• Journal of the Korean Wood Science and Technology
• /
• 제17권1호
• /
• pp.22-54
• /
• 1989

Seasonal semi-greenhouse type solar-drying of 2.5cm-and 5.0cm-thick lumber of Quercus aliena Blume and Quercus variailis Blume was carried out to investigate the possibility of solar-drying of wood and to decide the active solar-drying period in Korea. In the active solar-drying period obtained solar-dehumidification, semi-greenhouse type solar-, air- and kiln-drying of 2.5cm -thick lumber of oaks were carried out to analyze drying-rates. -defects, and -yield in each drying-method and to calculate daily total absorbed solar-radiation the solar dryers. The energy balance equations were set up, considering all the energy requirements, to analyze the heat efficiencies of semi-greenhouse type solar and solar-dehumidification-dryer. In a seasonal drying the drying rate of semi-greenhouse type solar-dryer was highest in summer, and greater in fall, spring, and winter in order. Solar-drying time was 45% in summer to 50% in winter of the air-drying rime, and more serious drying-defects occurred in air-drying than in solar-drying. In the active solar-drying period. April, May, and June, the average drying rate in solar-dehumidification-drying was 1.0%/day and greater than 0.8%/day in semi-greenhouse type solar-drying. In solar-dehumidification-drying the time required to dry lumber to 10% moisture content was less than 60 days, and solar-dehumidification-drying showed the highest drying-yield, 65.01%, than the other drying methods. The daily total absorbed solar radiations were 8.51MJ on the roof collector and 6.22 MJ on the south wall collector. In the energy blance 69.48% of total energy input was lost by heat conduction through walls, roof. and floor 11.68% by heat leakage, 0.33% by heating the internal structures of the solar-dryer and 5.38% by air-venting. Therefore the heat efficiency of semi-greenhouse type solar-dryer 13.13%, was lower than that of solar-dehumidification-dryer, 14.04%. Solar-drying of lumber in Korea showed the possibility to reduce the air-drying-time in every season and the efficiency of solar-dehumidification drying was higher than that of semi-greenhouse type solar-drying.

• Journal of Trauma and Injury
• /
• 제22권2호
• /
• pp.254-259
• /
• 2009

Purpose: Pelvic trauma is a serious skeletal injury with high mortality. Especially in cases of severe injury trauma, treatment outcomes depend on early diagnosis and intervention. We expect trauma surgeon to play an important role in the management of severe multiple trauma patients. Methods: A retrospective study was performed on pelvic trauma patients with hemodynamic instability between March 2005 and September 2009. We divided the time period into period I (March 2005~Feburary 2009) and period II (March 2009~September 2009). The trauma surgeon and team started to work from period II. Data were collected regarding demographic characteristics, mechanism of injury, type of pelvic fracture, ISS(injury severity score), treatment modality, transfusion requirement, time to definitive treatment, and mortality. Results: During period I, among 7 hemodynamically unstable patients, 4(57.1%) patients died. However during Period II, only one of 6(16.6%) patients died. The demographic data and injury scores showed no differences between the two time periods, but the time to definitive treatment was very short with trauma team intervention(14.4 hrs vs. 3.9 hrs). Also, the amount of transfusion was less(41.1 U vs. 13.9 U). With arterial embolization, early pelvic external fixation led to less transfusion and made patients more stable. Conclusion: This study demonstrated the importance of the trauma surgeon and the trauma team in cases of hemodynamically unstable pelvic trauma. Even with the same facility and resources, an active trauma team approach can increase the survival of severely injured multiple trauma patients.

• 한국건설관리학회논문집
• /
• 제22권3호
• /
• pp.12-20
• /
• 2021

건설 품질 및 안전 확보, 비용분쟁 방지를 위해 최근, '적정 공사기간' 산정의 중요성이 부각되었다. 건축공사기간 산정기준 마련을 위해서는 상당량의 과거자료 분석이 필요하다. 그러나, 근로시간 단축, 품질규정 강화 및 기후조건 변화 등 건설사업 환경이 이미 변경되어 과거자료의 사용에 대해 많은 전문가들이 의문을 제기하고 있는 실정이다. 또한, 건축공사는 공사 여건에 따라 작업순서, 생산성 등이 매우 다양해 과거 통계치를 활용한 획일적인 공사기간 산정 시 오류 가능성이 상승한다. 따라서, 적극적인 '생각의 전환'을 통해 과거자료 분석 방식에서 현재생산자료 검토 방식으로 변경하는 새로운 해법을 본 연구를 통해 제시하였다. 즉, 설계단계에 '공정관리 전문가' 및 '공종별 시공전문가'를 투입하여, '적정 공사기간'을 검토·산정하는 절차를 제도화하였다.

