• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.38 no.11
• /
• pp.913-921
• /
• 1989

This paper deals with a pole placement indirect adaptive control algorithm for discrete-time linear plants with arbitrary zeros. The resulting closed-loop control system is shown to be globally stable subject to the assumptions that an external input is persistently exciting and a lower bound on the magnitude of the Sylvester resultant of the plant numerator and denominator polynomials is known. The problem of controllability of the plant estimate in indirect adaptive control is handled by using an extended parameter correction. The validity of the proposed control algorithm is assured through simulation for a second-order plant.

• Journal of Mushroom
• /
• v.21 no.3
• /
• pp.118-125
• /
• 2023

We conducted an on-site application study at the livestock cooperative fertilizer plant to compare the composting period, temperature change, moisture content, and chemical properties between livestock manure compost using sawdust as a moisture regulator with those using spent oyster mushroom substrate. The composting period, moisture content, and fertilizer composition of compost containing spent oyster mushroom substrate did not differ from that of conventional compost mixed with sawdust after the first and second fermentation and post-maturation stages, it was suitable as a material for manufacturing livestock manure compost. The spent oyster mushroom substrate also lower the production cost of livestock manure compost by replacing the more expensive sawdust. The developed technology is expected to contribute towards the utilization of by-products of the oyster mushroom harvest while simultaneously producing high quality livestock manure compost.

• Journal of Preventive Medicine and Public Health
• /
• v.35 no.3
• /
• pp.245-254
• /
• 2002

Objective : To test if the intake of $H_2$ receptor antagonists ($H_2$-RAs) increases the risk of gastric cancer in the elderly. Methods : The source population for this study was drawn from the responders to a questionnaire survey administered to the Korea Elderly Pharmacoepidemiological Cohort (KEPEC), who were beneficiaries of the Korean Medical Insurance Corporation, were at least 65 years old, and residing in Busan in 1999. The information on $H_2$-RAs exposure was obtained from a drug prescription database compiled between inn. 1993 and Dec. 1994. The cases consisted of 76 gastric cancer patients, as confirmed from the KMIC claims data, the National Cancer Registry and the Busan Cancer Registry. The follow-up period was from Jan. 1993 to Dec. 1998. Cancer free controls were randomly selected by 1:4 individual matching, which took in to consideration the year of birth and gender. Information on confounders was collected by a mail questionnaire survey. The odds ratios, and their 95% confidence intervals, were calculated using a conditional logistic regression model. Results : After adjusting for a history of gastric ulcer symptoms, medication history, and body mass index, the adjusted OR (aOR) was 4.6 (95% CI=1.72-12.49). The odds ratio of long term use (more than 7 days) was 2.3 (95% CI=1.07-4.82). The odds ratio of short term use was 4.6 (95% CI=1.26-16.50). The odds ratio of parenteral use was 4.4 195% CI=1.16-17.05) and combination use between the oral and parenteral routes (aOR, 16.8; 95% CI=1.21-233.24) had the high risk of gastric cancer. The aOR of cimetidine was 1.7 (95% CI=1.04-2.95). The aOR of ranitidine was 2.0 (95% CI=1.21-3.40). The aOR of famotidine was 1.7 (95% CI=0.98-2.80). Conclusion : The intake of $H_2$-RAs might increase the risk of gastric cancer through achlorhydria in the elderly.

• Journal of the Korean BIBLIA Society for library and Information Science
• /
• v.34 no.4
• /
• pp.207-234
• /
• 2023

