효과를 중심으로)

  • Kim, Young Tae;Heo, Chul Moo
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.16 no.2
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    • pp.109-121
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    • 2021
  • With the recent increase in senior retirement, and senior start-ups are becoming more active due to high interest in start-ups. Research on young entrepreneurship, including college students, is being actively conducted, but most of the preceding research on senior entrepreneurship was conducted mainly on personal characteristics and social environment, and there were not many empirical studies on the influencing factors of entrepreneurship support policies. In this study, research and discussion on the entrepreneurial support policy and entrepreneurial competence as the influencing factors of senior entrepreneurship. As the independent variable of this study, the founder's competency was adopted as two factors: technical competence and creative competency, and the entrepreneurial support policy was divided into education support and funding support. Mentoring was set as a controlling variable and entrepreneurial intention was set as a dependent variable. A total of 232 questionnaires collected from seniors in their 40s or older were empirically analyzed. To verify the hypothesis of the study, SPSS 23 was used for exploratory factor analysis and regression analysis, and Process 3.4 was used for moderation effect. As a result of the study, it was found that the factors of technical competence, creative competence, educational support, and funding all have a significant influence on the will of entrepreneurship. It was found that creative competency(𝛽=.318), funding support(𝛽=.188), educational support(𝛽=.152), and technical competence(𝛽=.139), in this order, influenced the entrepreneurial intention. It was verified that the moderating effect of mentoring was significant between technical competence, creative competence, and entrepreneurial intention, but the moderating effect of mentoring between educational support, funding and entrepreneurial intention was not. The implications of this study will contribute to the research of senior start-up support policies, institutional supplementation, and differentiated start-up support programs by studying the factors of senior start-up capabilities and start-up support policies. It is also believed that it will contribute to the search for ways to increase creative capabilities that have a high influence on the willingness to start a business and the expansion of mentoring functions.

Consistency Analysis of Intermediate Soil Based on the Fines Contents (세립분 함유율에 따른 중간토의 컨시스턴시 분석)

  • Oh, Sewook;Bae, Wooseok;Bang, Seongtaek
    • Journal of the Korean GEO-environmental Society
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    • v.22 no.6
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    • pp.17-26
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    • 2021
  • Ground investigation and result analysis generally used to examine all sorts of structures' subsidence or stability can be classified into sandy soil and cohesive soil, and analysis on the liquid limit of soil is utilized to evaluate the physical properties of ground and types or technical behavior of soil. The most widely used method to analyze liquid limit is Casagrande with which liquid limit can be calculated relatively easily; however, it is fairly difficult to apply it to soil equipped with intermediate properties. Therefore, concerning the properties of soil having the intermediate properties of sedimentary ground, this researcher mixed the clay from Yangsan, Gwangyang, and Busan with sandy soil to make intermediate soil and then carried out the test of consistency limit and also evaluated applicability by using the suggested formula of consistency revision. The sample of intermediate soil was the mixture of clay and sandy soil, and to produce intermediate soil, the content (Fc) of fine soil was applied as 50%, 75%, or 100%. Regarding the physical properties of intermediate soil, to maintain the properties of clay in the natural state, bentonite was added at a fixed rate for controlling the properties of clay, and then, consistency was analyzed. By adopting the formula of consistency revision suggested in advanced research, this author analyzed consistency based on the experiment and consistency based on the suggested formula of revision. Also, about intermediate soil collected at the site, consistency based on the experiment and consistency based on the suggested formula of revision were analyzed comparatively, and about intermediate soil collected, this researcher analyzed particle size and calculated the content (Fc) of fine soil to analyze intermediate soil in diverse conditions. Moreover, about intermediate soil collected at the site, the suggested formula of consistency revision was applied to calculate the compression index, and the compression index based on the experiment and the compression index based on the suggested formula were analyzed comparatively to evaluate the applicability of the suggested formula.

Effect of a combination of resistance and aerobic exercise training on angiogenesis-related protein expression in different type of skeletal muscle of aged rats (저항성 운동과 유산소 운동 훈련의 병행이 노화쥐 골격근 유형별 혈관신생 관련 단백질 발현에 미치는 영향)

