우리나라 출산율 저하의 원인과 그 대책

임국환(KookHwan Rhim),최만규(ManKyu Choi) 고려대학교 보건과학연구소 2005 보건과학논집 Vol.31 No.2

  A rapid and persistent decline of the birth rate in Korea began to occur in the early 1960s when the government enforced a five-year plan for economic development and a birth control policy for the declining rate. Recently, as a result, the total birth rate has declined to 1.19 which is the lowest level in the world according to the National Statistical Office. Fertility decline foreshadows serious social problems and a decrease in the national economic development such as the decline of economic activity population, the increase of the duty of supporting an aging population.<BR>  The aim of this study is first to examine the present situation and problems related to low fertility, and then to inquire into and discover the factors affecting the birth rate by comparing data from the 1970s to the recent trend of Korea"s precipitous drop in the birth rate.<BR>  As for the cause of the fertility decline, this study examined the marriage and delivery age of women, the divorce rate, and the birth sex ratio as a demographic factors, and GNI(gross national income), the proportion of women"s economic activity, the expense of bringing up children as a socio-economic factors. This study also analyzed the correlation between the birth rate and the relevant factors as the previous stage of the multiple regression analysis to discover the affects on the birth rate. As a result, the correlation among relevant factors, independent variables, was very high. So the stepwise multiple regression analysis(applied a reduced regression model) was performed to find out factors affecting the contin??uously decreasing the birth rate. As a result, the marriage age of women proved a negative factor affecting, statistically and significantly, the contin??uously decreasing total fertility in Korea. After all, a government supported policy and social circumstance are required to decrease women"s marriage age.

독서, 연민과 자기 이해의 여정

이국환(Lee, Kookhwan) 國際言語文學會 2013 國際言語文學 Vol.- No.28

터널의 변위측정을 이용한 지반정수 인식방법에 관한 연구

조국환 서울産業大學校 2005 논문집 Vol.54 No.2

터널과 같은 지하구조물의 설계 및 시공시 지반성질을 정확히 파악하는 것은 시공의 안정성 및 경제성을 위해 매우 중요하다. 그러나 지반의 상태를 대표하는 지반정수를 설계단계에서 파악하는 것은 거의 불가능하므로 일반적으로 시공시 현장계측을 수행하여 설계시 초기 입력한 지반정수를 보정하고 이 결과를 차후 시공에 반영하고 있다 (이인모 등 2005a). 현재까지 계측된 내공변위를 이용한 대부분의 역해석 방법은 절대변위를 이용하므로 계측시작 이전에 발생되는 초기변위의 예측이 필요하며 이 과정에서 필연적으로 불확실성을 갖게 된다 (김문겸 등 1995a; 김문겸 등 1995b; 이인모 등 1996; 이인모 등 1997). 이러한 불확실성을 피하기 위해 이인모 등(2005a)은 상대변위 만을 이용한 역해석기법을 제안한 바 있다. 본 연구에서는 터널주변 지반의 지반정수와 터널의 상대변위의 민감도 관계를 통하여 지반의 상태를 역해석할 수 있는 간략한 기법을 제안하였다. 연구에 사용된 민감도 기법은 Stubbs와 Osegueda(1990)에 의해 제안된 바 있는 시스템인식기법을 응용하였으나, Stubbs와 Osegueda의 시스템인식기법은 매개변수와 고유진동수의 민감도 관계를 기초로 하므로 정적인 상대변위를 적용할 수 있도록 관계식을 재유도하였다. 본 연구에서 제안된 기법의 적용성은 3차원 터널 구조물 수치예제를 통하여 검증하였다. In designing underground structure such as tunnels, estimating geotechnical characteristics of the ground is one of the most important and difficult tasks. In this paper, a methodology that can identify geotechnical parameters using only field-measured relative convergence displacements is presented. By using only relative convergence measurement data, inevitable errors in absolute convergence estimation can be avoided and in turn the parameter estimation process can be simplified. The methodology utilizes sensitivity relationship between static displacement measurements and geotechnical parameters. The feasibility and applicability of the proposed methodology is verified via a 3-d numerical example of a tunnel structure.

정신적 장애인의 건강수준과 노동시장 차별경험이 경제활동에 미치는 요인분석

박효은 ( Hyoeun Park ),임국환 ( Kookhwan Rhim ),최만규 ( Mankyu Choi ) 대한보건협회 2015 대한보건연구 Vol.41 No.2

Objective: The aim of the study was to analyze some factors determining economic activities of mentally ill people : First, the factors associated with sociology of population, health resources, and discrimination on labor``s market. Further, the research was to suggest practical and policy implications for boosting economic activities by people with mental disorders. Methods: The data were based on the 4th Panel Survey of Employment for the Disabled(2011) by Korea Employment Agency for the Disabled, including 346 mentally incapacitated people of a total of 5,092 subjects in the study. Logistic regression analysis was performed to examine the factors influencing employment status and those determined by type of disability. Results: The result of the study is as follows. Of 346 subjects of analysis, 64(18.2%) were economically active population, and 284(81.8%), not. In an integrated model, one of the most influencing factors for economic activities was experienced discrimination in job-seeking and employment. Additionally, it showed some favoring factors in economic activities for : those residing in medium-sized cities, those with larger households, those married, those in ``subjectively`` good health, and those independent of daily lives`` assistance. Conclusion: According to our analysis, through these results, some suggestions should be made as follows : Against the backdrop, business owners and colleagues should achieve a better understanding of people with psychological disorders and should take practical action against ``adverse selection`` for them. The government should implement policies to promote active employment of the mentally incapacitated and to support business owners with practical assistance.