Since the advent of the Fourth Industrial Revolution, related studies have been conducted in various fields including industrial fields. In this study, to analyze domestic research trends on the Fourth Industrial Revolution, a keyword analysis and topic modeling analysis based on the LDA algorithm were conducted on 2,115 papers included in the KCI from January 2016 to August 2023. As a result of this study, first, the journals in which more than 30 academic papers related to the Fourth Industrial Revolution were published were digital convergence research, humanities society 21, e-business research, and learner-centered subject education research. Second, as a result of the topic modeling analysis, seven topics were selected: "human and artificial intelligence," "data and personal information management," "curriculum change and innovation," "corporate change and innovation," "education change and jobs," "culture and arts and content," and "information and corporate policies and responses." Third, common research topics related to the Fourth Industrial Revolution are "change in the curriculum," "human and artificial intelligence," and "culture arts and content," and common keywords include "company," "information," "protection," "smart," and "system." Fourth, in the first half of the research period (2016-2019), topics in the field of education appeared at the top, but in the second half (2020-2023), topics related to corporate, smart, digital, and service innovation appeared at the top. Fifth, research topics tended to become more specific or subdivided in the second half of the study. This trend is interpreted as a result of socioeconomic changes that occur as core technologies in the fourth industrial revolution are applied and utilized in various industrial fields after the corona pandemic. The results of this study are expected to provide useful information for identifying research trends in the field of the Fourth Industrial Revolution, establishing strategies, and subsequent research.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.18 no.2
• /
• pp.143-154
• /
• 2016

This study investigated the occurrences, causes, and mitigation of the recent ground subsidence and underground cavity generation events in Korea. Two main causes of ground subsidence are (1) the soil erosion by seepage during tunneling and earth excavation and (2) the damage of underground pipes. The main cause of the soil erosion during tunneling was the uncontrolled groundwater flow. Especially, when excavating soft grounds using a tunnel boring machine (TBM), the ground near TBM operation halt points were found to be the most vulnerable to failure. The damage of underground pipes was mainly caused by poor construction, material deterioration, and differential settlement in soft soils. The ground subsidence during tunneling and earth excavation can be managed by monitoring the outflow of groundwater and eroded soils in construction sites. It is expected that the ground subsidence by the underground pipe damage can be managed or mitigated by life cycle analysis and maintenance of the buried pipes, and by controlling the earth pressure distribution or increasing the bearing capacity at the upper ground of the buried pipes.

• Childhood Kidney Diseases
• /
• v.3 no.2
• /
• pp.161-169
• /
• 1999

Purpose : The urinary mass screening program for the detection of proteinuria in school aged population has been performed in Seoul since 1981. Systematic evaluation in corporation with the Seoul School Health Center for students with proteinuria identified in the mass screening has been performed from 1987. The results of urinary mass screening up to 1994 was reported. I report here the results of urinary mass screening from 1995 to 1997 and compare them with previous results and attempt to reveal the significance of urinary mass screening. Objects and Methods : In the 3-year period between 1995 and 1997, annually about 460,000 students comprising 3 different age groups; 5th grade of elementary school, 2nd grade of middle school and 2nd grade of high school were chosen, corresponding to the approximate ages of 11, 14, and 17 years, respectively. These subjects accounted for 26% of total school aged children in Seoul. The screening program was carried out in 3 steps. The 1st test was performed with dipstick at school and the 2nd at the Seoul School Health Center. Those students who showed proteinuria in the 1st and 2nd tests were referred to the hospital. Laboratory examinations including renal biopsies were performed to those students with pathologic proteinuria to clarify the incipient renal diseases. Results : 1) The prevalence of asymptomatic proteinuria was 0.28% in the 1st test. It peaked at the group of 14 years old as 0.34%, compared with 0.26% at the group of 11 years old and 0.24% at the group of 17 years old. It reached to 0.26% in male and 0.30% in female. 2) 25 percent of those having proteinuria at the first test were positive at the second test. 3) The proportion of patients with proteinuria by 3rd test were as follows; 25% of transient proteinuria, 55% of orthostatic proteinuria, 6% of constant proteinuria, 12% of proteinuria with hematuria, and 2% of transient proteinuria with isolated hematuria. Pathologic proteinuria were totaled as 20%. The prevalence of renal diseases among the age group of 7-18 years old was estimated to be 1.4 per 10,000. 4) Renal biopsy performed on 38 children with proteinuria at the third test revealed IgA nephropathy in 17(44%), focal segmental glomerusclerosis in 5(13%), minimal change disease in 4(11%), membranoproliferative glomeronephritis in 3(8%), $Henoch-Sch\"{o}nlein$ purpura nephritis in 3(8%), and others in 6(16%). Therefore, the prevalence of IgA nephropathy among the age group of 7-18 years old was estimated to be 0.64 per 10,000. 5) The prevalence of chronic renal failure was estimated to be 5.7 per 1 million of 7 to 18 years age group. Conclusions : 1) The prevalence of proteinuria in the first screening test was 0.28% and finally only 5% of them showed the pathologic proteinuria at the third test. 2) The prevalence of IgA nephropathy and chronic renal failure were 0.63 per 10,000 and 5.7 per 1 million, respectively among school-aged children in Seoul.

