한국의 FDI 동향 및 설명요인

학위논문(석사) -- 서울대학교대학원 : 국제대학원 국제학과(국제협력전공), 2023. 2. 이수형.This paper empirically studies the changing trends and examines how economic variables account for the changes in South Koreas outward FDI from 2001 to 2021. In the early 2000s, the major recipients were the USA, China, and Vietnam in the manufacturing industry. However, a shift in this trend is observed as more investments are now made in the Cayman Islands and Luxemburg in the finance and insurance industry. To confirm whether the differential patterns across the industries, investor sizes, and countries are due to the economic conditions, or specific time trends, we build a regression model that can control for such changes in economic conditions. Our findings suggest that the total trade value and GDP per capita are associated with outward FDI from South Korea. While the USA is still clearly one of the main recipients, investments made in Luxemburg and Cayman Islands are increasing at a rapid pace at 29.6% and 18.7% per annum respectively, which raises alarm on the importance of tax haven use.본 논문은 2001년부터 2021년까지 경제 변수가 한국의 해외직접투자 변화 추이에 미치는 영향에 관해 실증적 방법으로 연구하였다. 2000년대 초반에는 미국, 중국, 베트남의 제조업이 인기 투자 종목이었다. 그러나 최근 케이맨 제도, 룩셈부르크 등 국가의 금융·보험업계가 부상하면서 해외직접투자량이 증가세를 보였다. 산업별, 투자자 규모별, 국가별 차등 패턴이 경제 상황에 따른 효과인지, 혹은 특정 시계열 추세의 효과인지를 확인하기 위해, 경제 상황의 변화를 통제한 회귀 모델을 설계한다. 본 연구 결과는 총 무역량과 1인당 GDP가 한국의 해외직접투자와 관련이 있음을 시사한다. 2000년 이후 미국에 대한 투자율이 1위를 유지하고 있지만, 룩셈부르크와 케이맨 제도에 대한 투자율이 각각 연 29.6%, 18.7%로 빠르게 증가하는 새로운 추세가 관측되었다. 해당 국가들은 대표적은 조세피난처로 지목되고 있으므로 해당 투자의 적법성에 대한 조사가 필요할 것으로 보인다.1. Introduction 1 2. Literature review 2 3. Institutional background 4 4. Descriptive analysis 6 5. Regression analysis 7 6. Conclusion 13 References 15 Abstract in Korean 34석