• 한국비블리아학회지
• /
• 제35권2호
• /
• pp.85-108
• /
• 2024

본 연구는 최근 15년간의 연구데이터 관련 연구 현황을 파악하기 위하여 2010년부터 2024년까지의 연구데이터 학술논문의 연구 동향을 분석하고자 하였다. 목적을 달성하고자 Scopus DB에 게재된 학술논문 14,921편을 대상으로 키워드 빈도 분석 및 네트워크 중심성 분석을 수행하였다. 학술지 게재 시기에 따라 1기(2010-2014년), 2기(2015-2019년), 3기(2020-2024년)로 구분하여 UCINET을 활용한 키워드 네트워크 분석을 수행한 결과, 시기에 상관없이 연구되는 주요 키워드와 기간별로 주목받는 키워드, 시간이 지나면서 관심이 줄어드는 키워드를 도출하였다. 최근 15년간 연구데이터 관련 연구가 가장 활발히 이루어진 주제는 데이터 공유인 것으로 확인되었으며, 연결 중심성이 높은 키워드들이 대부분 매개 중심성 또한 높은 것으로 나타났다. 본 연구의 결과는 향후 국내 연구데이터 분야의 연구 방향성을 제시하는 기초자료로서 활용될 수 있을 것으로 판단된다.

• 대한치과교정학회지
• /
• 제17권2호
• /
• pp.223-248
• /
• 1987

The early tissue reactions in the periodontal tissues of the tension zones following the application of force (30gm) to the maxillary first molar teeth of the albino rats were studied by the light microscopy and electron microscopy The increase of periodontal fibroblasts was evident, particularly in 1 day survival period. Osteoblast differentiation and new bone formation on the alveolar bone surface were occurred from 1 day survival period. Mononuclear phagocytes occurred consistently and in relatively high number adjacent to and at some distance from blood vessel Extensive breakdown of collagen fibers was observed. The increase of the phagocytosis of collagen by the active fibroblasts was evident Also, collagen fibrils were sparse or lost near the macrophage.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제35권5호
• /
• pp.316-324
• /
• 2013

This case report describes the treatment of a 23-year-old woman who had lip protrusion with gummy smile and mentalis muscle strain. Orthognathic surgery was performed in conjunction with orthodontics. Minimum dental decompensation was performed with presurgical orthodontics followed by an anterior segmental osteotomy for the majority of dental decompensation. Counterclockwise rotation of the maxillomandibular complex was applied by LeFort I osteotomy, and bilateral sagittal split ramus osteotomies with anterior segmental osteotomy to achieve overall facial balance. The active treatment period was 15 months. Stable occlusion and skeletal relationship were observed after a 10-month follow-up period.

• Journal of Power Electronics
• /
• 제18권4호
• /
• pp.1007-1014
• /
• 2018

A novel dual DC-DC flyback converter with leakage-energy recycling is presented in this paper. Only an active switch is used for this converter. A pulse-width-modulation strategy is adopeted to control this switch. Two transformers are employed for the proposed converter. During the switch ON-period, the primary windings of the two transformers store energies. At the switch OFF-period, the energies stored in the primary windings of the two transformers are released to the output via the secondary windings of the two transformers. Meanwhile, the leakage energies of the two transformers can be recycled. The operating principles and steady-state analyses of the proposed converter are described in detail. A prototype circuit of the proposed converter is implemented for verifying the performances.

• Journal of Mechanical Science and Technology
• /
• 제15권6호
• /
• pp.764-775
• /
• 2001

Oscillartory thermocapillary flow of high Prandtl number fluids in the half-zone configuration is investigated. Based on experimental observations, one oscillation cycle consists of an active period where the surface flow is strong and the hot corner region is extended and a slow period where the opposite occurs. It is found that during oscillations the deformation of free surface plays an important role and a surface deformation parameter S correlates the experimental data well on the onset of oscillations. A scaling analysis is performed to analyze the basic steady flow in the parametric ranges of previous ground-based experiments and shows that the flow is viscous dominant and is mainly driven in the hot corner. The predicted scaling laws agree well with the numerical results. It is postulated that the oscillations are caused by a time lag between the surface and return flows. A deformation parameter S represents the response time of the return flow to the surface flow.

• 한국시뮬레이션학회:학술대회논문집
• /
• 한국시뮬레이션학회 2001년도 The Seoul International Simulation Conference
• /
• pp.72-76
• /
• 2001

Experimental design in simulation provides an efficient way of economizing simulation runs since a considerable number of simulation runs that originally were planned can be reduced by this approach. This experimental design method is an active area of research together with the output analysis and so no single panacea seems to exist so far. Thus, selection of techniques of experimental design and output analysis more lithely depends upon the objective of simulation analysis, budget constraint and sometimes the analysts subjective judgment. This paper attempts to describe an experimental design methodology for port investment analysis using a case study in a bulk terminal in Korea. Detailed display will be focused on simulation period, warm-up period, the number of replications needed in production runs after brief explanation on the system configuration.

• KDI Journal of Economic Policy
• /
• 제23권1_2호
• /
• pp.193-231
• /
• 2001

The purpose of this study is to clarify the real causes of gender wage differentials in Korea by analyzing changes over the period from 1984 to 1999. The participation rate of women in the Korean labor force has gradually increased since 1963, reaching 47.4 percent as of 1999. This increase can be attributed to more active participation by women of all ages, except those aged 15-19, as a result of their enrollment in higher level education. In particular, a remarkable rise in labor market participation was achieved by those aged 25-29. On the other hand, the ratio of female workers earnings to that of male workers has increased from 45.1 percent in 1972 to 63.1 percent in 1999. However, when the gender wage differentials are decomposed into various factors, it is found that discrimination components against female workers, compared to the skills or productivity characteristics, played a greater role for the 1994 to 1999 period.