成長經濟學의 系譜 (其 1)

Chung-Hyo Lee(李忠孝) 서울대학교 경제연구소 1965 經濟論集 Vol.4 No.4

1. Since Harrod published An Essay in Dynamic Theory in 1939, studies on economic growth by model approach have been proceeded with accelerating impetus in both views of theoretical ramification, mathematical complications and bibliographical quanta. In consequence, it comes to be almost forbidden to survey the whole ganut of theories of the subject and find a family pedigree among them, as J. R. Hicks concedes. In this paper, none the less, it is tried to make a bird's-eye views of the theories, by confining it in Part I to models of one-good economy. 2. I understood that Harrod's warranted growth rate of income is an equilibrium steady-state growth rate if warranted rate is equal to or less than natural rate of growth of income. And the warranted rate is understood as the rate satisfying entrepreneurs in their current pursuit of business and at the same time as the rate of capital stock which meet at all times just that amount of capital required for current production; the natural rate understood as being equivalent to the rate of growth of labour force which is fixed by noneconomic demographic forces. 3. Steady-state growth is approached from two sides, labour and capital in turn. Firstly, unemployment equilibrium models are considered. Closest to static Keynesian theory, models of this class are predicated upon the assumption that the presence of unemployment, even of continuously increasing amounts of unemployment, is not incompatible with equilibrium. Secondly, the neoclassical models assuming flexibility in capital-output ratio are reviewed. In the neoclassical approaches, investment equal to full-employment savings is assumed a requirement for there to be equilibrium, while the amount of labour and capital required to produce a unit of output is assumed not to be fixed. Such assumptions of neo-classical approaches, rendering a derivation of Harrod's prototype, reflect historical observations of co-temporaneous different techniques in production and nearly full-employment trend in the capitalist economies, though the trend having been interrupted sporadically due to somewhat "sinusoidal" features of the capitalist systems. Main proponents of the approaches are Meade, Solow, Swan and Samuelson. Their basic conclusion is that, when production takes place under the usual neoclassical conditions of variable proportions and constant returns to scale, (i.e., under the neo-classical type of linear homogeneous production function) no simple opposition between natural and warranted rates of growth is possible. There may not be any knife-edge which in fact in the case of the Cobb-Douglas function there never can be. The system of model economy can adjust to any given rate of growth of the labour force and eventually approach a state of steady-state equilibrium growth path. 4. In lieu of varying capital-output ratio, the. possibility of variable saving-income ratio can be considered. Such approaches may be called Keynesian on classical, the latter nomenclature being adopted in the paper because they seem to mean ultimately zero-saving by wage-earners as in the Ricardian antecedents. In this class of approaches the hypothesis is laid down that the savings both of profit-earners and of wage-earners are a function of their incomes, but that profit-earner's propensity to save is higher than that of wage-earners, so that the overall saving-income ratio depends on the distribution of income. The classical models, however, usually combine such hypothesis with varying proportions of capital and labour to seek steady-state equilibrium. 5. Another approach is to consider the possibility of varying the rate of growth of population, so that the adjustment needed to achieve steady-state equilibrium can take place on the side of the natural rate instead of on the side of the warranted rate. In this case the population is a function of the level of real wage less the subsistence wage and a direct relationship is established betw

비고용 V-Cu계 MA합금의 중성자 및 X선 회절에 의한 상분석

이충효,조재문,이상진,김지순,Lee Chung-Hyo,Cho Jae-Moon,Lee Sang-Jin,Kim Ji-Soon 한국재료학회 2004 한국재료학회지 Vol.14 No.5

The mechanical alloying (MA) effect in immiscible V-Cu system with positive heat of mixing was studied by not only the neutron and X-ray diffraction but also the analysis of DSC spectra. The total energy, ΔHt accumulated during MA for the mixture of $V_{50}$ $Cu_{50}$ / powders increased with milling time and approached the saturation value of 14 kJ/mol after 120 h of milling. It can be seen that the free energy difference between the amorphous phase and the pure V and Cu powders with an atomic ratio 5:5 is estimated to be 11 kJ/mol by Miedema et al. This is thermodynamically taken as one of the evidences for the amorphization. The structural changes of V-Cu MA powders were characterized by the X-ray diffraction and neutron diffraction. We take a full advantage of a negligibly small scattering length of the V atom in the neutron diffraction measurement. The neutron diffraction data definitely indicate that the amorphization proceeds gradually but incompletely even after 120 h of MA and bcc-Cu Bragg peaks appears after 60 h of MA.