모야모야병 환자에서 항인지질항체가 뇌졸중 발병에 미치는 영향: 후향적 코호트 연구

학위논문(석사)--서울대학교 대학원 :의과대학 의학과,2019. 8. 김정은.Purpose: To investigate the prevalence of antiphospholipid antibody (aPL) positivity and its clinical influence on the risk of cerebral diseases such as infarction or hemorrhage in patients with Moyamoya disease (MMD). Materials and methods: A total of 515 patients with MMD who had visited SNUH between January 2011 and May 2016 and checked the level of aPL (Anti-cardiolipin, anti-beta2-glycoprotein I and lupus anticoagulant) were included in this study. Proportion of patients with positive aPL antibodies in MMD was compared with that in 60 healthy controls. Clinical features at baseline and prevalence of cerebral events after baseline were analyzed according to the aPL positivity (aPL positive group vs. aPL negative group). Primary outcome in this study was the occurrence of cerebral hemorrhage or infarction (defined as the cerebrovascular event) in MMD patients during the follow-up, which was analyzed using Cox proportional hazard model. The mean (SD) follow-up period was 32.8 (47.5) months. There were no patients previously diagnosed as anti-phospholipid antibody syndrome or other autoimmune diseases. Results: At baseline, 39 (7.6%) patients showed positive result in at least one antiphospholipid antibody or lupus anticoagulant tests, which was comparable to that in the healthy controls (5%). In the patients with MMD, baseline features such as age, gender, smoking status and other co-morbidities such as hypertension, dyslipidemia and diabetes were comparable between the aPL positive group and the aPL negative group. During a total of 1914.5 person-year of observation, 63 cases of cerebral infarction occurred. In the univariate analysis, aPL positive group showed a significantly higher incidence of cerebral infarction (HR =2.30 95% CI =1.13 to 4.67). This result was consistent in the multivariable analysis where age, gender, hypertension and dyslipidemia were adjusted (HR=2.06 95% CI =1.01 to 4.19). No specific clinical factors including aPL group significantly influence the cerebral hemorrhage risk in the univariable analysis. Conclusions: The prevalence of aPL positivity was not different between the healthy control group and MMD patients group. However, positive aPL in MMD patients significantly increase the risk for future cerebral infarction.목적: 모야모야병 환자에서 항인지질 항체 양성률을 조사하고, 항인지질 항체 검사 양성여부가 뇌경색이나 뇌출혈과 같은 뇌졸중의 발생에 미치는 임상적 영향을 알아보고자 한다. 방법: 2011년 1월부터 2016년 5월까지 서울대병원에서 모야모야병을 진단 받은 2200명의 환자 중에 515명의 환자를 대상으로 항인지질 항체(항카디오리핀항체, 항베타2-당단백1항체, 루푸스항응고인자) 검사를 시행하였다. 모야모야병 환자의 항인지질 항체 양성률을 비교하기 위해 60명의 건강한 정상대조군과 비교하였다. 그리고 항인지질항체 양성인 환자군과, 항인지질항체 음성인 환자군의 임상적 특성을 분석하였다. 본 연구의 주된 결과는 연구기간 중 모야모야환자에서 뇌출혈이나 뇌경색이 발생하는 것으로 정의 하였고 그것을 Cox의 비례위험모형을 이용하여 위험인자를 분석하는 연구를 진행하였다. 모든 환자는 이전에 항인지질항체 증후군이나 다른 자가면역질환을 진단 받은 적이 없었고, 평균 추적관찰기간은 32.8개월(표준편차47.5)이었다. 결과: 모야모야병 환자에서 적어도 하나의 항인지질항체의 양성은 39명(7.6%)의 환자에서 관찰되었고, 이는 건강대조군(5%)에서의 항인지질 항체 양성률과 거의 차이가 없었다. 모야모야병 환자의 기본적인 임상적 특성에서 항인지질항체 양성군과 음성군 사이에 나이, 성별, 흡연여부, 이외에 고혈압, 고지혈증, 당뇨와 같은 동반질환의 유뮤는 각 그룹간에 차이는 없었다. 총 1914.5인년의 관찰기간동안, 63건의 뇌졸중이 일어났고, 단변량분석을 하였을 때, 항인지질항체 양성군에서 뇌졸중이 더 많은 빈도로 발생한 것을 알 수 있었다. (HR =2.30 95% CI =1.13 to 4.67)이 결과는 나이, 성별, 고혈압, 고지혈증등을 교정한 다변량 분석에서도 같은 결과를 보였다. (HR=2.06 95% CI =1.01 to 4.19) 관찰기간 동안 뇌출혈의 발생은 항인지질 항체 양성 여부와는 관련이 없었다. 결론: 모야모야 환자에서 항인지질항체 검사 양성을 보이는 경우 추후 뇌경색을 일으킬 가능성이 높다.Contents Abstract ························································································i List of figures ················································································iv List of tables ·················································································v List of abbreviations ·······································································vi Introduction ··················································································1 Methods ······················································································3 Results ························································································7 Discussion ················································································· 11 Conclusion················································································· 15 References ·················································································25 국 문 초 록··················································································29Maste

Analysis of the Non-diagnostic Results after Stereotactic Biopsy

Objective: Although stereotactic brain biopsy has played an important role in the diagnosis and management of brain lesions, there is a significant number of patients in whom a histologic diagnosis is not achieved. The non-diagnostic result of stereotactic biopsy poses a management dilemma. The goal of this study was to analyze the non-diagnostic results after stereotactic biopsy, subsequent management, progress and final diagnosis. Methods: The authors reviewed the clinical and radiological records of 158 patients who underwent stereotactic brain biopsies using Leksell stereotactic frame. We included 138 patients who were followed more than 6 months in this study. Results: The results were diagnostic in 118 cases and the overall diagnostic yield of the procedure was 85.6%. A definite histological diagnosis was not made in 20 patients: gliosis in 10, normal white matter in 5, necrosis in 2, infiltration of inflammatory cell in 2, and insufficient material in 1. The subsequent managements, progress and their final diagnoses were described. Conclusion: Stereotactic biopsy has evolved as a powerful and safe tool to provide tissue diagnoses with minimal disruption of normal functioning brain. Multiple serial biopsy, intraoperative histological diagnosis, and updated imaging-guided biopsy should be tried to minimize the sampling error. Clinical and radiological follow-up are essential for further diagnosis and management in non-diagnostic cases.ope

Three-Dimensional Printed Mesh-Cage Replacement for a Metastatic Spinal Tumor and a Vertebral Compression Fracture: A Report of Two Cases