Impact of Crohn’s Disease on the Survival of Patients with Small-Bowel Adenocarcinoma in Korea: A Bicenter Cohort Study

Kim Kyuwon,Choi Kookhwan,Hwang Sung Wook,Im Jong Pil,Ye Byong Duk,Kim Joo Sung,Park Kyu Joo,Yang Suk-Kyun,Koh Seong-Joon,Park Sang Hyoung 거트앤리버 소화기연관학회협의회 2023 Gut and Liver Vol.17 No.4

Background/Aims: Owing to the low prevalence of small-bowel adenocarcinoma (SBA), data on the impact of Crohn’s disease (CD) on the survival of patients with SBA are lacking. Therefore, we investigated this issue in this study. Methods: In this bicenter cohort study, patients with histologically confirmed SBA were retrospectively enrolled and classified into two groups: sporadic SBA and CD-associated SBA. Patients with duodenal SBA were excluded. Overall survival, disease-free survival, and factors associated with survival were analyzed. Results: Of 128 patients with SBA, 115 had sporadic SBA and 13 had CD-associated SBA. Ileal involvement and poorly differentiated tumors were more common in the CD-associated SBA group than in the sporadic SBA group (ileal involvement, 53.8% vs 22.6%; poor differentiation, 46.2% vs 14.8%; both p<0.05). In survival analysis, overall survival showed no statistical difference between the sporadic SBA and CD-associated SBA groups (p=0.370). However, when stratified by stage, the adjusted overall survival of the CD-associated SBA group was lower in patients with an advanced disease stage (p=0.029). Disease-free survival showed the same tendency, albeit without clinical significance (p=0.097). CD (hazard ratio [HR], 2.308; p=0.047), older age (≥65 yr) at SBA diagnosis (HR, 2.766; p=0.001), and stage III/IV disease (HR, 3.151; p<0.001) were factors associated with mortality. Conclusions: The overall survival of patients with CD-associated SBA did not differ from that of patients with sporadic SBA. However, as CD is an independent risk factor for mortality, vigilant surveillance in high-risk patients may be crucial.

超音波의 垂値探傷法에 의한 傾斜를 갖는 圓形 平面缺陷의 크기 評價에 관한 硏究

한응교,김기중,이국환 韓國非破壞檢査學會 1984 한국비파괴검사학회지 Vol.4 No.1

In the straight beam inspection of ultrasonic wave, the method for evaluating flaw size by AVG diagram is useful as a method for the quantitative evaluation of results of ultrasonic flaw detection. This study was carried out the measure the size of circular flat flaw with the inclination by straight beam inspection and could be decreased the error of application due to the inclination of flaw by AVG diagram in consideration of correction coefficient. From the result of the experiment, the error by means of the application of experimental values to AVG diagram was increased as the inclination angle grows. Also, it was increased the error of application as the detecting frequency and diameter of flaw grows in the same inclination angle. In case of diameter of flaw 6㎜, AVG diagram could be applied to the inclination angle 3˚ for 5 MHz, 7˚ for 2.25 MHz, 15˚ for 1 MHz in the range of 20% error and the theory was concided with the experiment to 5˚ for 5 MHz, 10˚ for 2.25 MHz, 15˚ for 1 MHz in the range of 10% error by correction eq. (45) due to the inclination angle. Therefore, it is considered that the results obtained from this study will be somewhat helpful informations for the size evaluation of circular flat flaw with the inclination.

The association between Alcohol Consumption Behavior and Mental Health in a Community in Seoul

Bohye Lee,Jinhee Kim,Mankyu Choi,Kookhwan Rhim 한국알코올과학회 2009 한국알코올과학회 학술대회 Vol.2009 No.1

상대변위를 이용한 지반정수 인식

최상현(Choi Sanghyun),조국환(Cho Kookhwan) 한국철도학회 2005 한국철도학회 학술발표대회논문집 Vol.- No.-

In designing underground structure such as tunnels, estimating geotechnical characteristics of the ground is one of the most important and difficult tasks. In this paper, a methodology that can identify geotechnical parameters using only field-measured relative convergence displacements is presented. By using only relative convergence measurement data, inevitable errors in absolute convergence estimation can be avoided and in turn the parameter estimation process can be simplified. The methodology utilizes sensitivity relationship between static displacement measurements and geotechnical parameters. The feasibility and applicability of the proposed methodology is verified via a 3-d numerical example of a tunnel structure.