기계적 합금화에 의한 Mg-Si계 열전화합물의 합성 및 평가

이충효,Lee, Chung-Hyo 한국결정성장학회 2007 韓國結晶成長學會誌 Vol.17 No.3

본 연구에서는 나노결정립의 $Mg_2Si$ 열전화합물을 제조하기 위하여 기계적 합금화(MA)를 적용하였다. 단상의 초미세 $Mg_2Si$ 열전화합물을 얻기 위하여 최적 볼밀조건 및 열처리 조건을 X선 회절분석과 시차주사 열량분석을 이용하여 조사하였다. $Mg_{66.7}Si_{33.3}$ 혼합분말을 $20{\sim}180$시간까지 볼밀 처리한 경우 모든 시료에서 $220^{\circ}C$ 및 $570^{\circ}C$ 근방에 broad한 발열 반응이 관찰되었다. 한편 $Mg_{66.7}Si_{33.3}$ 혼합분말을 260시간 동안 볼밀 처리한 경우 $230^{\circ}C$에 예리한 발열피크를 보였다. 단상의 $Mg_2Si$ 화합물은 $Mg_{66.7}Si_{33.3}$ 혼합분말을 60시간 동안 MA처리 후 $620^{\circ}C$까지 열처리함으로써 얻을 수 있었다. MA분말시료의 치밀화는 50MPa, $800{\sim}900^{\circ}C$에서 흑연다이를 사용하여 SPS 소결을 실시하였다. Mg-Si계 MA 분말시료의 SPS 소결시 수축은 $200^{\circ}C$ 근방에서 현저하게 관찰되었다. SPS법으로 고화된 성형체의 밀도측정 결과, 모든 시료에서 이론밀도의 94% 이상 금속광택을 나타내는 치밀한 소결체임을 알 수 있었다. We have applied mechanical alloying (MA) to get $Mg_2Si$ thermoelectric material with nano-sized grains. An optimal milling and heat treatment conditions to obtain the single phase of $Mg_2Si$ compound with fine microstructure were investigated by X-ray diffraction and differential scanning calorimetry (DSC) measurement. The $Mg_{66.7}Si_{33.3}$ MA samples ball-milled for $20{\sim}180\;hrs$ exhibit two broad exothermic heat releases around $220^{\circ}C$ and $570^{\circ}C$. On the other hand, MA sample ball-milled far 260 hrs exhibits only a sharp exothermic peak at $230^{\circ}C$ Single phase Mg2Si powder can be obtained by MA of $Mg_{66.7}Si_{33.3}$ mixture for 60 hours and subsequently heated up to $620^{\circ}C$. Sintering of the MA powders was performed in a spark plasma sintering (SPS) machine using graphite dies at $800{\sim}900^{\circ}C$ under 50 MPa. The shrinkage of sintering sample during SPS was significant at about $200^{\circ}C$. All compact bodies have a high relative density above 94% with metallic glare on the surface.

기계적합금화법에 의한 연자성 복합분말의 제조 및 구조관찰

이충효,Lee, Chung-Hyo 한국재료학회 2019 한국재료학회지 Vol.29 No.4

Fabrication of soft magnetic composite powders for the $Fe_2O_3-Ca$ system by mechanical alloying(MA) has been investigated at room temperature. It is found that soft magnetic composite powders in which CaO is dispersed in ${\alpha}-Fe$ matrix are obtained by MA of $Fe_2O_3$ with Ca for 5 hours. Changes in magnetization and coercivity also reflect the details of the solidstate reduction process of hematite by pure metal of Ca during MA. The saturation magnetization of MA powders increases with increasing MA time and reaches a maximum value of 65 emu/g after 7 hours of MA. The average grain size of ${\alpha}-Fe$ in MA powders, estimated by diffraction line-width, gradually decreases with increasing MA time and reaches 52 nm after 5 hours of MA. It can also be seen that the coercivity of the 5-hour MA sample is fairly high at 190 Oe, suggesting that the grain refinement of already-produced ${\alpha}-Fe$ tends to clearly occur during MA.