Harms mesh cages are commonly used in the treatment of metastatic spinal tumors by spondylectomy with cage insertion and posterior screw fixation. These cages are even useful for the surgical reconstruction of spinal deformities with mesh-cage replacement after vertebral column resection (VCR). Mesh cages can be customized by 3-dimensional (3D) printing based on the angle between the endplates for the requisite weight-bearing capacity and fit. This study reports two cases wherein a 75-year-old man and a 63-year-old woman were treated with reconstructive spondylectomy and mesh-cage replacement, followed by posterior screw fixation. The 75-year-old man was initially diagnosed with an L4 metastatic non-small cell lung carcinoma accompanied by a pathologic fracture and severe paralysis. The 63-year-old woman had slipped 13 years before and sustained a T11-L1 compression fracture that was aggravated 6 months before this admission, with back pain and numbness in both soles. Herein, we describe the treatment approach with instrumentation using a customized 3D-printed mesh cage after total spondylectomy for the metastatic spinal tumor and after VCR for deformity repair surgery in the respective cases. Our application of a 3D-printed mesh cage in surgery for a metastatic tumor is the first report of such treatment in Korea. Although the use of customized 3D-printed cages for a metastatic spinal tumor and a severe compression fracture was effective, challenges remain regarding fitting, manufacturing time, and costs.ope

Developing a Quantifying Device for Soft Tissue Material Prop-Erties around Lumbar Spines

Knowing the material properties of the musculoskeletal soft tissue could be important to develop rehabilitation therapy and surgical procedures. However, there is a lack of devices and information on the viscoelastic properties of soft tissues around the lumbar spine. The goal of this study was to develop a portable quantifying device for providing strain and stress curves of muscles and ligaments around the lumbar spine at various stretching speeds. Each sample was conditioned and applied for 20 repeatable cyclic 5 mm stretch-and-relax trials in the direction and perpendicular direction of the fiber at 2, 3 and 5 mm/s. Our device successfully provided the stress and strain curve of the samples and our results showed that there were significant effects of speed on the young's modulus of the samples (p < 0.05). Compared to the expensive commercial device, our lower-cost device provided comparable stress and strain curves of the sample. Based on our device and findings, various sizes of samples can be measured and viscoelastic properties of the soft tissues can be obtained. Our portable device and approach can help to investigate young's modulus of musculoskeletal soft tissues conveniently, and can be a basis for developing a material testing device in a surgical room or various lab environments.ope

Late-Developing Metastatic Malignant Melanoma in the Thoracic Spine Originating from Choroidal Melanoma.

A 54-year-old woman visited Gangnam Severance Hospital for left side flank pain. She had a history of total removal of malignant melanoma on the left eye ball 20 years prior. No evaluation had been performed since then. A paravertebral mass at thoracic ninth level (T9) was discovered on spinal magnetic resonance imaging, and pathology confirmed malignant melanoma. Following positron emission tomography-computed tomography, no other metastasis was discovered. After removal of the paravertebral mass, palliative chemotherapy (dacabarzine + tamoxifene) was administered in 3 cycles over 2 months. Radiotherapy with simultaneous integrated boost technique was performed at 4,350 cGy total over 15 days, 290 cGy per delivery, and was administered with the first cycle of palliative chemotherapy. Despite this treatment, multiple metastases developed throughout her body 7 months later, and the patient is continuing chemotherapy.ope

Prevalence of Neuropathic Pain in Patients Scheduled for Lumbar Spine Surgery: Nationwide, Multicenter, Prospective Study.

BACKGROUND: There is limited evidence about surgical outcomes after lumbar spinal surgery in patients with neuropathic pain (NP) or the prevalence of NP proportions among patients with degenerative lumbar diseases who are candidates for a surgical interventions. OBJECTIVE: The objectives of this study were to investigate the prevalence of NP among patients scheduled for lumbar spinal surgery and the relationship between health-related quality of life (HRQoL) and NP. This study also aimed to identify the risk factors related to NP and compare the clinical outcomes after surgical treatment between patients with and without NP. STUDY DESIGN: This study was a nationwide, multicenter, prospective, and observational study. It was conducted from Sep-Oct 2011 to May 2013, and included a total of 1,109 patients who were scheduled for lumbar spinal surgery from 44 spinal centers (both orthopedics and neurosurgeons). SETTING: Multicenter study METHODS: Patients were diagnosed of having NP if the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) pain scale was = 12 points. The patients were investigated to assess the differences in their clinical outcomes one week and 3 months after surgery and were followed-up with regards to pain and HRQoL to explore the risk factors affecting NP. RESULTS: Of 1,109 recruited patients, 404 (36.4%) suffered from NP (mean age 62.06 years; 37.9% men) with mean LANSS score of 17.44 ± 4.06, while 705 (63.6%) had nociceptive pain with mean LANSS score of 6.03 ± 3.52. At baseline, patients with NP showed lower HRQoL and more severe pain compared to nociceptive pain patients. However, 3 months after surgical treatment, the NP group showed greater improvement in pain NRS (P = 0.087) and EQ-5D (P = 0.029) as compared to nociceptive pain group. Longer symptom duration was identified as a risk factor for NP (OR 1.003, respectively, P = 0.020). CONCLUSION: There was a high prevalence of NP in Korean patients scheduled for lumbar spine surgery, and these patients suffered greater pain and lower HRQoL than nociceptive pain patients. The more remarkable improvement NP patients showed after treatment highlights the importance of appropriate diagnosis and treatment of NP.ope