LoRa, Sensor Node, Cloud Platform을 활용한 계측관리에 관한 연구

이강중(Lee, KangJung),김지환(Kim, JiHwan),하민수(Ha, MinSoo),조국환(Cho, KookHwan) 한국방재학회 2020 한국방재학회논문집 Vol.20 No.6

최근 4차 산업혁명으로 통신분야와 센서분야는 눈부시게 발전하고 있다. 그 중 LoRa LPWAN은 저전력 IoT 전용기술로기존의 LTE 망보다 저렴하며, 근거리 통신방식(Bluetooth/WiFi/Zigbee)보다 넓은 커버리지를 제공하는 통신기술이다. 이번연구에서 LoRa LPWAN 통신을 활용한 계측관리 시스템을 제안하였다. 지상구간과 지하구간에 각각 공용망(Public), 자가망(Private)을 활용한 하이브리드 계측시스템으로 구축하였다. 각 메카니즘에 맞는 센서를 선정하여 고유신호를 처리할 수 있는센서노드를 개발하였으며, 원시 데이터를 Cloud Platform에 저장할 수 있는 통합 모니터링 프로그램을 개발하였다. 연구결과 통신 성공률은 1차 송수신시 90%, 2차 송수신시 99%로 나타났으며, 센서에서의 측정치와 센서노드 연결 후 통신 완료시측정치가 정확히 일치하는 것으로 확인되었다. With the recent Fourth Industrial Revolution, communication and sensor fields are developing remarkably. Among them, LoRa low-power wide-area network (LPWAN) uses low-power Internet-of-things-only technology, which is cheaper than the existing long-term evolution network, and it is a communication technology that provides wider coverage than short-range communication methods (such as Bluetooth, WiFi, and Zigbee). In this study, a measurement management system was developed using LoRa LPWAN communication. It was constructed as a hybrid measurement system using public and private networks for the ground and underground sections, respectively. We developed a sensor node that could process unique signals by selecting sensors suitable for each mechanism and an integrated monitoring program that could store raw data in the Cloud Platform. The results showed that the communication success rate was 90% for the first transmission and reception and 99% for the second transmission and reception. It was confirmed that the measured values at the sensor and when communication was completed after connecting the sensor node were equal.

TBM터널 궤도하부 채움재와 궤도진동과의 상관관계 분석

박성범(Park, SungBum),이세희(Lee, SeHee),김지환(Kim, JiHwan),조국환(Cho, KookHwan) 한국방재학회 2019 한국방재학회논문집 Vol.19 No.7

최근 철도의 고속화로 인하여 선형의 직선화가 요구되고 도심지를 통과하는 철도망이 증가함에 따라 TBM터널 시공이 증가하고 있다. 철도터널에 TBM공법 적용시 기계의 원형헤드특성상 불가피하게 깊은 깊이의 궤도하부 채움구간이 발생하지만 이 구간의 채움방안에 대한 연구 및 설계기준은 현재 미흡한 실정이다. 또한 비용절감을 위해 콘크리트와 유사한 재료로 채움을 시행하고 있으나 채움구간을 불연속체로 시공할 경우 열차통과시 발생하는 진동의 전파에 영향이 발생할 수 있으므로 반드시 채움재료별 동적거동 분석을 수행하여 적절한 채움방안으로 시공하여야 한다. 본 논문에서는 시멘트 함유량 7~13%의 입도조정쇄석을 채움재료로 선정하고 각 재료의 동적물성치를 파악하고자 실내실험을 수행하였다. 또한 실내실험에서 얻어진 동적물성치를 수치해석에 적용하여 열차진동에 의한 채움구간의 동적거동을 분석하였다. 수치해석결과, 임계속도에서 공진현상이 발생하며, 일정 시멘트 함유량 이하일 경우 높은 진동가속도로 인해 채움구간의 불안정한 동적거동이 일어나므로 적절한 채움방안이 적용되어야 할 것으로 나타났다. Due to the high speed of railway and the railway network passing through an urban area, the construction of tunnel using tunnel boring machine (TBM) has been increasing. During TBM tunneling, a deep filling section, about 3 m in depth, under the slab track is formed by the circular machine head. The research and the design standards for filling this section are currently insufficient. In addition, when the section is filled with lean concrete, it may negatively affect the propagation of train vibration. Therefore, it is necessary to analyze the dynamic behavior of filling materials and follow a suitable filling method. In this study, laboratory tests were conducted to determine the dynamic properties of bottom filling materials. Granular crushed stone with a cement content of 7-13% was selected as the filling material. Numerical analyses that reflect the results of the laboratory tests were also performed to analyze the dynamic behavior of the filling section under slab track. The results of these analyses showed that resonance occurred in the filling section depending on the critical and subcritical speeds of the vehicle.