MA법에 의한 V-Co계 비정질합금의 제조 및 구조분석

이충효,Lee, Chung-Hyo 한국결정성장학회 2012 한국결정성장학회지 Vol.22 No.1

본 연구에서는 출발원료로 ${\sigma}$-VCo 금속간화합물과 $V_{50}Co_{50}$ 혼합분말을 각각 사용하여 기계적 합금화에 따른 비정질화 가능성을 조사하였다. X선 회절에 의해 얻어진 전구조인자 S(Q) 및 동경분포함수 RDF(r)의 결과로부터 볼밀링이 진행됨에 따라 비정질상의 구조적 특징이 분명히 관찰되었다. 120시간 MA 처리에 의하여 두 경우 모두에서 비정질상이 생성됨을 알 수 있었다. 60시간 동안 MA 처리한 $V_{50}Co_{50}$ 분말시료의 열분석 에서는 약 $600^{\circ}C$에 비정질상의 결정화에 의한 발열 peak가 관찰되었다. X선 회절법에 의해 얻어진 전구조인자 및 동경분포함수의 분석으로부터 MA 시간에 따라 출발 결정상은 비정질상의 특징적인 원자구조로 서서히 변화함을 알 수 있었다. In the present study, we investigated the effect of mechanical alloying (MA) on the formation of amorphous VCo system through solid state reaction during ball milling. Two types of powder samples, ${\sigma}$-VCo intermetallic compound and $V_{50}Co_{50}$ powder mixture, were applied as a starting materials. With increasing milling time, a structural characteristics into the amorphous state is distinctly observed from the structural factor and radial distribution by X-ray diffraction. Amorphization has been observed in all two types of samples after the milling for 120 hrs. DSC spectrum of $V_{50}Co_{50}$ powder sample milled for 60 hrs indicates a sharp exothermic peak from the crystallization at $600^{\circ}C$. The structure factor, S(Q) and radial distribution function, RDF(r), observed by X-ray diffraction gradually change into a structure characteristic of an amorphous state with increasing MA time.

A Study of Industrialization

이충효 ( Chung Hyo Lee ) 한국경제학회 1962 經濟學硏究 Vol.10 No.1

논문 : 수도권 물류단지 경쟁력 평가를 통한 경인 아라뱃길 물류단지 개선과제

이충효 ( Choong Hyo Lee ),정태원 ( Tae Won Chung ) 한국해운물류학회(구 한국해운학회) 2011 해운물류연구 Vol.27 No.3

본 연구에서는 각 기업의 물류시설 담당자들을 대상으로 물류단지 입주고려 요인 중요도 조사, 현재 수도권내 조성중인 물류단지(특정업종 관련기업 유치가 예상되는 이천패션물류단지 제외한 6개 물류단지)에 대한 경쟁력 및 경인 아라뱃길 물류단지의 개선과제 우선순위를 도출함으로서 최근 공급되고 있는 물류시설별 기능 정립에 대한 필요성을 제시하였다. 물류단지 입주결정요인을 바탕으로 한 수도권내 조성중인 물류단지 중 경쟁력 우선순위로는 경인 아라뱃길 김포고촌물류단지가 1순위를 기록했다. 해당 물류단지의 개선과제로는 광역 및 대중교통 연계, 세제지원 확보, 입주업종 집적화 등의 순으로 우선순위가 도출되었다. This study examines the importance of factors regarding the moving in of the logistics complex with the subjects of those in charge of logistics facilities of each company. Also, this paper has drawn the order of priority of improvements for the GI WATERWAY logistics complex and competitiveness of logistics complexes beingpresently constructed in the capital area.Through that, this research suggests necessity to establish the functions of logistics complexes currently being supplied. From the order of priority of competitiveness based on the decisive factors of the moving in of logistics complexes, GI WATERWAY GIMPO GOCHON logistics complex ranked first. Regarding the improvements of the proper logistics complex, the order of priority was drawn as connecting metropolitan and public transportation, securing taxational support, and accumulating the types of business moving in, etc.