• Journal of the Korean Geographical Society
• /
• v.30 no.3
• /
• pp.230-241
• /
• 1995

The Characteristics of nocturnal temperature fields were analyzed to understand the factors of freezing-and-cold damages on orange orchards in Cheju Island. Temperatures were measured from January 7th through 27, 1995 at 25 sites in an area of 1x1.25$ extrm{km}^2$, Wasan-ri, Chochon-up, Pukcheju-kun located on the northeastern slope of Mt.Hanla. Several other weather elements such as wind and cloud were observed as supplementary data. Surface weather maps were also analyzed to clarify the influence of prevailing pressure patterns on the temperature fields. The vertical temperature profiles were obtained at the height from the ground up to 360 cm in 30 cm intervals at site 3, a frost hollow, and site 10 on the upper slope. The results show that freezing damages occured in the hollows, terrain depressions, rather than at the upper slope due to nocturnal radiation cooling as well as accumulation of cold airflow from Mt.Hanla. Windbreaks of densely planted Japanese ceders with stone-walls also roled as obstacles to the cold airflow in nights with Clear skies and light winds. The maximum intensity of temperature inversion in hollows, quasi-cold air lake, was 3.1$^{\circ}C$. Cold air from Mt.Hanla was trapped in the depressions up to a height of 90cm forming frost pocket. Man-made facilities such as shelterbelt or stone-wall which are built to prevent the penetration of cold north-westeries in winter aggravated the cold damage. The differance of daily minimum temperatures between before and behind shelterbelts was 2.$0^{\circ}C$. The man-made convection by smudgin which raised the temperatures up to 3.8$^{\circ}C$ can reduce the cold damage in the hellows.

• The Journal of the Convergence on Culture Technology
• /
• v.6 no.2
• /
• pp.481-487
• /
• 2020

In this study, finite element analysis was performed to evaluate the track irregularity of the existing track system on urban transit according to the large-scale excavation work that is constructed adjacent to the serviced line. Based on the numerical analysis, the effect of track irregularity generated during the step-by-step construction process was analytically derived, and the stability in terms of track deformation was evaluated through comparison with related standards. As the results, in the case of track irregularity items evaluated based on the relative displacement difference at a certain distance, such as alignment and vertical irregularity, it occurred most clearly at the location where deformation of the existing structure begins, such as the end point of adjacent excavation work. On the other hand, the overall vertical and horizontal displacement of the track was the largest deformation at the center of the construction section. The vulnerable position of the deformed side of the existing structure due to adjacent excavation is analytically proven that the both of the end point section and the center of the construction can be a vulnerable position in terms of track irregularity.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.221-221
• /
• 2023