  • Yeo, Hyo-Seong
    • Journal of the Korean Applied Science and Technology
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    • v.38 no.3
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    • pp.750-761
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    • 2021
  • This study was performed to observe the responses of angiogenesis-related protein expression in skeletal muscle of aged rats by regular resistance exercise training with aerobic exercise. For the purpose of the study, naturally aged SD rats (20-24 months, N=18) were used and divided into control (CON, n=6), resistance exercise (RE, n=6), and resistance + aerobic exercise (RE + AE, n=6) groups. RE group performed 3 sets × 4 exercises each session using a ladder for laboratory animals, and RE +AE group performed 2 sets × 3 times of ladder climbing and additional treadmill running (30 min) each session. After 8 weeks of exercise training, soleus muscle and extensor digitorum longus muscle (EDL) were extracted and used for analysis. Western blot was performed to analyze the expression levels of angiogenesis-related proteins (HIF-1α, VEGF, FLK-1, Ang-1, Ang-2) in skeletal muscle. As a result of the study, the expression of HIF-1α, VEGF, FLK-1, Ang-1, and Ang-2 proteins in soleus muscle (type I muscle) was higher in RE +AE than in CON group, and HIF-1α, VEGF, Ang-1, Ang-2 protein expression of RE group was higher than that of CON group. Furthermore, Ang-2 to Ang-1 ratio of RE + AE group was higher than that of RE group, showing differences by exercise type. In EDL muscle (type II muscle), HIF-1α was increased only by RE group, whereas VEGF and FLK-1 protein expressions were increased in both training types, and no difference was observed between the types of exercise training. In addition, there was no difference in angiopoieitin protein expressions in EDL muscle by exercise training. Therefore, in aging, regular exercise training induces skeletal muscle angiogenic response regardless of exercise type, and in particular, the combination of aerobic exercise with resistance exercise may have an additional positive effect on angiogenesis in type I muscle.

Isolation and Physicochemical Properties of Rice Starch from Rice Flour using Protease (단백질분해효소에 의한 쌀가루로부터 쌀전분의 분리 및 물리화학적 특성)

  • Kim, ReeJae;Oh, Jiwon;Kim, Hyun-Seok
    • Food Engineering Progress
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    • v.23 no.3
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    • pp.193-199
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    • 2019
  • This study aimed to investigate the impact of protease treatments on the yield of rice starch (RST) from frozen rice flours, and to compare the physicochemical properties of RST by alkaline steeping (control) and enzymatic isolation (E-RST) methods. Although the yield of E-RST, prepared according to conditions designed by the modified 23 complete factorial design, was lower than the control, the opposite trends were observed in its purity. E-RST (RST1, isolated for 8 h at 15℃ with 0.5% protease; RST2, isolated for 24 h at 15℃ with 1.5% protease; RST3, isolated for 24 h at 15℃ with 0.5% protease) with the yields above 50% were selected. Amylose contents did not significantly differ for the control and RST2. Relative to the control, solubilities were higher for all E-RST, but swelling power did not significantly differ for E-RST except for RST1. Although all E-RST revealed higher gelatinization temperatures than the control, the reversed trends were found in the gelatinization enthalpy. The pasting viscosities of all E-RST were lower than those of the control. Consequently, the enzymatic isolation method using protease would be a more time-saving and eco-friendly way of preparing RST than the alkaline steeping method, even though its characteristics are different.

A Comparison of the Effects between Eye-Mask and Light-Off Conditions on Psychiatric Patient Sleep (야간 조명 하 안대와 소등의 수면에 대한 효과 비교)

  • Shin, Juyong;Lim, Kyoung-Ok;Cho, Seongnam;Jang, Soyeong;Cha, Seung-Min;Han, Songyi;Kim, Moojin
    • Sleep Medicine and Psychophysiology
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    • v.28 no.1
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    • pp.27-33
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    • 2021
  • Objectives: The purpose of this study is to investigate the difference in the effects of eye-mask and light-off on sleep status according to a commercial fitness tracker and a sleep diary of psychiatric in-patients in correctional facilities where nocturnal light is compulsory. Methods: This study was conducted over 3 consecutive nights. In-patients of the National Forensic Psychiatric Hospital (n = 29) were assigned random subject numbers and slept as usual in the light-on condition on the first night. The subjects slept with eye-masks in the light-on condition on another night and without an eye-mask in the light-off condition on the other night. Subjects were asked to sleep wearing a commercial fitness tracker and to keep a sleep diary. The order of these changes in bedroom lighting condition on the second and third nights was assigned randomly to participants. Results: In comparison of the sleep variables between the light-on condition and the eye-mask condition, the Wakefullness After Sleep Onset (WASO) was shorter and sleep satisfaction was higher in the latter.(respectively, Z = 3.66, p < 0.017 ; Z = 2.69, p < 0.017) In comparison of the sleep variables between the light-on and light-off conditions, the WASO was shorter and sleep efficiency and sleep satisfaction were higher in the latter (respectively, Z = 2.40, p < 0.017 ; Z = 3.02, p < 0.017 ; Z = 3.88, p < 0.017). However, there were no differences in the sleep variables between the eye-mask condition and the light-off condition. Conclusion: Subjective improvements in sleep variables were noted in sleep diaries of institutionalized psychiatric patients under either the 'eye-mask' or 'light-off' condition. However, there were no significant differences between the 'eye-mask' and 'light-off' conditions. Therefore, we suggest that psychiatric patients in correctional facilities use eye-masks when sleeping.