경인 아라뱃길 김포고촌물류단지 입지선택요인 중요도 분석에 관한 연구

이충효 ( Choong Hyo Lee ),정태원 ( Tae Won Chung ) 한국해운물류학회(구 한국해운학회) 2013 해운물류연구 Vol.29 No.2

본 연구는 공급자와 수요자간의 인식의 차이 발생이 물류단지 부문에서도 악영향을 미치고 있다는 가정에서 접근하였다. 김포고촌물류단지의 사례를 통해 향후 단지 개발 방향에 대해 시사점을 제시하기 위해 경인 아라뱃길 김포고촌물류단지 분양기업과 사업시행자인 한국수자원공사 단지계획ㆍ공사ㆍ분양담당자들을 대상으로 입지 선택요인의 상대적 중요도를 조사하였다. 주 기준 3가지 요인과, 세부기준 8가지 요인에 대해 계층을 구성하여 AHP 분석으로 중요도 우선순위를 도출 하였다. 분양기업의 경우 총체적 중요도 우선순위는 지구단위ㆍ토지이용계획, 인프라시설, 사업시행자, 정부 및 지자체 지원 순으로 나타났으며, 사업시행자의 총체적 중요도 우선순위는 자연환경, 인프라시설, 인문환경 순으로 도출되었는데, 공급자와 수요자간 인식의 차이가 발생되지 않도록 단지계획 수립시 고객의 니즈가 반영되어야 할 것이다. This study conducted research into the relative importance of the selection factors of a location aimed at companies who are going to move into the Gyeong-in Ara Waterway Gimpo Gochon Logistics Complex and persons in charge of the design, construction, and sales of the complex at the Korea Water Resources Corporation. The study withdrew priority in importance with an AHP technique by composing a hierarchy concerning three factors of the main criteria and eight factors of the detailed criteria. Then, the study proposed the application of the case of the Gimpo Gochon Logistics Complex and its analysis as well as a direction for future development of the complex. In the case of companies moving into the complex, the priority in total importance was discovered to be in this order: zone unit/land use plan, infrastructure, business operator, and support of the government and of the local government. In the case of a business operator, the priority in total importance was deduced to be in the order of natural environment, infrastructure, and man-made environment. Consequently, it is necessary to reflect customer needs during the establishment of the planning of a complex so that no differences in perception between suppliers and consumers appear.