기후변화에 관한 정부 간 협의체 6차 보고서에 따르면 강우 변동성이 증가함에 따라 홍수 피해가 빈번해질 것으로 예상된다. 집중호우, 태풍, 장마 등 물 관련 재해의 발생빈도와 규모가 댐의 홍수조절능력을 초과하는 경우 홍수량을 예측하고 댐 모의 운영을 통해 댐 방류량을 결정하기 어렵다. 그러므로 댐의 안정성 확보를 위해 기존의 댐 운영방식을 검토하고 개선하여 홍수조절용량을 확보하는 과정이 필요하다. 본 연구의 목적은 기존의 저수지 운영방식을 분석하고 극한의 홍수에 대비하여 저수지 운영 방식을 개선하는데 있다. 연구 대상 댐으로는 합천댐과 섬진강댐을 선정하였다. 합천댐과 섬진강댐은 홍수조절을 위해 Rigid ROM(일정률-일정량 방식)을 사용하고 있으며 200년 빈도 홍수량에 맞춰 설계되었다. 그러나 합천댐은 계획방류량(6,200 m³/sec)이 댐 하류지역의 설계홍수량(2,885 m³/sec)보다 2배 이상 크기 때문에 계획방류량만큼 방류하지 않더라도 하류에서 홍수피해가 발생하는 문제가 있다. 2020년, 섬진강댐은 200년 빈도의 홍수량보다 작은 홍수가 발생했음에도 불구하고 하류 지역에서 홍수 피해가 발생하였다. 본 연구에서는 우리나라에서 홍수기에 일반적으로 사용되는 저수지 운영 방식 - Auto ROM, Rigid ROM, Technical ROM -을 적용하여 댐의 안정성과 하류 홍수피해를 최소화하기 위한 최적의 운영 방안을 검토하였다. 200년 빈도 홍수량과 2020년 홍수 자료를 이용하고 저수지 운영 방식의 변경을 통해 홍수조절효과를 검토하였다. 또한, 홍수조절효과가 미약할 시 사전 방류를 통해 홍수조절효과를 향상시켰다. 본 연구는 안전하고 효율적인 댐 운영 방식을 분석함으로써, 타 다목적 댐 운영에 대한 참고자료로 활용될 수 있을 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.336-336
• /
• 2021

기후변화와 도시화로 인한 집중 호우와 불투수층 증가로 도시 홍수의 발생 빈도와 규모가 증가하고 있다. 인적, 물적 자원이 집중되어 있는 도시유역의 특성상 침수가 발생하면 이로 인한 직접적 피해 뿐만 아니라 사회경제적 2차 피해를 발생한다. 도시 홍수로 인한 피해를 줄이고 도시의 재해에 대한 회복력을 키우기 위해서는 관측과 더불어 정확한 모의 기술이 중요하다. 한편, 격자 기반 도시 홍수 모의는 집중 호우에 따른 침수의 시공간적 발생 양상을 물리적으로 해석하는 방법으로, 지표수-우수관거 이중배제 통합 모의, 수치기법, 병렬컴퓨팅, 수질 연계 모의 등의 측면에서 지금까지 많은 발전이 이루어져 왔다. 최근들어 원격탐사 기술의 발달로 공간해상도 1미터 수준 혹은 그 이상의 초고해상도 지형자료가 많은 지역에서 대해 가용해지고 있으며, 도시 홍수 해석에 이와 같은 초고해상도 자료를 적용하기 위한 연구가 활발히 진행되고 있다. 본 연구에서는 초고해상도 지형 및 토지 피복 자료의 공간해상도가 침수해석에 미치는 영향을 분석한다. 도시침수의 두가지 주요 요인인 내수침수와 외수범람 중에서 극한 강우에 의한 내수침수해석 사례만을 주요 연구 범위로 한다. 초고해상도 입력자료의 격자기반 도수 해석 모형으로는 운동파 기반의 2차원 지표 흐름 해석 모형을 적용하고, 초고해상도 모의의 효율적 계산을 위해 하이브리드 병렬 컴퓨팅 기술을 이용한다. 초고해상도 입력자료 적용 사례 대비, 공간해상도 저하에 따라 침수 면적이나 깊이 등에서 어떤 변화가 있는지 정량적으로 검토한다. 또한, 강우의 강도 및 공간분포가 초고해상도 도시 홍수 해석에 미치는 영향에 대해서 분석한다. 모의 결과로부터 도시 홍수 해석시 거리 단위(street-level) 정확도의 재현을 위해 적정한 공간해상도를 분석하고, 초고해상도 도시 홍수 모의를 이용한 기후변화에 따른 극한 홍수의 도시지역 영향 분석 및 회복력 개선 관련 연구의 가능성에 대해 논의한다.