Quality of Life and Characteristics of Depression with Subjective Cognitive Decline in Korean Adults : Data from the Seventh Korea National Health and Nutrition Examination Survey (한국 성인에서 주관적 인지저하를 동반한 우울증의 특성과 삶의 질 : 제 7기 국민건강영양조사를 중심으로)

  • Jeong, Jae-Hoon;Kim, Sung-Jin;Jung, Do-Un;Moon, Jung-Joon;Jeon, Dong-Wook;Kim, Yeon-Sue;Choi, Hyeon-Seok;Lee, Min-Joo;Jeon, Gyeong-Su
    • Korean Journal of Psychosomatic Medicine
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    • v.29 no.1
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    • pp.17-25
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    • 2021
  • Objectives : This study aimed to investigate quality of life, severity of depression, suicidality, subjective health and subjective stress of depression with subjective cognitive decline in Korean adults. Methods : We used the 7th KNHANES data to enroll 415 participants with a score of 10 or higher on Patient Health Questionnaire-9 (PHQ-9), aged 20-64. Depression was divided into two groups based on the presence/absence of subjective cognitive decline. Demographic and psychological characteristics were compared between two groups. Correlation analysis of subjective cognitive decline, quality of life, depression, suicidal idea was carried out. To detect which variables influenced quality of life, a multiple regression analysis was carried out. Results : Among the 415 participants, 98 had depression with subjective cognitive decline. We identified significant differences in age, marital status, education, employment between the two groups. After adjusting for these variables, depression with subjective cognitive decline had lower EuroQol-5D index scores, more severe depressive symptoms without cognition and worse subjective health than depression without cognitive decline. There was a significant correlation between subjective cognitive decline and quality of life (r=-0.236, p<0.001), suicidal idea (r=0.182, p<0.001), depression score without cognition (r=0.108, p=0.028). Through multiple regression analysis, subjective cognitive decline was predictor of reduced quality of life (β=-0.178, p<0.001). Conclusions : Depression with subjective cognitive decline has poor quality of life and severe depression. Cognitive decline should be considered to improve treatment result in depression.

Associations of Communication Skills, Self-Efficacy on Clinical Performance and Empathy in Trainee Doctors (전공의 의료커뮤니케이션 능력과 진료수행 자기효능감, 공감능력과의 상관관계)

  • Kim, Doehyung;Kim, Min-Jeong;Lee, Haeyoung;Kim, Hyunseuk;Kim, Youngmi;Lee, Sang-Shin
    • Korean Journal of Psychosomatic Medicine
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    • v.29 no.1
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    • pp.49-57
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    • 2021
  • Objectives : This study evaluated the medical communication skills of trainee doctors and analyzed the relationship between medical communication skills, self-efficacy on clinical performance (SECP) and empathy. Methods : A total of 106 trainee doctors from a university hospital participated. The questionnaire comprised self-evaluated medical communication skills, modified SECP and the Korean version of the Jefferson Scale of Empathy-Health Professionals version. The mean difference in medical communication skills scores according to gender, age, division (intern, internal medicine group or surgery group) and position (intern, first-/second- and third-/fourth-year residents) were analyzed. Pearson correlation coefficients were determined between medical communication skills, modified SECP and empathy. The effects of each variable on medical communication skills were verified using the structural equation model. Results : There were no statistically significant mean differences in self-evaluated medical communication skills according to gender, age, division or position. Medical communication skills had a significant positive correlation with modified SECP (r=0.782, p<0.001) and empathy (r=0.210, p=0.038). Empathy had a direct effect on modified SECP (β=0.30, p<0.01) and modified SECP had a direct effect on medical communication skills (β=0.80, p<0.001). Empathy indirectly influenced medical communication skills, mediating modified SECP (β=0.26, p<0.05). Conclusions : Medical communication skills are an important core curriculum of residency programs, as they have a direct correlation with SECP, which is needed for successful treatment. Moreover, the medical communication needs a new understanding that is out of empathy.