MA법으로 제조된 CrSi₂ 열전화합물의 평가 및 치밀화

이충효,김영,Lee, Chung-Hyo,Kim, Young 한국결정성장학회 2013 한국결정성장학회지 Vol.23 No.3

본 연구에서는 $CrSi_2$ 열전화합물을 제조하기 위하여 순금속 $Cr_{33}Si_{67}$ 혼합분말을 기계적 합금화 처리하였다. 초미세 $CrSi_2$계 열전화합물을 얻기 위하여 최적 볼밀조건 및 열처리 조건을 X선 회절분석과 시차주사 열량분석을 이용하여 조사하였다. 순금속 $Cr_{33}Si_{67}$ 혼합분말을 70시간까지 볼밀 처리 후 $650^{\circ}C$까지 열처리함으로써 평균 결정립 크기가 70 nm 인 초미세 $CrSi_2$ 열전화합물을 얻을 수 있었다. MA 분말시료의 벌크화를 위하여 소결온도 $600{\sim}1000^{\circ}C$, 압력 60 MPa에서 SPS 소결을 실시하였다. SPS 과정에서 MA 분말의 수축은 소결 개시 후 $600^{\circ}C$ 전후에서 크나 전반적으로 급격하게 발생하지 않으며 $1000^{\circ}C$까지 비교적 단조롭게 수축함을 알 수 있었다. 여기서 수축이 $600^{\circ}C$ 부근에서 큰 이유는 열분석 결과에서도 보여주듯이 $CrSi_2$ 화합물의 생성과 관련이 있는 것으로 판단된다. SPS 성형체의 전기전도도 및 제벡계수는 $900^{\circ}C$까지 측정을 실시하였으며, 그 결과로부터 제벡계수는 $400^{\circ}C$에서 $125{\mu}V/K$ 및 파워팩터는 $350^{\circ}C$에서 $4.3{\times}10^{-4}W/mK^2$의 최대값을 각각 나타내었다. Mechanical alloying was carried out to produce $CrSi_2$ thermoelectric compound using a mixture of elemental $Cr_{33}Si_{67}$ powders. An optimal milling and heat treatment conditions to obtain the single phase of $CrSi_2$ compound with fine microstructure were investigated by X-ray diffraction and differential scanning calorimetry measurement. $CrSi_2$ intermetallic compound with a grain size of 70 nm could be obtained by MA of $Cr_{33}Si_{67}$ powders for 70 hours and subsequently annealed at $650^{\circ}C$. Consolidation of the MA powders was performed in a spark plasma sintering (SPS) machine using graphite dies at $600{\sim}1000^{\circ}C$ under 60 MPa. The shrinkage of MA samples during SPS consolidation process increased gradually with increasing temperature up to $1000^{\circ}C$ and relatively significant at about $600^{\circ}C$. We tend to believe that these behaviors are deeply related to form a $CrSi_2$ compound during heating process, as can be realized from the DSC measurement. Electrical conductivity and Seebeck coefficient of sintered bodies were measured up to $900^{\circ}C$. Seebeck coefficient and power factor of $Cr_{33}Si_{67}$ compact prepared by MA and SPS at $1000^{\circ}C$ showed the maximum value of $125{\mu}V/K$ at $400^{\circ}C$ and $4.3{\times}10^{-4}W/mK^2$ at $350^{\circ}C$, respectively.

기계적 합금화한 $\sigma$-VFe합금의 중성자 및 X선 회절에 의한 상분석

이충효,조재문,이상진,심해섭,이창희,Lee, Chung-Hyo,Jo, Jae-Mun,Lee, Sang-Jin,Sim, Hae-Seop,Lee, Chang-Hui 한국재료학회 2001 한국재료학회지 Vol.11 No.8

$\sigma$-VFe 금속간화합물에 대한 기계적 합금화(MA) 효과를 중성자 및 X선 회절법으로 조사하였다. MA 분말의 구조분석은 X선 회절(Cu-K$\alpha$) 린 중성자회절(HRPD, λ=1.835$\AA$)을 이용하여 행하였다. $\sigma$-VFe화합물의 MA시 큰 구조변화가 관찰되었으며, MA 60시간의 경우 Fe-Fe 훤자분포는 unit cell에 30개의 원자를 포함하고 있는 $\sigma$상의 tetragonal구조에서 $120^{\circ}C$이상에서 안정하게 존재하는 $\alpha$-(V,Fe) 고용체의 bcc 구조로 상변화함을 알 수 있었다. 또한 $\alpha$-VFe 화합물에 대한 중성자 및 X선 회절패턴의 비교분석을 행하였으며 그 결과 $\sigma$상이 가지는 화학적 규칙성에 기인하는 (101)과 (111) 회절 피크가 중성자 회절에서 뚜렷하게 관찰됨을 알 수 있었다. The mechanical alloying (MA) effect in $\sigma$-VFe intermetallic compound was studied by neutron and X-ray diffraction. The structure of MA $\sigma$-VFe powders were characterized by the X- ray diffraction with Cu- $K\alpha$ radiation and neutron diffraction with monochromatic neutrons of $1.835\AA$ using a high resolution powder diffractometer (HRPD). Mechanical alloying of $\sigma$-VFe compound gives rise to a dramatic structural change. After 60 hours of MA, the Fe-Fe distribution of the $\sigma$- phase VFe tetragonal structure with 30 atoms in a unit cell is found to change into that of the $\sigma$-(V,Fe) solid solution with bcc structure, which is a stable phase at elevated temperature above $1200^{\circ}C$. A comparison of X-ray diffraction data for the $\alpha$-phase has been also made with the corresponding neutron diffraction data. The (101) and (111) diffraction peaks of the $\sigma$-phase was clearly observed only in neutron diffraction pattern, which is believed to be a characteristic feature due to the chemical atomic ordering of $\sigma$- VFe phase.