Does Graft Position Affect Subsidence After Anterior Cervical Discectomy and Fusion?

Study design: Retrospective cohort study. Objective: Implant subsidence is an important prognostic factor after anterior cervical discectomy and fusion (ACDF). Our purpose in this study was to investigate whether graft position affects subsidence after ACDF and to determine if there is a difference in clinical results based on allograft subsidence and position. Methods: We reviewed 92 patients who underwent single-level ACDF with allograft and plate between January 2012 and October 2018. Treatment levels were divided based on allograft position within 2 mm of the posterior margin of the augmented plate (Anterior group) or at greater than 2 mm (Center group). Subsidence was defined as segmental vertebral body height decrease of 2 mm or more at 1 year compared to 1 week after surgery. Results: Overall subsidence prevalence was 15 (16%) cases. Subsidence was 11% in the Anterior group (8/73) and 39% in the Center group (7/19; P = .012). The subsidence group showed smaller graft footprint size (graft/endplate ratio) compared with the nonsubsidence group, and pseudarthrosis occurred frequently in the subsidence. There was no significant difference in clinical results according to graft position. These findings indicate that anterior graft position reduces risk of subsidence (95% confidence interval = 0.085-0.949). Conclusion: To minimize risk of subsidence, the graft should be positioned on the anterior position of the surgical-level endplate. In addition, using a graft appropriate for endplate size will further reduce subsidence.ope

Feasibility of Using the Epidural Space Detecting Device (EPI-Detection TM) for Interlaminar Cervical Epidural Injection

Cervical epidural injection (CEI), which is widely used for the treatment of cervical radiculopathy, sometimes has been associated with post-operative complications. Recently, EPI-DetectionTM, which detects the negative pressure of the epidural space and notifies the proceduralist by flashing a light and producing a beeping sound, was introduced. We assumed that the newly developed device could be as safe and efficient as the conventional loss of resistance (LOR) method. Therefore, we aimed to evaluate the effectiveness of the EPI-DetectionTM and compare it to that of the conventional LOR method. We randomly assigned 57 patients to the LOR and EPI-Detection groups (29 and 28 patients, respectively). Subjects were treated with interlaminar CEI (ILCEI) using one of two methods. The measured parameters, i.e., operation time and radiation dose were lower in the EPI-DetectionTM group (4.6 ± 1.2 min vs. 6.9 ± 2.1 min; and 223.2 ± 206.7 mGy·cm2 vs. 380.3 ± 340.9 mGy·cm2, respectively; all p < 0.05) than in the LOR group. There were no complications noted in either group. Both the EPI-DetectionTM and LOR methods were safe and effective in detecting the epidural space, but the former was superior to the latter in terms of operation time and radiation exposure. The EPI-DetectionTM may help perform ILCEI safely.ope

Influence of Frailty on Life Expectancy in Octogenarians After Lumbar Spine Surgery

Objective: Many studies have reported positive surgical outcomes and decreased mortality after spine surgery in the elderly population, including patients between 85 and 90 years of age. Here, in addition to patient age, we investigated the influence of frailty on short and long-term mortality in octogenarians after lumbar surgery. Methods: We performed a retrospective analysis of 162 patients over 80 years of age who underwent posterior lumbar fusion or decompressive laminectomy between January 2011 and September 2016. We examined patient survival and modified frailty index (mFI) from medical records. Results: By October 2019, 29 of 162 patients had expired (follow-up period: 1-105 months). Three-month mortality was 1.9%, and 1-year mortality was 4.9%. Frailty did not affect long-term survival at 1 year but was associated with 3-month mortality (p = 0.024). Conclusion: There was no relationship in long-term survival according to frailty in patients 80 years of age or older, but a difference was identified in short-term mortality. When making a surgical decision for lumbar spine surgery in frail patients over 80 years of age, surgeons should pay attention to the short-term prognosis.ope